Root hemiparasites suppress invasive alien clonal
plants: evidence from a cultivation experiment
Tamara Těšitelová1
, Kateřina Knotková1
,
Adam Knotek1
, Hana Cempírková2
, Jakub Těšitel1
1 Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech
Republic 2 Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37
Brno, Czech Republic
Corresponding author: Tamara Těšitelová (tamara.malinova@centrum.cz)
Academiceditor:R.Bustamante  |  Received22September2023  |  Accepted29November2023  |  Published15January2024
Citation: Těšitelová T, Knotková K, Knotek A, Cempírková H, Těšitel J (2024) Root hemiparasites suppress
invasive alien clonal plants: evidence from a cultivation experiment. NeoBiota 90: 97–121. https://doi.org/10.3897/
neobiota.90.113069
Abstract
Alien invasive plants threaten biodiversity by rapid spread and competitive exclusion of native plant species.
Especially, tall clonal invasives can rapidly attain strong dominance in vegetation. Root-hemiparasitic
plants are known to suppress the growth of clonal plants by the uptake of resources from their belowground
organs and reduce their abundance. However, root-hemiparasites’ ability to interact with alien
clonal plants has not yet been tested.
We explored the interactions between native root-hemiparasitic species, Melampyrum arvense and
Rhinanthus alectorolophus and invasive aliens, Solidago gigantea and Symphyotrichum lanceolatum. We investigated
the haustorial connections and conducted a pot experiment. We used seeds from wild hemiparasite
populations and those cultivated in monostands of the invasive plants to identify a possible selection
of lineages with increased compatibility with these alien hosts. The hemiparasitic species significantly
suppressed the growth of the invasive plants. Melampyrum inflicted the most substantial growth reduction
on Solidago (78%), followed by Rhinanthus (49%). Both hemiparasitic species reduced Symphyotrichum
biomass by one-third. Additionally, Melampyrum reduced the shoot density of both host species. We also
observed some transgenerational effects possibly facilitating the growth of hemiparasites sourced from
subpopulations experienced with the host.
Native root hemiparasites can effectively decrease alien clonal plants’ biomass production and shoot
density. The outcomes of these interactions are species-specific and may be associated with the level of
clonal integration of the hosts. The putative selection of lineages with higher performance when attached
to the invasive novel hosts may increase hemiparasites’ efficiency in future biocontrol applications.
NeoBiota 90: 97–121 (2024)
doi: 10.3897/neobiota.90.113069
https://neobiota.pensoft.net
Copyright TamaraTěšitelová et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC
BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
RESEARCH ARTICLE
Advancing research on alien species and biological invasions
A peer-reviewed open-access journal
NeoBiota
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)98
Keywords
Asteraceae, biological invasion, biotic resistance, Orobanchaceae, physiological integration, pot experiment,
restoration
Introduction
Alien plant invasions represent a component of global change with profound effects on
diversity, ecosystem functioning and services. Invasive species broadly vary in their specific
impacts on the habitats they invade due to different abilities to spread and achieve
dominance or mechanisms of interaction with native biota (Blackburn et al. 2014).
Of particular concern are the so-called transformer invaders (Richardson et al. 2000),
which can invade indigenous natural communities over large areas, attain high dominance
and change ecosystem functioning. Alien tall clonal herbs with below-ground
rhizomes are frequent examples of transformer invaders in grasslands due to their increased
competitiveness leading to the exclusion of native plants from infested vegetation
throughout temperate regions (Divíšek et al. 2018; Wang et al. 2019; Wan et al.
2021; Lanta et al. 2022). Although conventional control management, represented by
mowing or grazing, can reduce the density of the invasive clonal herbs to some extent
(e.g. Nagy et al. (2020); Szymura et al. (2022)), they are usually not eliminated and
may spread rapidly from the rhizomes if the management measures are ceased. More
drastic restoration measures (e.g. use of herbicides, long-term shading) may eradicate
the invaders, but can also adversely affect native species, making their use problematic
in areas with conservation value (e.g. Weber and Jakobs (2005); Szymura et al. (2022)).
Native parasitic plants have recently been suggested as potential biocontrol agents
for a wide range of invasive plants globally (Těšitel et al. 2020). Following the biotic
resistance hypothesis (Maron and Vilà 2001), generalist native adversaries, such as
parasitic plants, may impede the success of invaders due to the lack of defence or
tolerance mechanisms of the host plants against parasitism (Cameron and Seel 2007).
Clonal hosts could be especially harmed by parasitism, as the parasitic uptake of resources
targets the cornerstone of their growth strategy, that is, the spatial spread of
vegetative ramets and clonal integration (e.g. Song et al. (2013); Roiloa (2019)), i.e.
the transfer of resources amongst interconnected ramets via rhizome network, which
facilitates efficient resource acquisition and sharing (Kavanová and Gloser 2005; Gao
et al. 2021). However, parasitic plants may turn this advantage into a liability. A parasite
that attaches to one ramet may access nutrients within the network, leading to
its vigorous growth and potentially marked biomass decline of the clonal host, including
the non-infected ramets (Lepš and Těšitel 2015; Gao et al. 2021). This could
explain a substantial decrease in the clonal hosts’ abundance in the communities with
parasitic plants observed in several studies (Decleer et al. 2013; Demey et al. 2015;
Somodi et al. 2018). Moreover, field experiments have demonstrated the ability of
root-hemiparasitic Rhinanthus species to significantly reduce harmful expansive clonal
grass Calamagrostis epigejos from semi-natural grasslands (Těšitel et al. 2017, 2018),
Root hemiparasites suppress invasive clonal plants 99
which was consequently introduced to ecological restoration practice (Lukavský 2020;
SPPK D02 002 2021).
Amongst parasitic plants, species of root hemiparasites (or, more precisely, Euphytoid
parasites in the new parasitic plant classification of Teixeira-Costa and Davis
(2021)) appear to be particularly suitable candidates for suppressing clonal invasive
species due to their low host specificity (e.g. Matthies (2017, 2021)), capacity to substantially
suppress host growth (e.g. Press et al. (2005); Těšitel et al. (2015b); Matthies
(2021)) and ability to form dense populations (van Hulst et al. 1987; Mudrák
and Lepš 2010; Heer et al. 2018). Despite available evidence on the negative effects of
root hemiparasites on expansive species (reviewed by Těšitel et al. (2020)), only one
study has investigated the effect of a root-hemiparasitic species on an alien invader
(Walder et al. 2019), which, however, did not show any adverse impact of the parasite
on the host species. Two reasons may explain this lack of empirical research on interactions
between root hemiparasites and alien invaders. First, hemiparasites and alien
invaders may not share the same habitats. For instance, in Central Europe, an analysis
of habitats of hemiparasitic species identified natural and semi-natural communities
as their principal habitats (Těšitel et al. 2015a). These habitats are simultaneously
characterised by low levels of alien invasions (Pyšek et al. 2012). Second, establishing
a parasitic association with alien invaders may be difficult. Although hemiparasites
are mostly host generalists, host quality (i.e. the extent of support of parasite growth)
varies between species (e.g. Rowntree et al. (2014); Matthies (2017, 2021)). Native
hemiparasitic species lack a common evolutionary history with non-indigenous
plants. The lack of experience with an alien host may limit a hemiparasite’s efficiency
of resource withdrawal on the one hand, but also the host’s resistance or tolerance
to parasitism on the other, as predicted by the biotic resistance hypothesis. Compatibility
with a host may also be affected by high intra- and interpopulation genotypic
variability of the annual hemiparasites (Mutikainen et al. 2000; Rowntree et al. 2011;
Unachukwu et al. 2017; Rowntree and Craig 2019; Moncalvillo and Matthies 2023).
The recognised ability to rapidly evolve ecotypes adapted to various environmental
conditions (Zopfi 1993; Pleines et al. 2013) may further facilitate the interaction
with novel host species.
In this paper, we investigated the interactions between root-hemiparasitic Rhinanthus
alectorolophus and Melampyrum arvense (Orobanchaceae) and the alien invasive
clonal species Solidago gigantea and Symphyotrichum lanceolatum (Asteraceae). First, we
examined the anatomy of haustoria to determine whether the hemiparasites can form
functional parasitic connections with the novel hosts. Second, we set up a comprehensive
pot experiment to study the effect of host identity on hemiparasite performance
and the impact of hemiparasite infection on the two hosts. We expected to identify differences
in vitality (measured by biomass production) of the two hemiparasite species
(hypothesis 1), which should be reflected by a difference in host suppression (hypothesis
2). Specifically, we expected lower host suppression by Rhinanthus, given its general
preference for grass or legume hosts (Matthies 2021), than in Melampyrum, which has
been shown to flourish when attached to various forbs, including many Asteraceae
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)100
(Matthies 2017). Furthermore, we investigated the potential selection of hemiparasite
lineages and their effect on host–hemiparasite interactions. To do so, we used seeds
from hemiparasites that had grown for two years in monoculture stands of the two host
species and compared their performance to plants from the original population from a
species-rich grassland (‘naïve’ plants), i.e. all tested seed sources per hemiparasite species
originated from a single hemiparasite population. We hypothesised that growth in
a host monoculture might lead to a selection of lineages better adapted to the given
host, reflected by improved hemiparasite growth and possibly a more deleterious effect
on that host (hypothesis 3).
Materials and methods
Study species
Melampyrum arvense L. and Rhinanthus alectorolophus (Scop.) Pollich are annual xylemfeeding
root-hemiparasitic species native to Europe. Melampyrum typically grows in
dry grasslands and steppes, while Rhinanthus alectorolophus (Scop.) Pollich favours dry
to mesic grasslands. Solidago gigantea Aiton and Symphyotrichum lanceolatum (Willd.)
G. L. Nesom are perennial rhizomatous species from the Asteraceae family, originating
from North America (Pyšek et al. 2012). They began spreading across Europe in
the 19th
century and have become serious invaders (Weber and Jakobs 2005; Jedlička
and Prach 2006; Axmanová et al. 2021). Solidago and Symphyotrichum are considered
typical wetland species, but they also occur in disturbed anthropogenic habitats,
poorly-managed fields, pastures and meadows within their native range (Chmielewski
and Semple 2001; Weber and Jakobs 2005). Solidago has a broader ecological niche in
the invaded areas, also occupying drier and nutrient-poorer soils (Weber and Jakobs
2005). Both species have a perennial rhizome, which, in the spring, produces a cohort
of shoots that start to flower in late summer (Solidago) or early autumn (Symphyotrichum)
and yield numerous tiny wind-dispersed seeds. Jedlička and Prach (2006) noted
the high viability of Symphyotrichum lanceolatum seeds, which, combined with the
effective ability to penetrate established vegetation, triggers the high invasive potential
of this species.
Haustorial connection
We initiated a pilot cultivation trial to examine the anatomy of haustorial connections
between the hemiparasites and the two invasive hosts. The cultivation was set up in the
experimental garden of the Department of Botany and Zoology at Masaryk University
in Brno, Czech Republic. The hemiparasites’ seeds were collected from species-rich
vegetation in the summer of 2019 (see Suppl. material 1: appendix S1 for localisations).
In the autumn of 2019, we transplanted rhizomes of host species into 15 × 15 ×
20 cm pots (narrower at the bottom, corresponding to 3.6 litres), filled with a mixture
Root hemiparasites suppress invasive clonal plants 101
of peat and garden soil (ratio 1:3). In October, we sowed 20 hemiparasite seeds on each
pot. We established five replicates for each hemiparasite-host combination.
In June 2020, we rinsed the hosts’ roots, harvested the haustoria and preserved
them in 70% ethanol. Following the method of Soukup and Tylová (2014), we dehydrated
the samples, transferred them to anhydrous butanol, infiltrated and then
embedded them in paraffin. We prepared 12 µm sections using a sliding microtome
(Reichert, Wien, Austria) and de-waxed and stained them with phloroglucinol-HCl
(Wiesner solution) (Liljegren 2010) to colour the lignified cell walls.
Cultivation experiment
We established the main pot experiment in autumn 2021 to investigate and quantify
the outcome of the novel interactions for the hemiparasites and the extent of
host suppression. For each hemiparasitic species, we used three seed sources: (i) seeds
from a wild population growing in a species-rich grassland and (ii) seeds from plants
originally obtained from the same populations as in (i), but which had been growing
since 2019 in monostands of the two invasive host species. The aim was to investigate
the potential selection of genotypes more adapted to the specific hosts. More specifically,
the monostands were mown in the autumn of 2019, after which we sowed the
hemiparasites’ seeds. In 2020, the monostands with hemiparasites were mown in July
and October. We collected ripe hemiparasite seeds from all populations from June to
July 2021. The seeds were stored at room temperature before use. As both host species
produce a dense rhizome network in the topsoil layer, we collected soil blocks with rhizomes
from monostands of each host species to establish host cultivation in September
2021. First, we removed the above-ground biomass and then cut approx. 12 × 12 cm
rhizome blocks with a spade. The rhizomes were then inserted into the same pots and
soil substrate described in the chapter ‘Haustorial connection’. See Suppl. material 1:
appendix S1 for GPS coordinates of the sites of hemiparasites’ seed and host plants’
origin.
The experimental design comprised: (i) an uninfected control treatment (host species
without hemiparasite seed addition) and three types of ‘infected’ treatments (with
hemiparasite seeds addition), i.e. treatments (ii) ‘naïve’ (seeds of hemiparasites originating
from a wild population), (iii) ‘home’ (seeds from hemiparasites growing for two
years in a monostand of a host species and then sown with the same host species in the
pot) and (iv) ‘cross’ (seeds from hemiparasites growing for two years in a monostand
of one host species and then sown into the pot with the other host species) (see the
scheme of the origin of hemiparasites’ seeds in Fig. 1). Both hemiparasites were sown
with both invasive species, resulting in 14 treatments. Each treatment consisted of 10
replicates of the pots, totalling 140 pots. Each pot in the ‘infected’ treatments (treatments
ii–iv) received 40 seeds of one of the hemiparasitic species. Seeds were spread on
the surface and gently mixed with the topsoil layer. The pots were then placed in the
experimental garden in Brno, following a completely randomised design and irrigated.
During spring 2022, the pots were irrigated as necessary. In April 2022, seedlings of
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)102
Figure 1. Scheme of origin of the hemiparasites’ seeds used in the cultivation experiment. In October
2019, seeds of Melampyrum arvense and Rhinanthus alectorolophus from a single population per species,
originating from a species-rich grassland, were sown in monostands of the host species Solidago gigantea
and Symphyotrichum lanceolatum. By 2021, hemiparasite seeds collected from the host species’ monostands
and the original hemiparasite population were used in the cultivation experiment resulting in three
types of hemiparasite seed sources: ‘naïve’, ‘home’ and ‘cross’.
Root hemiparasites suppress invasive clonal plants 103
non-target species were removed from the pots. The pots were spaced 30 cm apart and
their position within the experimental matrix was changed three times before harvest
at the beginning of June 2022.
The experiment was harvested during hemiparasite flowering. We cut the aboveground
biomass and counted the number of host shoots and hemiparasitic plants that
survived in each pot. The hemiparasite and host biomass from each pot were dried
separately at 80 °C and weighed. Schmid et al. (1995) revealed a strong dependency
of sexual reproduction and clonal growth on plant size as well as a threshold size for
sexual reproduction in Symphyotrichum lanceolatum and Solidago canadensis, a species
closely related to Solidago gigantea. We thus expected the vegetative biomass to reflect
host fitness and reproductive potential sufficiently.
Statistical analyses
Initially, we conducted an exploratory analysis of patterns in counts of hemiparasite
individuals, host ramets and above-ground biomass production to identify pots that
were not representative due to insufficient host or hemiparasite recruitment. Only
pots with at least six host shoots and three hemiparasite individuals (in infected treatments)
were subsequently included in the analysis (n = 132 out of 140 pots). Scatterplots
of biomass vs. individual or shoot counts (Suppl. material 1: appendices S2,
S3) demonstrated low correlations, indicating compensatory growth in pots retained
for the analysis.
We used linear models to analyse the following parameters: hemiparasite aboveground
biomass, the number of individuals, mean biomass per individual and host
above-ground biomass, the number of shoots and mean biomass per shoot. All variables
were log-transformed before analysis to improve the normality of residuals and
homogeneity of variances. The analysis of each parameter, used as response variables,
was conducted at two levels: (i) the species-level model included hemiparasite, host
species and their interaction as predictors. Seed-source treatments were disregarded in
this analysis; (ii) seed-source analysis consisted of a series of linear models, one for each
host–hemiparasite combination, with seed-source treatment as a single predictor. In
this analysis, we set treatment contrasts with the ‘naïve’ treatment as the baseline level,
to which the two other treatments were compared. Only biomass data were tested in
the seed-source level analysis.
We first built a saturated model for each analysis with all candidate predictors and
interactions. Individual terms of the saturated models were tested by an F-test, the
results of which are reported in ANOVA tables as in a classical two-way ANOVA with
interactions. Non-significant (P > 0.05) terms were subsequently removed from the
models in the backward predictor selection procedure. Non-significant main effects
were retained if a predictor was involved in a significant interaction. The resulting
minimal adequate models were then used to extract regression coefficients and their
associated tests of significance. This approach was allowed by the nature of our data
coming from a manipulative experiment with a balanced design, which implies the or-
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)104
thogonality of the predictors. We acknowledge that the orthogonality was not perfect
because we removed a few pots with low establishment of hosts or parasites. Still, the
collinearity between the tested effects (host and parasite predictors) was minimal as
measured by the phi-coefficient (φ = 0.026; χ1
= 0.0084; P = 0.927), which justifies the
validity of the interaction-term testing and supports backward selection as a suitable
model-selection approach. All analyses were performed in R, version 4.2.2 (R Core
Team 2022).
Results
Functional haustorial connection
Both hemiparasitic species formed fully developed haustoria on the roots and rhizomes
of both host species. In all cases, the xylem bridge from hemiparasite haustoria reached
the xylem vessels of the hosts. No signs of a defensive reaction by the hosts were observed
(Fig. 2).
Host–Hemiparasite interaction on the species level
Hosts successfully resprouted from rhizomes in the transferred soil blocks;
only four pots had to be omitted because of insufficient sprouting (Fig. 3,
Suppl. material 1: appendix S4). The number of hemiparasite plants varied in the pots,
but their establishment was generally successful, with only four pots omitted from the
experiment due to poor hemiparasite establishment. On average, 10.9 Melampyrum
plants were harvested in pots with both host species (max. 20 individuals). In contrast,
significantly higher average numbers of Rhinanthus plants, 16.2 and 13.2, were
harvested in pots with Solidago and Symphyotrichum (max. 23 individuals), respectively
(Table 1, Fig. 4, Suppl. material 2 for the primary data). Hemiparasite biomass
production differed between the two species and was also significantly affected by the
host identity (Table 1). Specifically, Melampyrum grew larger than Rhinanthus (t110
=
11.25, P < 10-6
) and Solidago supported a more vigorous hemiparasite growth than
Symphyotrichum (t110
= 10.12, P < 10-6
). These effects were additive, i.e. the difference
in the host quality had a similar impact on both hemiparasitic species (Fig. 4). Similar
trends and significant interactions were also found concerning the average biomass of
hemiparasite individuals (Table 1). Melampyrum individuals were consistently larger
than Rhinanthus and both hemiparasitic species produced larger specimens on Solidago
than on Symphyotrichum. However, this trend was less pronounced in Rhinanthus, i.e.
Rhinanthus individuals growing with Symphyotrichum were larger than expected by additive
effects (t109
= 2.57, P = 0.012; Fig. 4).
Regarding host suppression, we identified strong interactive effects of host and
hemiparasite species identities on the host biomass (Table 1). The hemiparasitic spe-
Root hemiparasites suppress invasive clonal plants 105
Figure 2. Cross sections of haustorial connections between two root-hemiparasitic species and their hosts.
In the hemiparasite haustoria (ha), there is a hyaline body (hb), the vascular core of the haustorium (vc)
and a xylem bridge (xb) leading to host xylem vessels (xv) in the host root (hr); xx – xylem–xylem contact.
cies significantly reduced host biomass relative to uninfected controls (Melampyrum:
t126
= -10.1, P < 10-6
, Rhinanthus: t126
= -4.53, P < 10-4
), but the suppression was
significantly more pronounced in Solidago infected by Melampyrum (t126
= 4.50, P <
10-5
; Fig. 5). Overall, Solidago biomass was reduced by 77.6% and 49.1% on average
when infected by Melampyrum and Rhinanthus, respectively. Symphyotrichum biomass
was reduced by 31.6% and 35.2% on average by Melampyrum and Rhinanthus,
respectively. Host biomass was reduced by decreasing the number of host shoots or
reducing the average biomass of host shoots. While Melampyrum acted in both ways,
Rhinanthus mainly decreased the average host shoot biomass (Fig. 5). In detail, Melampyrum
reduced the number of host shoots per pot (t128
= -4.05, P < 10-4
) by 33%
in Solidago and 21% in Symphyotrichum. The effect of Rhinanthus on the host shoot
number was not significant (t128
= -0.76, P = 0.45). Both Melampyrum (t126
= -7.07,
P < 10-6
) and Rhinanthus (t126
= -4.00, P < 0.001) reduced the average biomass of
host shoots. While Rhinanthus reduced the average shoot biomass of both hosts to a
similar extent, Melampyrum was significantly less deleterious to Symphyotrichum than
to Solidago (t126
= 3.98, P < 0.001).
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)106
Figure 3. Representative pots for each hemiparasite seed-source treatment (‘cross’, ‘home’, ‘naïve’) and
the uninfected control. Solidago gigantea (left) and Symphyotrichum lanceolatum (right) are infected by
Melampyrum arvense (top) or Rhinanthus alectorolophus (bottom). The bottom photo is flipped vertically
for clarity of the experiment presentation. Photographic documentation of all experimental pots is provided
in Suppl. material 1: appendix S4. Scale bars: 50 cm.
Effect of the hemiparasite seed origin on the interaction
We identified the significant effects of the hemiparasite seed-source treatments on
some interactions. Total hemiparasite biomass was affected in the case of Melampyrum
growing on Solidago (R2
= 0.29, F2,24
= 4.98, P = 0.016) and Rhinanthus growing on
Symphyotrichum (R2
= 0.32, F2,25
= 5.81, P = 0.008). Specifically, Melampyrum plants
Root hemiparasites suppress invasive clonal plants 107
Table 1. Analysis of variance tables summarising the effects of hemiparasite and host species identity on
the growth of hemiparasites and hosts.
Response Effect df Sum Sq. F P
Hemiparasite biomass Hemiparasite 1 13.72 121.95 < 10-6
Host 1 11.65 103.48 < 10-6
Hemiparasite × Host 1 0.24 2.10 0.15
Residuals 109 12.28
Hemiparasite count per pot Hemiparasite 1 3.89 19.64 < 10-4
Host 1 0.35 1.75 0.19
Hemiparasite × Host 1 0.29 1.46 0.23
Residuals 109 21.60
Hemiparasite average
biomass
Hemiparasite 1 32.23 203.10 < 10-6
Host 1 7.97 50.22 < 10-6
Hemiparasite × Host 1 1.05 6.61 0.011
Residuals 109 17.30
Host biomass Hemiparasite*
2 16.11 46.12 < 10-6
Host 1 0.02 0.13 0.72
Hemiparasite × Host 2 7.69 22.00 < 10-6
Residuals 126 22.00
Host shoot count per pot Hemiparasite*
2 2.53 13.09 < 10-5
Host 1 5.07 52.42 < 10-6
Hemiparasite × Host 2 0.31 1.59 0.21
Residuals 126 12.18
Host shoot average biomass Hemiparasite*
2 7.28 18.35 < 10-6
Host 1 5.77 29.10 < 10-6
Hemiparasite × Host 2 5.04 12.71 < 10-5
Residuals 126 24.99
*
The hemiparasite effect on host biomass also comprises non-infected control as an extra level.
in the ‘cross’ treatment (seeds from plants previously grown with the alternative invasive
host) produced significantly less biomass (t24
= -2.80, P = 0.010) compared to the
‘naïve’ treatment (seeds from species-rich vegetation), while the biomass of Melampyrum
on Solidago from the ‘home’ (seeds from plants previously grown with the same
host species) and ‘naïve’ treatment did not significantly differ (Fig. 6). Conversely, the
biomass of Rhinanthus on Symphyotrichum was significantly higher in the ‘home’ treatment
compared to the ‘naïve’ treatment (t25
= 3.09, P = 0.005) and the hemiparasite
biomass in the ‘cross’ and ‘naïve’ treatment did not differ (Fig. 6).
Host biomass was significantly affected only in the case of Solidago infected by
Rhinanthus (R2
= 0.27, F2,27
= 5.09, P = 0.013) (Fig. 7). Here, Rhinanthus of ‘home’
and ‘cross’ treatments suppressed Solidago biomass more than ‘naïve’ Rhinanthus
plants (t27
= -2.73, P = 0.011 and t27
= -2.80, P = 0.009 for ‘home’ and ‘cross’ treatments,
respectively).
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)108
Figure 4. Effects of host species on the total biomass, number of individuals per pot and average biomass
of the individuals of the two hemiparasitic species. Boxplots represent median, quartiles and ranges. See
Table 1 for the ANOVA tables summarising significance tests. Note the logarithmic scale of the y-axes.
Root hemiparasites suppress invasive clonal plants 109
Figure 5. Effect of hemiparasite infection on total biomass, number of shoots per pot and average shoot
biomass of the two host species. Boxplots represent median, quartiles and non-outlier ranges, with outliers
displayed as points outside the non-outlier ranges. Note the logarithmic scale of the y-axes. See Table 1 for
the ANOVA tables summarising significance tests.
Discussion
The outcome of the novel host–hemiparasite interactions
Both root-hemiparasitic species established a functional parasitic association with the
two novel host species, as evidenced by functional haustorial connection, vital growth
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)110
and flowering of both parasites (Figs 2, 3). In line with our first hypothesis, the hemiparasite
species differed in compatibility with the two invasive hosts from Asteraceae,
with Melampyrum proving a more efficient parasite than Rhinanthus. This outcome is
not surprising, as Melampyrum has previously been shown to thrive when attached to
a series of forbs. Asteraceae species, such as Achillea millefolium, Matricaria chamomilla
and Taraxacum officinale, were even amongst the top five hosts out of 27 potential hosts
tested (Matthies 2017). The average biomass of Melampyrum individuals of ca. 500 mg
on Solidago and 300 mg on Symphyotrichum classifies these species amongst the best or
moderately good hosts, respectively (in comparison to Matthies (2017)). Rhinanthus
spp. have been repeatedly reported to grow better when attached to grasses or legumes
Figure 6. Effect of seed-source treatments on hemiparasite biomass production categorised by the individual
host–hemiparasite combinations. Boxplots represent median, quartiles and non-outlier ranges,
with outliers displayed as points outside the non-outlier ranges. P-values indicate significant effects of
seed-source treatments. Note the logarithmic scale of the y-axes.
Root hemiparasites suppress invasive clonal plants 111
than forbs (Cameron and Seel 2007; Rowntree et al. 2014; Matthies 2021). The biomass
production of Rhinanthus alectorolophus, converted to values per 1 m2
, amounted
to 136 g DW and 75.6 g DW when attached to Solidago and Symphyotrichum, respectively.
These values are lower than those reported for the best grass hosts in a recent field
cultivation experiment (Hejduk et al. 2020). Still, Solidago can be considered a similarly
good host for Rhinanthus alectorolophus as Lotus corniculatus, the best host amongst
legumes. Symphyotrichum is a host of lower quality, but still comparable to some grasses
(Festuca rubra) or legumes (Trifolium hybridum) (Hejduk et al. 2020). Compared to
pot cultivations, the two invasive hosts can also be considered of at least moderate qualFigure
7. Effect of seed-source treatments on host biomass production in infected pots categorised by the
individual host–hemiparasite combinations. Boxplots represent median, quartiles and non-outlier ranges,
with outliers displayed as points outside the non-outlier ranges. P-values indicate significant effects of
seed-source treatments. Note the logarithmic scale of the y-axes.
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)112
ity for Rhinanthus alectorolophus with an average biomass of individuals of about 220
mg and 150 mg on Solidago and Symphyotrichum, respectively. The biomass values per
individual may be up to five times higher with the best host species in greenhouse pot
cultivations (Těšitel et al. 2015b; Matthies 2021). However, the hemiparasitic plants
in these cultivation experiments could benefit from optimal greenhouse conditions,
including sufficient soil nutrients and reduced intraspecific competition due to the
presence of only a single hemiparasite individual in each pot (Matthies 2021).
Both hemiparasitic species significantly suppressed the growth of both host species,
which is the first experimental demonstration of an adverse effect of root hemiparasites
on invasive species. We expected that the growth of the hemiparasites would correlate
with the level of host suppression (hypothesis 2), which was only partially supported.
Both hemiparasitic species reduced Symphyotrichum above-ground biomass by a third
despite a significant difference in hemiparasite biomass (Figs 4, 5). Conversely, Solidago
growth was reduced by 80% and 50% when parasitised by Melampyrum and Rhinanthus,
respectively, corresponding to the difference in biomass production of the two
hemiparasitic species and also to maximal levels of host biomass suppression reported
from previous pot experiments (70% and 65% by Melampyrum arvense and Rhinanthus
alectorolophus, respectively; Těšitel et al. (2015b); Matthies (2017); Sandner and
Matthies (2018)). The difference in the host suppression could be related to their
clonal growth characteristics, specifically the persistence of ramet connection. The
clonal connections of Solidago ramets may persist for several years, while connections
amongst Symphyotrichum ramets decay after one year (Schmid et al. 1995; Klimešová
and Klimeš 2006). Schmid and Bazzaz (1987) suggested stronger physiological integration
in Solidago due to the larger effects of experimental rhizome severance on Solidago
gigantea growth than Symphyotrichum. The persistent clonal spread was identified
as a significant positive predictor of hemiparasite-induced growth reduction (Demey
et al. 2015); thus, the putatively stronger integration of Solidago ramets could be one
of the reasons for the more extensive damage inflicted by the parasites. Physiological
integration may be a trait contributing to a species’ susceptibility to plant parasitism.
Examining the interactions between clonal hosts and hemiparasites presents a challenging
task. Pot experiments are necessary to isolate the interaction between the host
and the generalist hemiparasites from the natural community context, ensuring no
other plant serves as a host. Typically, hosts are grown from seeds in these experiments,
with hemiparasites later germinating in the pots or being transplanted as pregerminated
seedlings. Consequently, hemiparasites attach to young host individuals
that have not yet developed clonal growth. Furthermore, arbitrary numbers of host
and hemiparasite individuals (sometimes as low as one host with one hemiparasite)
are used in most of the pot experiments (e.g. Cameron and Seel (2007); Rowntree et
al. (2014); Těšitel et al. (2015b); Matthies (2017); Sandner and Matthies (2018); but
see, for example, Matthies (1995) and Hejduk et al. (2020) for hemiparasite densitymanipulation
experiments). These issues limit the potential of such experiments to
elucidate the clonal host–hemiparasite interaction because, in natural communities,
hemiparasite seedlings mostly attach to mature individuals of perennial plants with a
Root hemiparasites suppress invasive clonal plants 113
fully-developed root system and clonal-growth organs. Thanks to transplanting whole
soil blocks from the host population, our experiment maintains the host plant properties
(developmental stage, ramet density) as close to natural conditions as possible. In
addition, the hemiparasite seedlings were permitted to develop under natural climatic
conditions, host phenological development and at densities close to realistic values
(van Hulst et al. 1987; Mudrák and Lepš 2010). Hence, our experiment paves the
way to more realistic pot experiments studying clonal host–hemiparasite interactions,
which are of particular significance in European grassland ecosystem (Demey et al.
2015; Lepš and Těšitel 2015; Těšitel et al. 2017).
Conservation perspective
Pronounced biomass suppression of Solidago and Symphyotrichum is noteworthy from
the restoration perspective. Both species are invasive, often achieving dominance and
significantly impacting above-ground diversity (Hejda et al. 2021; Cubino et al. 2022;
Fenesi et al. 2023). Solidago spp. also affected below-ground soil properties and the activity
and biomass of soil bacteria and fungi (Zhang et al. 2009a, b; Scharfy et al. 2010;
Pergl et al. 2023). Both species are listed in the second most serious category in the
Black List of invasive species (BL2) with a massive environmental impact (Pergl et al.
2016). Hence, reducing their populations is crucial, particularly at sites of high conservation
values. Mowing twice, a standard management technique for vegetation infested
with Solidago gigantea, reduces the species’ dominance. Cover reduction by 75% of the
initial cover was reported over the long term, but the species is still persistent in the
vegetation (Nagy et al. 2020; Szymura et al. 2022). A more pronounced suppression of
Solidago may be achieved through cattle and sheep grazing or flooding (> 95% suppression;
Nagy et al. (2020)). Despite the rapid spread of Symphyotrichum lanceolatum in
wetland habitats of high natural value (Lanta et al. 2022), no information on managing
this invasion is available. Biological control by introducing specialised insects or fungi
from the species’ native range has not been established yet in the invaded ranges, though
several non-native insect enemies may be available in the case of Solidago (Fontes et al.
1994; Sheppard et al. 2006). Another biocontrol option available in subtropical regions
may represent the widely-spread fungus Sclerotium rolfsii, causing the southern blight
disease. Wilting of Solidago canadensis, induced by this fungus, has been reported from
China (Tang et al. 2010) and the fungus application combined with soil disturbance
led to 90% decrease in Solidago canadensis stem density (Zhang et al. 2019).
Using native hemiparasitic plants in combination with standard mowing management
may offer another tool for the biocontrol of the two study species without
any potential risks of introducing alien organisms to the ecosystems. The effects of
hemiparasites on the invasive hosts observed in our experiment are comparable to the
level of the suppression of Calamagrostis epigejos by Rhinanthus alectorolophus reported
in previous research (Těšitel et al. 2017). The reduction and even elimination of this
expansive grass by Rhinanthus have been established as a standard tool of biodiversity
restoration in nature conservation in the Czech Republic (SPPK D02 002 2021). In
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)114
contrast, Melampyrum arvense has not been used in ecological restoration so far, possibly
because it is now considered a vulnerable species confined mainly to steppes and
protected areas in Central Europe (Těšitel et al. 2015a). However, this species used to
be a noxious weed in winter cereal fields (e.g. Rau (1970); Çetinsoy (1980); Matthies
(1995)). It can increase its biomass by 1/3 in nutrient-rich soil and prefers hosts from
nutrient-rich environments (Matthies 2017). Such ecological characteristics align with
the ecology of Solidago and Symphyotrichum, sometimes called ‘old-field perennials’
(Schmid and Bazzaz 1987; Schmid et al. 1995), which efficiently colonise bare ground,
fallows and disturbed urban areas and thrive in humid, nutrient-rich soils. Our experimental
results demonstrate the ability of both hemiparasites to suppress the invasive
species, but implementing this finding in ecological restoration requires further testing
in the field conditions over longer periods.
Genotype adaptation
We identified transgenerational effects in hemiparasitic interactions thanks to using
hemiparasite seeds of the same population origin, but cultivated for two generations
(= years) with the target host. The effects were not universal across all host–hemiparasite
combinations; however, where present, they generally supported our hypothesis 3.
Specifically, when the hemiparasites were exposed to the target host species during two
previous generations, the offspring plants produced relatively more biomass (Fig. 6) or
were more detrimental to the host (Fig. 7) in some host–hemiparasite combinations.
The effects were more pronounced on the hemiparasite side of the association, a pattern
identified in a previous study on genotype effects in root-hemiparasitic interactions
(Rowntree et al. 2014). Two mechanisms may be at play here: classical genetics and the
selection of alleles that provide better compatibility with a host species or epigenetic
(maternal) effects acting in the same way (Anastasiadi et al. 2021). We are not able to
distinguish between these two with the current data. Even in model organism studies,
the state-of-the-art methodology struggles to provide absolute separation of selection
and epigenetics (Schmid et al. 2018). However, any adaptive process facilitating the
association with novel hosts is crucial for the biotic resistance role of the parasites.
The existence of transgenerational effects in host–hemiparasite compatibility suggests
that the breeding of genotypes more compatible with the target invasive hosts
or exposing the mother plants to the novel host species may potentially increase the
success of biocontrol applications, at least in the case of Rhinanthus. The feasibility of
such an approach is also supported by the observations of rapid adaptive evolution
in Rhinanthus alectorolophus in response to environmental conditions and host species
(Zopfi 1993; Pleines et al. 2013; Moncalvillo and Matthies 2023). The genetic
diversity of hemiparasites was also demonstrated to be a significant predictor of their
establishment success and fitness when cultivated with multiple host species (Rowntree
and Craig 2019). Therefore, while breeding hemiparasites in monospecific host stands
may be efficient for specific purposes, it is equally important to preserve the genetic
diversity of the populations of hemiparasitic species in nature and in seed production
Root hemiparasites suppress invasive clonal plants 115
for ecological restoration; for instance, by cultivating hemiparasites with various host
species from different plant functional groups so that the pool of genotypes efficient in
various host–hemiparasites combinations is not depleted.
Acknowledgements
The authors thank Pavel Dřevojan, Zuzana Plesková, Zdenka Preislerová, Terezie
Chamrátová, Maroš Šlachtič for help with the experiment setting and harvesting and
David Watson and Ramiro Bustamante for their insightful comments on the manuscript.
This work was supported by the Czech Science Foundation (project 21-22488S).
References
Anastasiadi D, Venney CJ, Bernatchez L, Wellenreuther M (2021) Epigenetic inheritance and
reproductive mode in plants and animals. Trends in Ecology & Evolution 36(12): 1124–
1140. https://doi.org/10.1016/j.tree.2021.08.006
Axmanová I, Kalusová V, Danihelka J, Dengler J, Pergl J, Pyšek P, Večeřa M, Attorre F, Biurrun
I, Boch S, Conradi T, Gavilán RG, Jiménez-Alfaro B, Knollová I, Kuzemko A, Lenoir
J, Leostrin A, Medvecká J, Moeslund JE, Obratov-Petkovic D, Svenning J-C, Tsiripidis I,
Vassilev K, Chytrý M (2021) Neophyte invasions in European grasslands. Journal of Vegetation
Science 32(2): e12994. https://doi.org/10.1111/jvs.12994
Blackburn TM, Essl F, Evans T, Hulme PE, Jeschke JM, Kühn I, Kumschick S, Marková Z,
Mrugała A, Nentwig W, Pergl J, Pyšek P, Rabitsch W, Ricciardi A, Richardson DM, Sendek
A, Vilà M, Wilson JRU, Winter M, Genovesi P, Bacher S (2014) A unified classification of
alien species based on the magnitude of their environmental impacts. PLoS Biology 12(5):
e1001850. https://doi.org/10.1371/journal.pbio.1001850
Cameron DD, Seel WE (2007) Functional anatomy of haustoria formed by Rhinanthus minor:
Linking evidence from histology and isotope tracing. The New Phytologist 174(2): 412–
419. https://doi.org/10.1111/j.1469-8137.2007.02013.x
Çetinsoy S (1980) Studies on the Determination of Effective Chemicals Against Melampyrum
arvense L., Harmful in Cereals Fields in Central Anatolia. Bölge Zirai Mücadele Arastima
Enstitüsu, Ankara.
Chmielewski JG, Semple JC (2001) The biology of Canadian weeds. 113. Symphyotrichum
lanceolatum (Willd.) Nesom [Aster lanceolatus Willd.] and S. lateriflorum (L.) Löve & Löve.
Canadian Journal of Plant Science 81(4): 829–849. https://doi.org/10.4141/P00-056
[Aster lateriflorus (L.) Britt.]
Cubino JP, Těšitel J, Fibich P, Lepš J, Chytrý M (2022) Alien plants tend to occur in speciespoor
communities. NeoBiota 73: 39–56. https://doi.org/10.3897/neobiota.73.79696
Decleer K, Bonte D, Van Diggelen R (2013) The hemiparasite Pedicularis palustris: ‘Ecosystem
engineer’ for fen-meadow restoration. Journal for Nature Conservation 21(2): 65–71.
https://doi.org/10.1016/j.jnc.2012.10.004
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)116
Demey A, De Frenne P, Baeten L, Verstraeten G, Hermy M, Boeckx P, Verheyen K (2015)
The effects of hemiparasitic plant removal on community structure and seedling establishment
in semi-natural grasslands. Journal of Vegetation Science 26(3): 409–420. https://
doi.org/10.1111/jvs.12262
Divíšek J, Chytrý M, Beckage B, Gotelli NJ, Lososová Z, Pyšek P, Richardson DM, Molofsky
J (2018) Similarity of introduced plant species to native ones facilitates naturalization, but
differences enhance invasion success. Nature Communications 9(1): e4631. https://doi.
org/10.1038/s41467-018-06995-4
Fenesi A, Botta‐Dukát Z, Miholcsa Z, Szigeti V, Molnár C, Sándor D, Szabó A, Kuhn T,
Kovács‐Hostyánszki A (2023) No consistencies in abundance–impact relationships across
herbaceous invasive species and ecological impact metrics. Journal of Ecology 111(5):
1120–1138. https://doi.org/10.1111/1365-2745.14085
Fontes EMG, Habeck DH, Slansky F (1994) Phytophagous insects associated with goldenrods
(Solidago spp.) in Gainesville, Florida. The Florida Entomologist 77(2): 209–209. https://
doi.org/10.2307/3495506
Gao F-L, Alpert P, Yu F (2021) Parasitism induces negative effects of physiological integration
in a clonal plant. The New Phytologist 229(1): 585–592. https://doi.org/10.1111/
nph.16884
Heer N, Klimmek F, Zwahlen C, Fischer M, Hölzel N, Klaus VH, Kleinebecker T, Prati D,
Boch S (2018) Hemiparasite-density effects on grassland plant diversity, composition and
biomass. Perspectives in Plant Ecology, Evolution and Systematics 32: 22–29. https://doi.
org/10.1016/j.ppees.2018.01.004
Hejda M, Sádlo J, Kutlvašr J, Petřík P, Vítková M, Vojík M, Pyšek P, Pergl J (2021) Impact
of invasive and native dominants on species richness and diversity of plant communities.
Preslia 93(3): 181–201. https://doi.org/10.23855/preslia.2021.181
Hejduk S, Bitomský M, Pornaro C, Macolino S (2020) Establishment of a hemiparasite Rhinanthus
alectorolophus and its density-dependent suppressing effect on a grass: A case
study from golf roughs. Agronomy Journal 112(5): 3619–3628. https://doi.org/10.1002/
agj2.20300
Jedlička J, Prach K (2006) A comparison of two North-American asters invading in central
Europe. Flora 201: 652–657. https://doi.org/10.1016/j.flora.2006.01.002
Kavanová M, Gloser V (2005) The use of internal nitrogen stores in the rhizomatous grass
Calamagrostis epigejos during regrowth after defoliation. Annals of Botany 95: 457–463.
https://doi.org/10.1093/aob/mci054
Klimešová J, Klimeš L (2006) Clo-Pla3–database of clonal growth of plants from Central Europe.
https://clopla.butbn.cas.cz
Lanta V, Liancourt P, Altman J, Černý T, Dvorský M, Fibich P, Götzenberger L, Hornych O,
Miklín J, Petřík P, Pyšek P, Čížek L, Doležal J (2022) Determinants of invasion by single
versus multiple plant species in temperate lowland forests. Biological Invasions 24(8):
2513–2528. https://doi.org/10.1007/s10530-022-02793-8
Lepš J, Těšitel J (2015) Root hemiparasites in productive communities should attack competitive
host, and harm them to make regeneration gaps. Journal of Vegetation Science 26(3):
407–408. https://doi.org/10.1111/jvs.12284
Root hemiparasites suppress invasive clonal plants 117
Liljegren S (2010) Phloroglucinol stain for lignin. Cold Spring Harbor Protocols 2010.1: pdb.
prot4954. https://doi.org/10.1101/pdb.prot4954
Lukavský J (2020) Funguje nám kokrhel? Aneb zkušenosti z regionu. Ochrana přírody 2020: 11–
15. https://www.casopis.ochranaprirody.cz/pece-o-prirodu-a-krajinu/funguje-nam-kokrhel/
Maron JL, Vilà M (2001) When do herbivores affect plant invasion? Evidence for the natural
enemies and biotic resistance hypotheses. Oikos 95(3): 361–373. https://doi.org/10.1034/
j.1600-0706.2001.950301.x
Matthies D (1995) Host-parasite relations in the root hemiparasite Melampyrum arvense. Flora
190(4): 383–394. https://doi.org/10.1016/S0367-2530(17)30680-1
Matthies D (2017) Interactions between a root hemiparasite and 27 different hosts: Growth,
biomass allocation and plant architecture. Perspectives in Plant Ecology, Evolution and
Systematics 24: 118–137. https://doi.org/10.1016/j.ppees.2016.12.006
Matthies D (2021) Closely related parasitic plants have similar host requirements and related
effects on hosts. Ecology and Evolution 11(17): 12011–12024. https://doi.org/10.1002/
ece3.7967
Moncalvillo B, Matthies D (2023) Performance of a parasitic plant and its effects on hosts depends
on the interactions between parasite seed family and host species. AoB Plants 15(2):
1–11. https://doi.org/10.1093/aobpla/plac063
Mudrák O, Lepš J (2010) Interactions of the hemiparasitic species Rhinanthus minor with its
host plant community at two nutrient levels. Folia Geobotanica 45(4): 407–424. https://
doi.org/10.1007/s12224-010-9078-1
Mutikainen P, Salonen V, Pustinen S, Koskela T (2000) Local adaptation, resistance, and virulence
in a hemiparasitic plant-host plant interaction. Evolution; International Journal of
Organic Evolution 54(2): 433–440. https://doi.org/10.1111/j.0014-3820.2000.tb00046.x
Nagy DU, Rauschert ESJ, Henn T, Cianfaglione K, Stranczinger S, Pal RW (2020) The more
we do, the less we gain? Balancing effort and efficacy in managing the Solidago gigantea
invasion. Weed Research 60(3): 232–240. https://doi.org/10.1111/wre.12417
Pergl J, Sádlo J, Petrusek A, Laštuvka Z, Musil J, Perglová I, Šanda R, Šefrová H, Šíma J,
Vohralík V, Pyšek P (2016) Black, Grey and Watch Lists of alien species in the Czech
Republic based on environmental impacts and management strategy. NeoBiota 28: 1–37.
https://doi.org/10.3897/neobiota.28.4824
Pergl J, Vítková M, Hejda M, Kutlvašr J, Petřík P, Sádlo J, Vojík M, Dvořáčková Š, Fleischhans
R, Lučanová A, Pyšek P (2023) Plant-soil interactions in the communities dominated
by alien and native plants. Perspectives in Plant Ecology, Evolution and Systematics 59:
e125721. https://doi.org/10.1016/j.ppees.2023.125721
Pleines T, Esfeld K, Blattner FR, Thiv M (2013) Ecotypes and genetic structure of Rhinanthus
alectorolophus (Orobanchaceae) in southwestern Germany. Plant Systematics and Evolution
299(8): 1523–1535. https://doi.org/10.1007/s00606-013-0816-8
PressMC,PressMC,PhoenixGK(2005)Impactsofparasiticplantsonnaturalcommunities.The
New Phytologist 166(3): 737–751. https://doi.org/10.1111/j.1469-8137.2005.01358.x
Pyšek P, Chytrý M, Pergl J, Sádlo J, Wild J (2012) Plant invasions in the Czech Republic:
Current state, introduction dynamics, invasive species and invaded habitats. Preslia 84:
575–629. https://www.preslia.cz/article/157
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)118
R Core Team (2022) R: A language and environment for statistical computing. R Foundation
for Statistical Computing, Vienna. http://www.R-project.org
Rau E (1970) Changes in the species spectrum of the noxious plant flora. Gesunde Pflanzen
22: 164–165.
Richardson DM, Pyšek P, Rejmánek M, Barbour MG, Dane Panetta F, West CJ (2000) Naturalization
and invasion of alien plants: Concepts and definitions. Diversity & Distributions
6(2): 93–107. https://doi.org/10.1046/j.1472-4642.2000.00083.x
Roiloa SR (2019) Clonal traits and plant invasiveness: The case of Carpobrotus N. E. Br.
(Aizoaceae). Perspectives in Plant Ecology, Evolution and Systematics 40: e125479. https://
doi.org/10.1016/j.ppees.2019.125479
Rowntree JK, Craig H (2019) The contrasting roles of host species diversity and parasite population
genetic diversity in the infection dynamics of a keystone parasitic plant. Journal of
Ecology 107(1): 23–33. https://doi.org/10.1111/1365-2745.13050
Rowntree JK, Cameron DD, Preziosi RF (2011) Genetic variation changes the interactions
between the parasitic plant-ecosystem engineer Rhinanthus and its hosts. Philosophical
Transactions of the Royal Society of London, Series B, Biological Sciences 366(1569):
1380–1388. https://doi.org/10.1098/rstb.2010.0320
Rowntree JK, Fisher Barham D, Stewart AJA, Hartley SE (2014) The effect of multiple host
species on a keystone parasitic plant and its aphid herbivores. Functional Ecology 28(4):
829–836. https://doi.org/10.1111/1365-2435.12281
Sandner TM, Matthies D (2018) Multiple choice: Hemiparasite performance in multi-species
mixtures. Oikos 127(9): 1291–1303. https://doi.org/10.1111/oik.05148
Scharfy D, Güsewell S, Gessner MO, Venterink HO (2010) Invasion of Solidago gigantea in
contrasting experimental plant communities: Effects on soil microbes, nutrients and plant
– soil feedbacks. Journal of Ecology 98(6): 1379–1388. https://doi.org/10.1111/j.1365-
2745.2010.01722.x
Schmid B, Bazzaz FA (1987) Clonal integration and population structure in perennials:
Effects of severing rhizome connections. Ecology 68(6): 2016–2022. https://doi.
org/10.2307/1939892
Schmid B, Bazzaz FA, Weiner J (1995) Size dependency of sexual reproduction and of clonal
growth in two perennial plants. Canadian Journal of Botany 73(11): 1831–1837. https://
doi.org/10.1139/b95-194
Schmid MW, Heichinger C, Schmid DC, Guthörl D, Gagliardini V, Bruggmann R, Aluri S,
Aquino C, Schmid B, Turnbull LA, Grossniklaus U (2018) Contribution of epigenetic
variation to adaptation in Arabidopsis. Nature Communications 9(1): e4446. https://doi.
org/10.1038/s41467-018-06932-5
Sheppard AW, Shaw RH, Sforza R (2006) Top 20 environmental weeds for classical biological
control in Europe: A review of opportunities, regulations and other barriers to adoption.
Weed Research 46(2): 93–117. https://doi.org/10.1111/j.1365-3180.2006.00497.x
Somodi I, Vadkerti Á, Těšitel J (2018) Thesium linophyllon parasitizes and suppresses expansive
Calamagrostis epigejos. Plant Biology 20(4): 759–764. https://doi.org/10.1111/plb.12723
Song Y, Yu F, Keser LH, Dawson W, Fischer M, Dong M, van Kleunen M (2013) United we
stand, divided we fall: A meta-analysis of experiments on clonal integration and its re-
Root hemiparasites suppress invasive clonal plants 119
lationship to invasiveness. Oecologia 171(2): 317–327. https://doi.org/10.1007/s00442-
012-2430-9
Soukup A, Tylová E (2014) Essential methods of plant sample preparation for light microscopy.
Methods in Molecular Biology 1080: 1–23. https://doi.org/10.1007/978-1-62703-643-6_1
SPPK D02 002 (2021) Standardy Péče o Přírodu a Krajinu: Obnova Dlouhodobě
Neobhospodařovaných Travních Společenstev (vč. likvidace náletových dřevin). AOPK
ČR, Prague, 39 pp. https://nature.cz/documents/20121/1200108/02002_OBNOVA_
DLOUHODOBE_NEOBHOSPODAROVANYCH_TS.pdf
Szymura M, Świerszcz S, Szymura TH (2022) Restoration of ecologically valuable grassland on
sites degraded by invasive Solidago: Lessons from a 6-year experiment. Land Degradation
& Development 33(12): 1985–1998. https://doi.org/10.1002/ldr.4278
Tang W, Zhu YZ, He HQ, Qiang S (2010) First report of Southern blight on Canadian goldenrod
(Solidago canadensis) caused by Sclerotium rolfsii in China. Plant Disease 94(9):
1172–1172. https://doi.org/10.1094/PDIS-94-9-1172B
Teixeira-Costa L, Davis CC (2021) Life history, diversity, and distribution in parasitic flowering
plants. Plant Physiology 187(1): 32–51. https://doi.org/10.1093/plphys/kiab279
Těšitel J, Fibich P, De Bello F, Chytrý M, Lepš J (2015a) Habitats and ecological niches of roothemiparasitic
plants: An assessment based on a large database of vegetation plots. Preslia
87: 87–108. https://www.preslia.cz/article/95
Těšitel J, Těšitelová T, Fisher JP, Lepš J, Cameron DD (2015b) Integrating ecology and physiology
of root-hemiparasitic interaction: Interactive effects of abiotic resources shape the
interplay between parasitism and autotrophy. The New Phytologist 205(1): 350–360.
https://doi.org/10.1111/nph.13006
Těšitel J, Mládek J, Horník J, Těšitelová T, Adamec V, Tichý L (2017) Suppressing competitive
dominants and community restoration with native parasitic plants using the hemiparasitic
Rhinanthus alectorolophus and the dominant grass Calamagrostis epigejos. Journal of Applied
Ecology 54(5): 1487–1495. https://doi.org/10.1111/1365-2664.12889
Těšitel J, Mládek J, Fajmon K, Blažek P, Mudrák O (2018) Reversing expansion of Calamagrostis
epigejos in a grassland biodiversity hotspot: Hemiparasitic Rhinanthus major does a better
job than increased mowing intensity. Applied Vegetation Science 21(1): 104–112. https://
doi.org/10.1111/avsc.12339
Těšitel J, Cirocco RM, Facelli JM, Watling JR (2020) Native parasitic plants: Biological control
for plant invasions? Applied Vegetation Science 23(3): 464–469. https://doi.org/10.1111/
avsc.12498
Unachukwu NN, Menkir A, Rabbi IY, Oluoch M, Muranaka A, Elzein A, Odhiambo G,
Farombi EO, Gedil M (2017) Genetic diversity and population structure of Striga hermonthica
populations from Kenya and Nigeria. Weed Research 57(5): 293–302. https://doi.
org/10.1111/wre.12260
van Hulst R, Shipley B, Thériault A (1987)Why is Rhinanthus minor (Scrophulariaceae) such a good
invader? Canadian Journal of Botany 65(11): 2373–2379. https://doi.org/10.1139/b87-322
Walder M, Armstrong JE, Borowicz VA (2019) Limiting similarity, biotic resistance, nutrient
supply, or enemies? What accounts for the invasion success of an exotic legume? Biological
Invasions 21(2): 435–449. https://doi.org/10.1007/s10530-018-1835-8
Tamara Těšitelová et al. / NeoBiota 90: 97–121 (2024)120
Wan J-Z, Wang C-J, Zimmermann NE, Li M-H, Pouteau R, Yu F-H (2021) Current and
future plant invasions in protected areas: Does clonality matter? Diversity & Distributions
27(12): 2465–2478. https://doi.org/10.1111/ddi.13425
Wang Y, Chen D, Yan R, Yu F, van Kleunen M (2019) Invasive alien clonal plants are competitively
superior over co-occurring native clonal plants. Perspectives in Plant Ecology, Evolution
and Systematics 40: 125484. https://doi.org/10.1016/j.ppees.2019.125484
Weber E, Jakobs G (2005) Biological flora of central Europe: Solidago gigantea Aiton. Flora
200(2): 109–118. https://doi.org/10.1016/j.flora.2004.09.001
Zhang S, Jin Y, Tang J, Chen X (2009a) The invasive plant Solidago canadensis L. suppresses
local soil pathogens through allelopathy. Applied Soil Ecology 41(2): 215–222. https://doi.
org/10.1016/j.apsoil.2008.11.002
Zhang CB, Wang J, Qian BY, Li WH (2009b) Effects of the invader Solidago canadensis on
soil properties. Applied Soil Ecology 43(2–3): 163–169. https://doi.org/10.1016/j.
apsoil.2009.07.001
Zhang Y, Yang X, Zhu Y, Li L, Zhang Y, Li J, Song X, Qiang S (2019) Biological control of
Solidago canadensis using a bioherbicide isolate of Sclerotium rolfsii SC64 increased the biodiversity
in invaded habitats. Biological Control 139: e104093. https://doi.org/10.1016/j.
biocontrol.2019.104093
Zopfi H (1993) Ecotypic variation in Rhinanthus alectorolophus (Scopoli) Pollich (Scrophulariaceae)
in relation to grassland management II. The genotypic basis of seasonal ecotypes.
Flora 188: 153–173. https://doi.org/10.1016/S0367-2530(17)32261-2
Supplementary material 1
Supplementary information
Authors: Tamara Těšitelová, Kateřina Knotková, Adam Knotek, Hana Cempírková,
Jakub Těšitel
Data type: docx
Explanation note: appendix S1: Location of source localities of hemiparasite seeds and
invasive host plants. appendix S2: Overview of the number of hemiparasite specimens
and their biomass in the experimental treatments. appendix S3: Overview of
host shoot counts and host biomass in the experimental treatments. appendix S4:
Photographic documentation of all pots representing the experimental treatments.
Copyright notice: This dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/neobiota.90.113069.suppl1
Root hemiparasites suppress invasive clonal plants 121
Supplementary material 2
Primary data table
Authors: Tamara Těšitelová, Kateřina Knotková, Adam Knotek, Hana Cempírková,
Jakub Těšitel
Data type: xlsx
Copyright notice: This dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/neobiota.90.113069.suppl2