Cirsium greimleri

Cirsium greimleri, Greimler-Kratzdistel lit. 'Greimler's thistle', is a species of flowering plant belonging to the family Asteraceae.

Its native range is in Eastern Europe. It was only described as a separate species in 2018, and belongs to the minority species discovered through karyological analysis.

Etymology
Named after botanist Josef Greimler, whose chromosome count spurred the study that separated it from C. waldsteinii.

Distribution
It is found in the Eastern and Dinaric Alps. A partial but detailed map is designated ''Obr. 32b'' in Vavrinec 2020, which also provides distribution maps for its hybrids. A complete map was published in 2018, which includes flora-based ranges in the Dinarides, from which few precise coordinates exist yet.

The more precise ranges it has been found on include the Ennstal Alps, Rottenmann and Wölz Tauern, Seckau Tauern, Seetal Alps, Saualpe, Koralpe, Karawanks, Kamnik–Savinja Alps, Pohorje, Julian Alps, Snežnik, Srnetica, Klekovača,  Cincar, Vranica, Bjelašnica, Visočica, Treskavica, Zelengora, Jahorina, Komovi, Golija, and Kopaonik.

On its own, its distribution is similar to that of Cardamine waldsteinii, and somewhat similar to those of Achillea clusiana, Moehringia ciliata,  and Vicia oroboides.

When taken together with C. waldsteinii, its circum-Pannonian distribution is similar to that of Crocus vernus agg., including a polyploidy factor. Or to the acidophile species Hieracium transylvanicum. With less overlap, to Centaurea uniflora agg. or Pilosella alpicola. Including the Pontic and Caucasus, to Koeleria eriostachya. Including part of the Apennines, to Aposeris foetida.

Habitat
It is a subalpine and high montane species, found from 800 to 2000 m above sea level. It grows on the moist leeward slopes and on roadsides in valleys with running water in the more montane part of its range, but also in more open scree forests in the more subalpine part of its range.

In the Ellenberg system of indicator values, C. greimleri scores 9 for light availability, 5 for temperature, 9 for climatic continentality, 5 for soil moisture, 5 for soil pH, 8 for soil fertility, 0 for soil salinity. As calculated by these values, the coterminous Cirsium species with greatest ecological similarity was C. arvense, followed by C. heterophyllum and C. spinosissimum. The species is calcifuge, but does sometimes grow on calcareous substrates.

Description


Root is an oblique, cylindrical rhizome.

Plants grow to a height of 110-180 cm, with the exception of a form that grows to 30 cm identified in 1902 and designated C. greimleri f. depressum by Eugen Johan Khek, and sterile basal rosettes. Growth is erect but nodding below the capitula. Stems are shallowly ribbed. Stems are simple or have few branches. The form with branches was designated ''C. greimleri var. ramosum'' by Khek after he identified it in 1906. Their colour is green or reddish green but pilose or subglabrous at the base, whitish green and sparsely arachnoid in the middle, and white and densely arachnoid below the capitula. Leaves grow all along the stem.

Basal leaves are 11-24 cm wide and 1-2 cm longer than wide in mature specimens. Their morphology ranges from ovate, to orbicular, to deltate especially in younger leaves. Peduncular leaves amplexicaul, often auriculate. Their shallow pinnate lobes are doubly serrate to pinnatipartite, with weak yellowish to brownish-purple spinules up to 2 mm situated at the margins, subglabrous to scattered pubescent above and densely arachnoid-lanate below. All leaves are soft and herbaceous.

Flowers are capitula, each with 1-8 flowers, solitary or corymbosely terminally clustered, rarely solitary on 1-5 lateral pedicels. Involucre dimensions are 13-21 mm long at flowering. Phyllaries in 6-7 rows. Individual bracts bracts flare out from the bud, with distinct vittae, the outer and inner bracts being distinguished by the presence and absence, respectively, of a visible spine. Involucres are purplish brown to  purplish black.

Corolla length is 17-21 mm in hermaphrodites, 15-19 mm in females. At full anthesis, corollae average deep violet, but can be  greyish violet or even  ruby. During fading, corollae average dark purple, but can be  lighter,  dark magenta, or even  dark ruby or  dark violet. They ultimately fade to whitish, as does the (hermaphrodite) or  ochre synantherium. The style is always whitish except for the ruby shortly bi-lobed stigma, which fades to  deep crimson or  brownish-purple.

Strongly anemochorous, its fruits contain oblong, compressed, asymmetric greyish ochre achenes, 16-19 mm in hermaphrodites, 14-18 mm in females. They are attached to 4-5 mm pappi. The pappus is plumose, whitish, or stramineous.

Lookalikes

 * C. waldsteinii Rouy is genetically close and almost identical in appearance. In the field, the main distinguishing traits are lobe depth and flower colour. Although their basal leaves are roughly equal in width, the cauline leaves of C. waldsteinii are significantly wider, though the significantly deeper lobes of the latter may create the appearance of narrowness. The apparent broadness of C. greimleri leaves is distinctive within the genus. The corollae of C. waldsteinii are lighter in colour at any given stage, with little overlap in hue after opening (though both can be greyish violet at full bloom). This comparison must be made between flowers of roughly equal stage. The green colour of its stems below the capitula are slightly visible, unlike the completely covered C. greimleri.
 * C. hypoleucum DC.. Its nodding flowers are sometimes ruby red like those of C. greimleri, which is rare for the genus. The leaves of C. hypoleucum, sometimes resembling C. waldsteinii more than C. greimleri, are white-tomentose beneath, in contrast to the greyish-arachnoid leaves of C. greimleri. The involucral bracts of C. greimleri gradually become longer inward. The involucres of C. hypoleucum differ markedly in colour from those of C. greimleri, and the involucres themselves are narrower. The idumentum of subcapitular stem is sparser.
 * C. oblongifolium K.Koch. It has longer, more oblong leaves. Even the undersides of the leaves are glabrous.
 * C. pseudopersonata Boiss. & Balansa ex Boiss.. It is distinguished by its flower colour, more regular for the genus than that of C. greimleri, visible green through sparse idumentum of subcapitular stem, and glabrous leaf undersides.
 * C. sychnosanthum Petr.. Even the undersides of the leaves are glabrous.
 * C. uliginosum (M.Bieb.) Fisch.
 * C. carniolicum Scop.. Very similar to C. greimleri in vegetative stage, but with yellow to white flowers with tougher phyllaries and spiny sepals, visible green through pilosity of subcapitular stem, and more distinctive spines on upper cauline leaves with subglabrous undersides.
 * C. alpis-lunae Brilli-Catt. & L.Gubellini. A C. carniolum like species with spiny phyllaries and longer, stiffer leaf spines.
 * C. latifolium Lowe has similarly wide, whole leaves, but little resemblance otherwise.
 * A number of species have a similar flower colour but little resemblance otherwise: C. rivulare var. 'Atropurpureum' (Jacq.) All., C. borealinipponense Kitam., C. hachimantaiense Kadota, C. hidakamontanum Kadota, C. shimae Kadota, C. chokaiense Kitam., C. douglasii DC., C. occidentale (Nutt.) Jepson.
 * Such a flower colour can result from hybrids between yellow-flowered C. eristhales and purple-flowered species (such as C. alsophilum, C. palustre, C. pannonicum, C. rivulare). Hybridisation between the ancestor of C. greimleri and a yellow-flowered species like C. eristhales or C. carniolicum may be the reason the former has a different flower colour from C. waldsteinii.

Micromorphology
Stomatal guard cells are about 17 μm long and 9 μm wide.

Life cycle
Perennial.

Reproduction
Flowering is from late June to late July, to early August at sites of higher shade or altitude.

Plants are gynodioecious, some hermaphrodite and others female (rudimental synantheria, without developed pollen), in addition to sterile individuals that do not progress beyond rosette stage. Hermaphrodite flowers can be distinguished visually by the protrusion of their synantherium from the corolla, by colour of their synantherium, by the pollen pushed out by an elongating style at full anthesis (female synantheria lack pollen). Hermaphrodite synantheria are longer, at 7-9 mm, compared to female synantheria, at 4-6 mm. The same applies to styles, 20.0-25 mm in hermaphrodites, and 18-22 mm in females. Although both hermaphrodite and female stigmas can be straight, only female stigmas can be twisted, and usually are.

The smaller size of female achenes relative to hermaphrodite achenes in this species is unusual. Usually the reverse is the case, which has been explained as a compensation for the genetic disadvantage of females relative to hermaphrodites, and as a result of the absence of inbreeding depression. Suggested explanations for the aberrance in C. greimleri and C. waldsteinii include larger achene count, higher germanation rates, and lower infestation with achene predators like the Tephritidae and Curculionidae.

Hybridisation
C. greimleri is a diploid species with sporophytic chromosome number 2n=2x=34, without variation. Its somatic nuclear DNA size is about 1930 Mbp.

It readily forms hybrids, with the highest degree of promiscuity in its genus among the Cirsium species of the Pannonian Basin, leaving it vulnerable to genetic erosion through local imbalances in pollen production, leading to unidirectional geneflow. A similar situation exists for C. alsophilum, C. bertolonii, and C. carniolicum. Most populations consist of only a few to several hundreds of individuals, and only the Koralpe and Seetaler Alpen have known populations with over a thousand.

The following hybrids have been reported:
 * C. × juratzkae Reichardt ex Heimerl = C. greimleri × heterophyllum.
 * C. × przybylskii Eichenfeld = C. greimleri × oleraceum.
 * C. × reichardtii Juratzka = C. greimleri × palustre.
 * C. × stiriacum Fritsch = C. greimleri × rivulare.
 * C. × stroblii Hayek = C. greimleri × spinosissimum.
 * C. × sudae Michálková & Bureš = C. carniolicum × greimleri Melzer.
 * C. × scopolii E. Khek. ex Leuter et Zeitler = C. erisithales × greimleri.

Of the Cirsium species native to the northern part of its range, the greatest geographic overlap is with C. palustre, C. arvense, C. vulgare, and C. oleraceum. There is high overlap with C. eristhales and C. heterophyllum. There is moderate overlap with C. rivulare. There is low overlap with C. spinosissimum and C. carniolicum. There is very little overlap with, C. pannonicum, C. acaule, and no overlap with C. alsophilum, C. brachycephalum, C. canum. Though the lack of overlap with C. alsophilum, also a mountainous species with a presence in the Alps and Dinarides, is not certain at least for the Dinaric portion of its range.

Despite high range overlap, C. greimleri does not hybridise with C. arvense, which may be due to intersectional incompatibility.

Taxonomy
Internally, C. greimleri populations are more genetically distinct from one another than C. waldsteinii populations, whose intrapopulation diversity however is higher than C. greimleri. The high interpopulation diversity could have more to do with interspecific hybridisation, but it could also be solely the result of two effects of tetraploidy: one which slows genetic drift, and another which homogenises migrating populations more effectively such as during recolonisation following the Last Glacial Period. The low intrapopulation diversity of C. greimleri could be thanks to differences in the severity of glaciation between the Alps and the Carpathians.

Externally, a close relationship between C. greimleri, C. waldsteinii, and C. hypoleucum is suspected on morphological grounds. The relationship between C. greimleri and C. waldsteinii has already been confirmed genetically, although an allopolyploid origin of C. waldsteinii is strongly suggested. The relationship between C. greimleri and C. waldsteinii is so close that the intraspecific differences between females and hermaphrodites are higher than the interspecific differences.

C. waldsteinii was grouped with C. eristhales over C. greimleri in a 2023 paper, but the phylogeny was based on genome size, GC content, achene length, and guard cell length, rather than genetics.

Taxonomic history


Its holotype was collected by Petr Bureš at 1739 m from 47.27197°N, 14.40625°W in the Rottenmann and Wölz Tauern on 15 September 2015.

C. greimleri was considered part of C. waldsteinii until 2018.

All records before 2018 were published under other names, but the earliest published report of proleptic C. greimleri can be considered that of Host 1831, at Bürgersee near Judenburg, under the name Cnicus pauciflorus Kit.. Unpublished, the first record of what is now considered C. greimleri may have been a Tyrolian record in an 1807 catalogue by Johann Christoph Schleicher, but this is dubious.

First published under its present genus as Cirsium pauciflorum Spreng. by Anton Eleutherius Sauter following its discovery in Rottenmann Tauern.

In 1905, C. pauciflorum was recognised to be a younger homonym of C. pauciflorum Lam., which is now designated Carduus defloratus. Because of this, they assigned it a new name, C. waldsteinii.

In 2018, following the discovery that Alpine-Dinaric populations of "C. waldsteinii" were invariably diploid, whereas Carpathian populations were invariably tetraploid, together with physical and genetic evidence of separation, the two populations were split into two species.

Ecology
It grows in forests dominated by Acer pseudoplatanus, Alnus incana, Betula pendula, Corylus avellana, Fagus sylvatica, Larix decidua, Picea abies, Pinus cembra, and Sorbus aucuparia.

It is often found in association with other subalpine tall forbs, such as Adenostyles alliariae, Athyrium felix-femina, Calluna vulgaris, Cerastium lanatum, Chaerophyllum hirsutum, Chamaenerion angustifolium, Cicerbita alpina, Doronicum austriacum, Dryopteris filix-mas, Erigeron glabratus, Gentiana asclepiadea, Hieracium laevigatum, Hieracium lachenalii, Hieracium sylvaticum, Lactuca muralis, Peucedanum ostruthium, Phyteuma spicatum, Pleurospermum austriacum, Polypodium vulgare, Prenanthes purpurea, Senecio nemorensis agg., Senecio ovatus, Struthiopteris spicant, Telekia speciosa, Vaccinium myrtillus, Valeriana tripteris, Veratrum lobelianum, and Veronica urticifolia.

Among the shorter species it associates with are Aremonia agrimonoides, Artemisia umbelliformis, Cardamine enneaphyllos, Cardamine trifolia, Cerastium lanatum, Lamium orvala, Omphalodes verna, Sanicula epipactis, and Vicia oroboides.

It is forms part of the Pinion mugo type of Krummholz vegetation in the Dinarics.

It is sometimes an element of the Scabioso hladnikianae-Grafietum golakae Čarni association.

It is a rare element of the Calamagrostion arundinaceae association, the Huperzio-Alnetum viridis Mulgedio-Aconitetea Hadac & Klika ex Klika (1948) subassociation,  the Polysticho-lonchitis-fagetum rhododendrotosum hirsuti Boštjan & Rakaj subassociation.

It is also found in the associations EU 6170 Adenostylion, Cirsio cani-Filipenduletum ulmariae, Caricion davallianae, and Veronico-Calitrichetum.

Agriculture
The average TKW is 0.4 g, as calculated following the collection of seeds for the Millennium Seed Bank in 2014.