A New Hybrid in Pilosella (Asteraceae) from the Tambov Region, European Russia

A New Hybrid in Pilosella (Asteraceae) from the Tambov Region, European Russia

Ann. Bot. Fennici 48: 69–73 ISSN 0003-3847 (print) ISSN 1797-2442 (online) Helsinki 31 March 2011 © Finnish Zoological and Botanical Publishing Board 2011 A new hybrid in Pilosella (Asteraceae) from the Tambov Region, European Russia Alexander N. Sennikov Botanical Museum, Finnish Museum of Natural History, P.O. Box 7, FI-00014 University of Helsinki, Finland; and Herbarium, Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov str. 2, RU-197376 St. Petersburg, Russia (e-mail: [email protected]) Received 29 June 2009, revised version received 17 Oct. 2009, accepted 20 Oct. 2009 Sennikov, A. N. 2011: A new hybrid in Pilosella (Asteraceae) from the Tambov Region, European Russia. — Ann. Bot. Fennici 48: 69–73. A new hybrid combination Pilosella onegensis Norrl. ¥ P. praealta (Vill. ex Gochn.) F. Schultz & Sch. Bip. is recognised on the basis of its intermediate morphological char- acters, and described under a new binomial name, P. ¥ tambovica Sennikov. All old records of P. caespitosa (Dumort.) P.D. Sell & C. West and many such of “Hieracium nestleri Vill.” from the Tambov Region of European Russia are found referable to P. onegensis. The taxonomy of the genus Pilosella (Aster- (Schuhwerk & Fischer 2003, Bräutigam & Greu- aceae) is heavily complicated with a combina- ter 2007). tion of sexual and apomictic (aposporic) type of A group of Pilosella species with black reproduction. Very few primary species of this styles, cymose inflorescences with yellow or genus exist on the diploid level; they are presum- orange flowers, hairy, mostly rosulate leaves, ably entirely sexual (Merxmüller 1975). The dip- and fragile spreading flagellae (sect. Pratensina) loids in addition to some polyploids are consid- includes a single sexual diploid species, Pilosella ered as “basic” species in Pilosella, presumably onegensis Norrl. (Hieracium onegense (Norrl.) of non-hybrid origin (von Nägeli & Peter 1885, Norrl.). This species has a mostly east-European Zahn 1923), and only 20 such species are cur- distribution with occurrences in central Europe rently recognised in Europe (Bräutigam & Greu- and western Siberia (Schljakov 1989). The most ter 2007). Numerous intermediate taxa share a peculiar attributes of this taxon are its pubes- combination of diagnostic characters of two or cence, rather dense and characteristically short more species and are treated as putative hybrids on its dark-green leaves, reaching 1 mm only (von Nägeli & Peter 1885, Zahn 1923). These on the upper surface of the lamina, and its short hybrids were recognised in crossing experi- (6–7 mm long) phyllaries (Sennikov 2000). ments, or hypothesized from field observations Whereas numerous hybrid combinations are or on purely morphological grounds (e.g. Peter recognised within Pilosella, just a single hybrid 1884, von Nägeli & Peter 1885, Zahn 1923). The with P. onegensis is currently recorded with con- system of hybrid combinations in Pilosella was fidence (Bräutigam & Greuter 2007). Such a sit- developed by Zahn (1923) and recently updated uation is caused by the fact that this species was 70 Sennikov • ANN. BOT. FENNIcI Vol. 48 generally neglected by the hieraciologists of the botanical exploration (Koschewnikoff 1876, “central European school” who treated it at the Litwinow 1888). These records are found based subspecies level, either as Hieracium caespito- on the specimens of P. onegensis. Most of the sum Dumort. subsp. brevipilum (Naeg. & Peter) earliest records of “Hieracium nestleri Vill.” P.D. Sell or Pilosella caespitosa (Dumort.) P.D. and H. vaillantii Tausch (Koschewnikoff 1876, Sell & C. West subsp. brevipila (Nägeli & Peter) Litwinow 1888), and even the major part of P.D. Sell & C. West. Another difficulty is the Zahn’s exsiccata of Hieracium glomeratum Fr. fact that the hybrids with participation of various subsp. detonsum (Norrl.) Naeg. & Peter (Zahn yellow-flowering taxa of sect. Pratensina may 1905) are also proven to be misidentifications of look rather similar, and a thorough treatment of P. onegensis. the local taxa is always needed to exclude a pos- A single plant that appeared exactly inter- sible influence of other related species. mediate in its morphology between P. onegensis The exceedingly high level of intraspe- and P. praealta (Vill. ex Gochn.) F. Schultz cific variability in the polyploid “basic” taxa & Sch. Bip. [the latter name accepted after of Pilosella led the early adepts of the “central Schljakov (1989) and Sennikov (2000)] was European school” to the recognition of numer- detected in the collections. It has the habit of P. ous infraspecific taxa (Zahn 1923). Introgressive praealta but lacks spreading stolons, its leaves hybridisation possibly accounts for this variabil- are yellowish-green (not glaucous) with more ity, usually involving all species-specific mor- numerous dark-based hairs along the margins phological characters (Sennikov 2003). In con- and the central nerve beneath, the stem hairy and trast to these agglomerates of morphologically stellate throughout with the lowermost internode similar forms, P. onegensis, being a primary abbreviated and densely pilose, the inflorescence diploid species, displays a strikingly low level branches densely covered by the stellate pubes- of intraspecific diversity, with very few names cence, numerous short glandular hairs and long falling into its synonymy (Sennikov 2003 and simple hairs, the phyllaries dark with whitish unpubl. data). The hybrids of this species can be margins (well-visible on the short bracts at the immediately recognised as exceeding its usual base of capitula), and the black styles. On the variability. other hand, this plant readily differs from P. During a revision of all available herbarium onegensis in the habit and the shape of its material (ca. 100 specimens) for the forthcoming pale subglabrous leaves. The hybrids between Flora of the Tambov Region (European Russia), P. praealta and P. floribunda, regularly col- kept at the Herbaria of the Komarov Botani- lected and therefore apparently not uncommon cal Institute (LE) and Moscow State University in eastern Europe, easily differ in a much lesser (MW), only two species of Pilosella with black hairiness of the stems and in the visibly glaucous styles were found occurring in that territory, leaves (both these parents are subglabrous), and namely P. onegensis and the stabilised hybrid frequently in the presence of ascending shoots. P. floribunda (Wimm. & Grab.) Fr. These two The hybrid combination P. onegensis ¥ P. taxa can be readily distinguished by the colour praealta has not been formally recongised yet and pubescence of leaves, the leaves being dark- and is given a new binary name here, P. ¥ tam- green and hairy above in P. onegensis and glau- bovica Sennikov. The specific epithet tambovica cous-green and glabrous or subglabrous above in is chosen to acknowledge the occurrence of P. floribunda. All these characters are traceable this hybrid in the Tambov Region of Russia, from the hybrid forms, when such are found even though it is apparently not restricted to (usually nearby their parents). this region, because its parental taxa have quite Pilosella caespitosa, a central-European spe- widely overlapping distribution areas and the cies with long (up to 2 mm) hairs on the upper hybridisation in this genus is common every- side of its leaves, has been reported under its where. synonym Hieracium pratense Tausch from the The descriptive terminology of pubescence Tambov Region from the very beginning of its follows Schljakov (1989). ANN. BOT. FENNIcI Vol. 48 • A new hybrid in Pilosella from the Tambov Region, European Russia 71 Fig. 1. The type specimen of Pilosella ¥ tambovica. Pilosella ¥ tambovica Sennikov, sp. hybr. ab altera foliis laetioribus subglabris & habito nova (P. praealta (Vill. ex Gochn.) F. Schultz differt. & Sch. Bip. ¥ P. onegensis Norrl.) (Figs. 1 Type: Russia. Tambov Region: Rzhaksa District, 6 km S and 2) of Rzhaksa Village, meadow slope of a gully, 30.V.2004 A. P. Sukhorukov (LE, holotype). Planta fortasse hybrida inter P. praealtam & P. onegensem intermedia, a prima caule foliisque Rosulate plants with solitary erect stems, pilosioribus, inflorescentiae ramis dense stellatis spreading flagellae missing. Stems 45–55 cm, & glandulis pilisque multioribus, stylis nigris; unbranched outside inflorescence, light-green but 72 Sennikov • ANN. BOT. FENNIcI Vol. 48 Fig. 2. Phyllaries (left) and inflorescence branches (right) from the holotype ofPilosella ¥ tambovica. Scale bar: 2 mm. violet in ca. 1 cm at base, with numerous simple irov combined P. caespitosa and P. floribunda hairs 3–4 mm long densely condensed at stem altogether and set no distinction between the base, black-based in upper part, totally pale in hybrids with participation of P. caespitosa, P. middle, and violet-based at base of stem, with floribunda and P. onegensis. The taxa reported black glandular hairs dispersed in upper part of by Tikhomirov as hybrids between P. onegensis stem, finely stellate throughout. Leaves yellow- and P. praealta have been previously considered ish- to pale-green, basal 3–4, oblanceolate, attenu- as hybrids with P. caespitosa or combined with ated to base, subacute at apex, with sparse rigid various taxa of P. sect. Praealtina as “microspe- black-based simple hairs along margins and mid- cies” or synonyms (Sell & West 1976, Schljakov vein beneath, finely stellate beneath, cauline 2, sit- 1989). However, it is still not impossible to uated in basal third or half of stem, sublanceolate,

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