Draba fladnizensis Wulfen in Jacquin
Brassicaceae (Cruciferae), Draba family.
Miscell. Austr. Bot. I: 147. 1779.
Wulfen in Jacq. (1779), Misc.
Austriac. 1: 147. PAF
Draba lactea Adams, Mém. Soc. Imp. Naturalistes Moscou 5: 104. 1817.
Vegetative morphology. Plants perennial herbs; 4–10 cm high; tufted. Taproot present. Caudex present (branched or unbranched). Aerial stems erect; glabrous, or sparsely hairy (glabrous or pubescent near base with mostly simple hairs). Leaves in a basal tuft (rarely with 1–2 small leaves); alternate; simple; existing for a single season or less. Petioles absent. Leaf blade bases attenuate. Blades 5–9 mm long; 2–2.5 mm wide. Blades herbaceous; circular; appearing single-veined. Blades adaxial surface glabrous, or scabrous. Blades adaxial surface hairs simple, unbranched and branched. Blades abaxial surface glabrous, or scabrous. Blade margins not lobed. Blade margins entire; with non-glandular hairs, or glabrous. Conspicuous hydathodes absent. Leaf apices acute.
Reproductive morphology. Flowering stems present. Flowering stems shorter than the leaves; without leaves; glabrous. Inflorescence racemose. Pedicels present. Flowers per inflorescence 3–6; small, less than 5 mm in diameter or length; actinomorphic. Calyx sepals 4; free; 2–2.5 mm long. Calyx green and purple; herbaceous; glabrous, or hairy. Petals free; longer than the calyx; 4; white; without contrasting markings; obovate; shallowly lobed; 3.5–4 mm long. Flowers bisexual. Stamens 6; filaments markedly unequal in length; free of the corolla; filaments glabrous. Anthers yellow; 0.5 mm long. Gynoecia superior. Carpels syncarpous; 2. Ovaries glabrous. Styles 1; 0.1 mm long. Stigmas per style 1. Placentation parietal. Ovules 8–10. Fruit stalk 4–6 mm long. Fruit without calyx persisting; dry; a silique; ovoid; distinctly flattened; dehiscent. Fruit 7–9 mm long; 2–3 mm wide; purple; glabrous, or hairy (rarely sparsely pubescent with unbranched trichomes). Styles remaining straight; persisting in fruit 0.2 mm long (or nearly obsolete). Seeds 8–10; 0.7–0.9 mm long; brown; with surfaces verrucose.
Chromosome information. 2n = 16. 16 (2x). - Heilborn (1927 Norway); Löve and Löve (1956b Iceland); Jørgensen et al. (1958 Greenland); Merxmüller and Buttler (1964 central Europe); Böcher (1966a Greenland and Svalbard); Knaben (1966a Norway); Knaben and Engelskjøn (1967 Norway); Buttler (1967 central and southern and northern Europe); Zhukova and Tikhonova (1971, 1973 eastern Chuk); Mulligan (1974b northwestern Canada Yukon, two counts); Engelskjøn (1979 Svalbard); Zhukova and Petrovsky (1980 western Chuk, 1984, 1987a north eastern Asia); Löve and Löve (1982 arctic Canada); Brochmann et al. (1993 Svalbard); Grundt (unpubl., Ala, Can,Greenland, Svalbard, Norway, Siberia, diploid in cytometry). Ploidy levels recorded 2x.
Distribution. Northern hemisphere distribution: circumpolar; Greenland, Canada, United States, Eurasia, Norden, Siberia, Asia. Arctic. Range in the Canadian Arctic Archipelago widespread. Common. Arctic Islands: Baffin, Devon, Ellesmere, Parry Islands.
Ecology and habitat. Substrates: hummocks; dry; calcareous, or circumneutral; gravel; with low organic content.
Notes. Draba fladnizensis is known as diploid, 2n=16,
from the entire geographical range.
The confusion between D.
fladnizensis and D. lactea results because these names are
synonymous. Draba lactea as it has been used lately is however distinct
from D. fladnizensis, both morphologically and genetically. Crossing
experiments within populations of D. fladnizensis (Grundt et al. in
prep.) have shown that several of these populations are inter-sterile (Grundt
personal communication 2001).
The diagnosis of D. lactea Adams fits
with two of the available original specimens but not with the third. The
specimens may well be from two species. The name should be typified by one of
the specimens (in LE or MW) fitting the diagnosis. Thereby it becomes a synonym
of the diploid D. fladnizensis. The hexaploid which until now has gone by
the name D. 'lactea' needs another name and the oldest available is D.
wahlenbergii Hartm. with available material (original Wahlenberg material in
UPS) for unambiguous typification.
Brochmann et al. (1993) found
interpopulational F1 hybrids in D. fladnizensis were entirely sterile,
suggesting that this predominantly inbreeding diploid species comprises at least
two sibling species, possibly isolated by genic barriers.
Draba
subcapitata (in Pilosae) and D. fladnizensis (in
Lacteae) are genetically and morphologically close (Scheen 1999, Scheen
et al. 1999, in prep.) and must belong to the same series if the series shall
have any taxonomic value. Both species are much more different from D.
'lactea' and from D. pilosa than from each other.
Illustrations. • Close-up of fruiting plant. Plant growing in rock crevice, a common habitat for this species. Note that the stem and siliques are glabrous and the siliques narrowly elliptic. The species has 0–1 leaves on the flowering stem, but usually 1. Russia, Altai. Collected/photographed by Hanne H. Grundt, pop. no 110, 2000 Oslo O.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
