672101-02 The Draba micropetala aggregate D. micropetala, D. pauciflora
Geography: Circumpolar.
Notes: This aggregate is predominantly high-arctic, only rarely found as far south as the northernmost mountains of the boreal zone. It corresponds to Tolmachev's series Oblongatae which, if retained, perhaps should be renamed as the species name on which it was based - Draba oblongata R. Br. ex DC. - was misinterpreted and belongs to a species of the genetically and morphologically quite distant, white-flowered D. cinerea aggregate (see Mulligan 1974a). An appropriate name would be series Micropetalae.
Four names have been in frequent use in this aggregate: D. pauciflora R. Br. 1824, D. micropetala Hook. 1825, D. adamsii Ledeb. 1841, and the misapplied D. oblongata. The names D. pauciflora and D. micropetala are both based on types from the Canadian Arctic and belong to two different species. Draba adamsii was described from arctic Siberia and the name is a synonym of D. pauciflora. The name D. oblongata auct. has mostly been applied collectively for what now is recognized as D. micropetala and D. simmonsii (see below).
Draba micropetala and D. pauciflora have several features in common: petals very small, narrow, and pale yellow or reddish yellow; styles very short; fruits hairy; rosettes with broad leaves with a rounded to obtuse apex; and leaf hairs unusually coarse, simple and/or long-stalked branched (forked, irregular, cruciform, or few-branched stellate). They differ, however, in several characters in leaves, flowers, and fruits and are easy to keep apart. A single observed specimen combining their characters (from northeastern Greenland, O) had aborting fruits. The majority of the variation seen in Svalbard, northern Russia and Siberia, and in northern Alaska can be divided on D. micropetala and D. pauciflora even if there may be an additional deviating, very short-grown, high-arctic Eurasian plant not yet studied. For the probably related D. simmonsii, see below.
The comparatively low-ploid D. micropetala aggregate may have contributed parts of the genomic stock of the high polyploids. A morphological revision combined with molecular and cytological investigations is needed but, unfortunately, these cold-adapted plants are difficult to cultivate and study even in 'arctic' greenhouses.
Higher Taxa
- Draba [6721,genus]