Panarctic Flora

672120-24 The Draba nivalis aggregate D. chamissonis, D. lonchocarpa, D. magadanensis, D. nivalis, D. palanderiana

Geography: Circumpolar-alpine.

Notes: Grundt and Elven: The Draba nivalis aggregate consists of small and slender Drabas characterized by a mostly dense cover of regular, very small and many-branched stellate hairs on almost all vegetative parts (D. magadanensis excepted). Draba palanderiana and D. magadanensis have pale yellow petals and comparatively large flowers adapted to outcrossing. The others have white petals and small flowers adapted to inbreeding. All species mostly have glabrous fruits (pubescent fruits are considered an aberration within populations). The core of the aggregate (D. chamissonis, D. lonchocarpa, D. nivalis, D. palanderiana) is kept together by several synapomorphies. The aggregate includes diploids and some low polyploids and is paraphyletic from molecular evidence. It constitutes a clade but that clade also includes D. lactea not included in the aggregate by us due to deviating morphological characters.

Three of the core taxa - D. nivalis, D. lonchocarpa, D. palanderiana - have been well investigated for morphology (Mulligan 1974b), cytology (Mulligan 1974b; Grundt et al. 2005b), and isoenzymes, RAPDs, sequences of two genes, and infraspecific crossing abilities (Grundt et al. 2004, 2006). They are distinct both in morphology and in molecular markers, without any transitions, and are evidently three species. Draba chamissonis is very similar to D. nivalis morphologically and also shares its ITS sequences (the only molecular markers studied in D. chamissonis) with a major part of the D. nivalis studied but not with the other studied species (Grundt unpubl.). Draba magadanensis is similar to D. palanderiana in morphological features except for the pubescence but has not been investigated for any molecular markers.