630620-30 The Oxytropis arctica-campestris groups
Notes: Elven and Murray: This may be the most complex group of arctic Oxytropis. Yurtsev (1986, PAF proposal, comments) emphasized flower colour as taxonomically significant and separated between assumed lineages with red/blue flowers, with white flowers with a dark blue spot on the keel, and with white flowers without spot. Jorgensen et al. (2003) investigated molecular markers (RAPDs, ITS) in twenty selected populations of northwestern North American plants which she identified as follows according to current American usage of names (Yurtsev's proposed names, when different, in brackets): the red/blue-flowered O. arctica var. arctica [O. arctica subsp. arctica + O. roaldii p.p.], O. arctica var. koyukukensis [O. koyukukensis + O. roaldii p.p.], and O. kobukensis; and the white-flowered O. arctica var. barnebyana [O. sordida subsp. barnebyana], O. campestris subsp. gracilis [O. varians], O. campestris subsp. jordalii [O. jordalii], and O. tananensis. The molecular grouping followed neither flower colour nor the previously named species, subspecies, or varieties. Red/blue and white-flowered O. arctica consistently grouped together but also together with several other named taxa. Yurtsev separated them on different assumed lineages due to the flower colour difference. On the other hand, plants on the Alaskan north coast differed from those on the west coast irrespective of whether they were identified as red/blue O. arctica s. str. and O. roaldii or white O. arctica var. barnebyana. Oxytropis koyukukensis (in the O. arctica group of Yurtsev) partly kept apart, partly grouped closely with western Alaskan O. arctica (ncl. barnebyana). Yurtsev considered O. gracilis (or O. varians) and O. jordalii a well separated group. These white-flowered species, however, associated closely with all 'types' of O. arctica incl. barnebyana (both red/blue and white). The white-flowered O. tananensis with semi-verticillate leaflets kept apart in RAPDs but not in ITS where it grouped closely with the white-flowered O. jordalii with non-verticillate leaflets.
Jorgensen's study should be supplied with more populations, more taxa, more areas, and especially more and perhaps more discriminating molecular markers before molecular data can be utilized in a revised taxonomy. However, the results as they stand throws doubts on the established taxonomy (both the American and the Russian) and especially on one of the main tenets of Yurtsev's taxonomy, the importance of flower colour for separation of evolutionary lineages. It rather points towards the group as a polyploid reticulum of several lineages, each combining red/blue and white flowers. In spite of this, there is at present no consistent alternative to Yurtsev's proposal and we have made only a few changes compared with it.
Higher Taxa
- Oxytropis [6306,genus]