Panarctic Flora

340701g Bromopsis pumpelliana subsp. dicksonii (W.W. Mitch. & Wilton)

• Bromus pumpellianus subsp. dicksonii W.W. Mitch. & Wilton, Brittonia 18: 163 (1966). Holotype (ALA!): Alaska: the lower Yukon and Kuskokwim river valleys, Bishops Mountain, next to Galena, 04. Aug. 1951, leg. J.G. Dickson LY 57-19. - Bromopsis dicksonii (W.W. Mitch. & Wilton) Á. Löve & D. Löve, Bot. Not. 128: 501 (1976).

Geography: American Beringian: (ALA).

Notes: Elven and Murray: Bromus pumpellianus subsp. dicksonii was accepted by Soreng et al. (2003, at the weaker "acceptance level 2") and by Pavlick and Anderton (2007). It was originally described as a tetraploid species (Wilton 1965, as Bromus "X") or race from a locality on the lower Yukon River in Alaska (Mitchell and Wilton 1966), and the extent of its range is unclear. The type material is not very different from Bromopsis pumpelliana s. str.: more or less rhizomatous (stated to be tufted), sheaths glabrous, leaves glabrous on the lower surface and sparsely pilose on the upper one, nodes glabrous, ligula short (as in other races and contrary to the original diagnosis), panicle very open (more so than in most parts of B. pumpelliana), glumes very sparsely pilose (mainly marginally) to pubescent (middle), lemmas pilose marginally and along midvein, otherwise pubescent, and awn 6-10 mm. The most deviating character is the large, open panicle but similarly large panicles are seen in other plants of the B. pumpelliana group. Wilton (1965) reported interfertility between tetraploid B. "dicksonii" and octoploid B. pumpelliana s. str., especially with the octoploid as maternal. Note that tetraploids and also hexaploids are known from Siberia and Chukotka within what there is considered as the B. pumpelliana complex. We are reluctant to accept "dicksonii" as a species or subspecies apart. However, the morphological differences between the tetraploids and octoploids should be investigated further.