Panarctic Flora

671803 Boechera holboellii (Hornem.) Á. Löve & D. Löve

• Á. Löve & D. Löve, Bot. Not. 128: 513 (1976). - Arabis holboellii Hornem., Fl. Dan. 11, 32: 5, t. 1879 (1827). Type: Greenland: "Insulae Disco ad Jacobshavn", leg. C.P. Holbøll. Type probably the Flora Danica illustration.
• Arabis holboellii var. tenuis Böcher, Svensk Bot. Tidskr. 48: 38 (1954). Holotype (C): Greenland: "Itivdlinguaq sinus Søndre Strømfjord", material cultivated in Copenhagen and pressed 22. May 1951, leg. T.W. Böcher. - Boechera tenuis (Böcher) Á. Löve & D. Löve, Bot. Not. 128: 513 (1976).

2n= (1) 14 (2x). - Greenland. - Four reports, two for "tenuis".
(2) 21 (3x). - Greenland. - Three reports.

Geography: North American (Greenlandic): GRL.

Notes: The Greenlandic Boechera holboellii is replaced by related species in non-arctic parts of Canada and Alaska, e.g., the widespread B. retrofracta (Graham) Á. Löve & D. Löve.

Böcher (1954) specified several differential characters between the Greenland diploids and triploids, e.g., the diploids flower the first year and mostly only one year. He stated why he assumes that the Hornemann illustration of Arabis holboellii belongs to the triploids: large flowers, long fruits, large seeds. Böcher: "Therefore, it is highly probable that the type was triploid". Both diploids and triploids occur on Disko Island and in the probable exact type locality: Østerlien.

Löve and Löve (1975a, 1976a) distinguished between the diploids as Boechera tenuis and the triploids as B. holboellii s. str., based on Böcher (1954) who treated them as varieties. There might be some additional justification for this as the diploids may be sexual, whereas the triploids are agamospermous. However, they occur mixed in Greenland (elsewhere also with tetraploids). It is probably very difficult to tell them apart and to decide to which ploidy level a chosen Greenland population belongs. As they are largely sympatric and most probably results of autopolyploidy, we do not recognize two subspecies or species.