Panarctic Flora

630703 Hedysarum americanum (Michx.) Britton

• Britton, Mem. Torrey Bot. Club 5: 201 (1894). - Hedysarum alpinum taxon americanum Michx., Fl. Bor.-Amer. 2: 74 (1803). Described from North America. - Hedysarum alpinum subsp. americanum (Michx.) B. Fedtsch., Trudy Imp. S.-Peterburgsk. Bot. Sada 19: 257 (1902).
• Hedysarum auriculatum Eastw., Bot. Gaz. (Crawfordsville) 33: 205 (1902). Type (GH): Alaska: the Seward Peninsula, Cape Nome, 1900, leg. F.E. Blaisdell.

2n= (1) 14 16 (2x). - Far East (N), Alaska, Canada. - Numerous reports.
(2) 28 (4x). - Alaska. - Johnson and Packer (1968).

Geography: Amphi-Beringian (E) - North American: RFE ALA CAN.

Notes: Yurtsev: I propose Hedysarum alpinum, H. americanum, and H. vicioides see below as three species. Hedysarum alpinum and H. americanum differ at species level. They can hardly be considered as vicariant taxa due to a gap (in the Russian Far East) of several thousand km between their ranges. There are constant differences between H. alpinum and H. americanum in, e.g., shape of leaflets and their mucros (short vs. elongate), shape of bracts and their length in relation to that of the pedicels (shorter in H. alpinum vs. somewhat longer in H. americanum), character of pubescence of inflorescence, and shape of calyx teeth (triangular vs. triangular-lanceolate). Despite similarity in morphotype, they are different in characters of nearly all organs and thus should not be considered conspecific.

Elven and Murray: Hedysarum alpinum L., Sp. Pl.: 750 (1753), was described from Siberia (Herb. Linn. 921.54 LINN is a possible lectotype according to Welsh) and does not reach the Arctic. The most current North American treatment (Gillett et al. 2007) is as a widely circumscribed H. alpinum and even to include the plants from the more arctic parts of the North American range in var. alpinum with an unnamed variety (?, Linnaeus 1753) in the Alps. Hultén (1968b) distinguished between the Asian plants as subsp. alpinum (including H. vicioides) and the North American ones as subsp. americanum. The gap between the Asian and North American parts of the range is not a valid argument against treatment as subspecies. We accept both parapatric and allopatric taxa as subspecies, sometimes even sympatric ones. However, if there is a morphological discontinuity in numerous features, as stated by Yurtsev, there is no reason to apply another rank than species. The H. vicioides mentioned above is, in our opinion, evidently different and acceptable as species.

Yurtsev: [Hedysarum auriculatum is] a critical taxon which can be considered either a diminutive race of H. americanum or a hybrid species (from H. americanum x H. hedysaroides subsp. tschukschorum).

Elven and Murray: Hedysarum auriculatum was described with type from arctic western Alaska and we have studied material from the type locality. Hultén (1968a) included it in the synonymy of H. americanum. We are reluctant to accept Yurtsev's suggestion that this might be a taxon, hybridogeneous or not. Material from the type area and from western Alaska (ALA) identified by Yurtsev as H. auriculatum belongs within our concept of H. americanum as a common arctic-alpine modification also present in, e.g., the Alaska and Brooks ranges. We can see no discontinuity in the variation pattern of H. americanum s. lat., or any influence from H. hedysaroides, in the material we have studied.