Panarctic Flora

630629-30 The Oxytropis varians aggregate O. jordalii, O. varians

Geography: North American.

Notes: Elven and Murray: American authors (e.g., Gillett et al. 2007) still assign several North American plants as races of Oxytropis campestris or at least as species of an O. campestris aggregate. Oxytropis campestris is a white-flowered (or rather pale yellow) European species. European treatments of O. campestris are not comparable to Asian and North American ones because they concern fairly small and local population groups within the general region from which O. campestris was described (Linnaeus: "Habitat in Oelandia, Germania, Helvetia"; lectotype chosen from the Swedish Baltic limestone island of Öland). The European variation is now mostly treated as a series of morphologically indistinct and closely related local races (e.g., in the north subspp. campestris, scotica, and sordida). The application of the name O. campestris to North American and Asian plants is problematic. The North American plants treated by Gillett et al. as varieties of O. campestris differ much more morphologically from each other, and from O. campestris in the European and type meaning, than do the European subspecies and some of the Russian species.

Our O. varians aggregate is northwestern North American and contains plants with white to pale yellow flowers. Yurtsev commented that the flowers of the North American species differ from the Eurasian ones by being without dark-lilac spot on the keel and the wings are narrow and not gibbose, and in addition they do not have colourless clavate processes on leaves and bracts, they sometimes have subverticillate leaflets, and they sometimes are at lower ploidy levels (2n = 16, 32), whereas only higher levels are recorded among Eurasian plants (2n = 48, 64, 96). Yurtsev considered the two major northwestern North American plants - O. varians and O. jordalii - to be outside the O. campestris aggregate. He did not agree with transforming the O. campestris aggregate "into a single species with countless subspecies as it greatly depauperates the presentation of taxonomic diversity". We agree and find the differences pointed out by Yurtsev to be significant taxonomically (perhaps except for the colour spot on the keel, see below). The northwestern North American plants should be recognized as species apart from O. campestris. The same might be the case with the northeastern North American plants and at least the majority of the Asian plants.

There is at present no way of handling this aggregate except for a traditional morphological one. Very little experimental data are available. The American investigation of Jorgensen et al. (2003) included only parts of the variation and applied few and perhaps not very appropriate molecular markers. The northwestern North American O. varians and O. jordalii were incidental to this investigation. In spite of applying the name O. campestris for some of the plants, none of the North American investigators have presented a critical comparison with European (and type) O. campestris. As long as Russian plants of the aggregate are treated as independent species, there would be a strong imbalance in the Checklist if we treated the even more deviating North American plants as races of O. campestris. We do not have the knowledge or experience needed for a critical evaluation of the proposed Russian species.