A wild and crazy rarity residing in a small corner of Alberta, Oxytropis lagopus is a somewhat toxic member of the pea family
If you are not a rancher, then there’s a lot to love about this crazy plant, this “locoweed.” For some, it is its delicate colourful flowers. For others, it is its silken and silvery herbage. Others will point to its rarity. We like it for its name, hare-footed locoweed, though we also like the alternative names: hare’s-foot point-vetch and rabbit-foot crazyweed.
Its full and proper name is Oxytropis lagopus. The first part is derived from the Greek words oxus, meaning sharp, and tropis, for “keel,” and refers to the sharp tip of the bottom conjoined petals (or keel) of the flower. Lagopus is derived from the ancient Greek word lagos, meaning “hare,” plus pous for “foot” — though there is nothing particularly about it that resembles a hare’s foot. (Oddly, the same word is also the generic name for the ptarmigan, whose foot, admittedly, is vaguely lapine.)
As to where loco, Spanish for “crazy,” comes from, some Oxytropis species synthesize swainsonine, a chemical
compound that, as ranchers and vaqueros everywhere know, in large and sustained quantities causes intoxication in cattle, horses and sheep; they start acting loco. The medical condition is actually known as locoism (also locoweed disease, or pea struck in Australia); symptoms include aggression, hyperactivity, difficulty walking, drooping head and loss of coordination.
A member of the pea family, the hare-footed locoweed is a small tufted plant standing up to 13 cm tall with 5 to 15 leaves topped by 15-mm purple-blue flowers with five petals (they bloom mid-april to August). The seed pods measure up to 15 mm long and expand at maturity. The distinctive keels noted above differentiate this species from the similar-looking though more common and benign milk vetch, as do the basally attached silky hairs.
In Canada, the hare-footed locoweed is found in southwestern Alberta near the Montana border, in a 2,700-sq.-km grassland and plateau carved with ravines and ridges by the Milk River (unusual for Canada, it is part of the Mississippi River’s massive drainage basin). Called the Milk River Ridge, the sensitive area is home to several endangered species of birds, fish, amphibians and plants and is an important habitat for deer, pronghorn and many birds of prey. Locoweed grows in strips along upper slopes or plateau rims of the area’s steep ridges, in well-drained sandy or gravel soils.
Confined in Canada to this small area, Oxytropis lagopus is listed as “of special concern” under the federal Species at Risk Act. Gravel quarrying and other development poses the greatest threat to its habitat. A perennial that reproduces through pollination, the species relies on bumblebees. With the dramatic decline in the North American bumblebee population, the future of the species is in doubt.