This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds and by rootstocks.
Time of bloom: June to July.
Seed-time: July to August.
Range: Nebraska, Wyoming, and the Dakotas.
Habitat: Plains; pastures and meadows.
Lupines furnish western stockmen with much nutritious green forage and good hay. They are especially valuable in the late fall, when they remain green and succulent after grasses and other plants have become dry. But observation and experiment have demonstrated that, during the time of seed development, Lupines are very injurious to grazing animals, particularly sheep. Cattle usually reject the seeds, selecting the leafy parts of the plant which seem to contain little, if any, of the poisonous property; but the seeds and pods contain a dangerous quantity of a substance known as lupinotoxin, which causes a disease called lupinosis, the acute form of which may cause death in a few hours, sometimes less than one. Sheep seem to have a preference for the pods, often nibbling them from the plants and leaving the rest. Cornevin states that in 1880 more than fourteen thousand sheep died of this complaint in Germany, where Lupines of several species are much used as forage and for reclaiming sandy soils where clover does not readily "catch."
This is rather a large species, one to nearly two feet tall, the stems erect and branching, covered with fine, appressed, silky hairs which give it a glaucous appearance. Leaves on rather long petioles, the leaflets seven to ten, about two inches in length, short-spatulate, usually obtuse, smooth above but appressed hairy beneath, giving a glaucous appearance. Racemes long and graceful, the flowers large and not crowded on the stalk, pale blue or purplish, the standard having a conspicuous blotch of darker color. Pods numerous, covered with appressed hairs, two- to five-seeded. (Fig. 162.)
Prevent seed production by cutting while in early bloom or even before flowering. At times even the green fodder becomes dangerous, causing bloat and other symptoms of unwholesomeness.
Fig. 162. - Nebraska Lupine (Lupinus plat-tensis). X 1/4.
In Europe, where stall-feeding of farm animals is more commonly practiced than in this country, it has been found that Lupine fodder is rendered entirely innocuous by steam heating under pressure, which at the same time makes it much more palatable and fattening. Dry heat does not destroy the poison. In many places it would be advisable to put the ground under cultivation with the purpose of replacing these plants by some less dangerous member of the Legume Family.