VICIACEÆ (PEA FAMILY). =Aragallus lambertii.=—The Lambert, or stemless loco weed, is, next to the following species, the best known representative of a large group of closely related plants which are native to the western half of the United States, and are known as loco weeds on account of the peculiar excited condition which they induce in animals that eat of their leaves. Horses and cattle are both affected, but the chief damage is done to horses. After being permitted to graze on any of these plants the animal acquires an unnatural appetite for them, and soon refuses all other kinds of food. It rapidly becomes unmanageable, shows brain symptoms, and finally dies from lack of proper nourishment. =Astragalus mollissimus.=—This, the woolly loco weed, is perhaps the best known of all the loco weeds. It is the species most abundant in Colorado, where from 1881 to 1885 nearly $200,000 was paid out in bounties in an attempt to exterminate it. The plant is still abundant in that State, and reports of the damage done by it continue frequent. Specimens of the three following species of _Astragalus_ have been forwarded to the Division of Botany with the information that they were causing great financial loss in the districts noted. It is quite probable that other species are dangerous also. [Illustration: $1] [Illustration: $1] [Illustration: $1] POISONING BY WHITE LOCO WEED (ARAGALLUS SPICATUS). [Illustration: $1] [Illustration: $1] This is an erect tufted perennial, 4 to 18 inches high, with pinnately divided leaves and spikes of white or cream-coloured flowers, shaped like those of the pea. The pod is one-celled, and when shaken produces a rattling sound, which gives the plant the name of “rattle weed” in some localities. The white loco weed is exceedingly common throughout Montana. It occurs most abundantly on the northern slopes of foothills up to an altitude of about 8,000 feet. Its preferred habitat is for the most part in rather dry situations. The habit of the plant varies in different parts of Montana. In some localities the flowers are pure white, while in others they are decidedly yellow. In Colorado the plant which is most ordinarily known as loco weed is _Astragalus mollissimus_, while in Montana the species already named is perhaps most important; but there are others which have a rather wide distribution and are known to produce the same effects. Among these may be mentioned _A. splendens_, _A. lagopus_, and _A. besseyi_.