An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press

LAMBERT CRAZYWEED, Lambert loco, point loco, purple loco, white loco


PEA FAMILY-Leguminosae

LAMBERT CRAZYWEED-Oxytropis lambertii Pursh var. bigelovii Gray

DESCRIPTION-A stemless hairy perennial from a woody taproot system with a branching base, which reproduces only by seeds. There are no true stems, and all the leaves come from the base of the plant. These leaves are 3 to 10 inches long, and divided once into 7 to 9 pairs of silky hairy leaflets 1/2 to 1 inch long.

The many flower stalks are 4 to 16 inches long, nearly naked 2/3 of their length, and bear numerous flowers on the upper part. The showy flowers are pealike, commonly purple or sometimes white, 1/2 to 1 inch long. The oblong woody seedpods are hairy, 3/4 to 1 1/4 inches long, including the slender beak about 1/4 inch long. The reddish brown, somewhat kidneyshaped seeds are angular and flattened, about 1/12 inch long.

DISTRIBUTION-Lambert crazyweed is a native weed, growing in sandy or open slopes and plains in the yellow pine forests. It is very common and abundant in some areas where it has increased and spread on overgrazed and "cheeped out" areas in the open pine ranges of eastern Arizona, from Apache to Coconino counties, and in the mountains of Greenlee, Graham, and Cochise counties; 5,000 to 8,000 feet elevation; flowering June to September.

POISONOUS PROPERTIES-Lambert crazyweed and a few species of Astragulus (locoweeds) cause "locoism" in horses, cattle, and sheep. Poisoning in Arizona occurs principally among cattle in the spring. Losses have been reported from Navajo county, near Showlow, Snowflake, and Holbrook; also in the Pinaleno Mountains, Graham County.

Blue loco (Astragalus lentiginosus Dougl. var. diphysus [Gray] Jones) might also be involved, since it is known to be poisonous, and has about the same distribution as Lambert crazyweed. Cattle losses caused by locoweed are also reported from the Canelo Hills, Sonoita, Patagonia, and Elgin areas in Santa Cruz county. These are probably due to sheep loco (Astragalus nothoxys Gray), since Lambert crazyweed does not occur there. For a full discussion of locoweed and crazyweed poisoning in Arizona, see Livestock-Poisoning Plants, by Schmutz, Freeman, and Reed.

Copyright (c) 1972 The Arizona Board of Regents

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