An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




BARESTEM LARKSPUR-Delphinium scaposum Greene

DESCRIPTION-A grayish green perennial which reproduces by seeds and from clusters of dark hard woody roots, often forming large or small colonies. The stems are solitary or few, 1/2 to 2 1/2 feet high. The leaves are divided into narrow segments, and mostly clustered at the base.

The flowers are usually an intense royal blue, but are sometimes lighter blue or nearly lavender. They look exactly like the cultivated larkspurs, with the characteristic long spur at the base. The seedpods, 3/8 to 3/4 inch long, split into 3 parts when the many seeds are mature.

DISTRIBUTION-Barestem larkspur is the most widespread larkspur in Arizona. Found in sandy or gravelly soil on desert mesas and foothills in Apache, Navajo, Coconino, Mohave, Yavapai, Gila, Maricopa, Pinal, Graham, and Pima counties; 2,000 to 5,000 (rarely 8,000) feet elevation; flowering March to April, or May and early June in the higher elevations.

Larkspurs, where sufficiently abundant in Arizona, are a serious cause of livestock poisoning. Cattle losses from larkspur poisoning occur very early in the spring. Santa Cruz County, particularly in the Sonoita area, Yavapai County, in the vicinity of Prescott, and Coconino County, near Seligman and between Williams and Flagstaff are known trouble areas.

The 9 native Arizona larkspurs may be divided into tall larkspur (2 1/2 to 6 feet tall, of high moist elevations, flowering in late summer) and low larkspur (1/2 to 2 feet tall, of dryer plains and foothills, flowering in the spring). All species should be regarded as poisonous. The tall larkspurs may be more poisonous, but the low larkspurs are more abundant, and probably more responsible for the cattle poisoning.

WOOTON PLAINS LARKSPUR-Delphinium virescens Nutt. subsp. wootoni (Rydb.) Ewan

Very similar to barestem larkspur, but the leaves and stems are covered by fine incurved white hairs. Sometimes a few leaves are found just above the basal cluster. The flowers are whitish or pale lavender blue, fading buff, and the lower petals are white with conspicuous white hairs.

Found in southeastern Arizona on open slopes and plains in Graham, Cochise, Santa Cruz, and Pima counties; 3,800 to 6,000 feet high; flowering April and May. Wooton plains larkspur is probably the cause of larkspur poisoning in Santa Cruz County.

Copyright (c) 1972 The Arizona Board of Regents

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