An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press

COULTER SPIDERLING, coulter boerhaavia

Illustration

FOUR O'CLOCK FAMILY-Nyctaginaceae

COULTER SPIDERLING-Boerhaavia coulteri (Hook. f.) Wats.

DESCRIPTION-An annual reproducing by seeds. The stems are erect or ascending, 1 to 2 1/2 feet high, or prostrate, radiating outward from the roots and ascending at the ends, 1 to 5 feet long. In rich soil, this plant may cover an area of 10 feet. The lower part of the stems may be very hairy, rarely glandular hairy, or covered by minute hairs. Sticky yellow bands on the upper stems are common particularly at maturity, but often none are present. The opposite leaves are unequal in size, eggshaped, usually hairless except along the stalks and sometimes the edges, and 1 to 4 inches long.

The flowers are pale pink, about 1/12 inch long, in clusters of 1 to 3, and scattered along the upper stem branches for 1 to 2 inches. The wedgeshaped fruits are hairless, with 5 broad ridges, and about l/8 inch long.

DISTRIBUTION-Found throughout most of the state except in the northeastern part. Especially common and annoying in late summer in southern Arizona in cultivated crops, gardens, roadsides, vacant lots, and overgrazed eroded ranges. Growing also in sandy washes, desert plains, and mountain foothills and slopes; 100 to 5,000 feet elevation; flowering June to October or November.

Copyright (c) 1972 The Arizona Board of Regents



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