An Illustrated Guide to ARIZONA WEEDS
The University of Arizona Press
HYSSOP SPURGE-Euphorbia hyssopifolia L.
DESCRIPTION-A slender erect hairless annual, often with many stiff spreading branches, 4 inches to 4 feet high in rich soil, reproducing only by seeds. The narrow oblong leaves are opposite, and vary greatly in size. A few leaves, scattered throughout the plant, are at least twice the size of others. They are 1/8 to 1 l/2 inches long, and l/8 to 2/3 inch broad, with short but sharp pointed teeth on the edges.
The 2 whitish inconspicuous stipules at the base of the leaf stalks are finely shredded along the edges. The greenish 3-lobed seedpods are hairless, about 1/12 inch long, and contain 3 seeds. The dark brown-oblong seeds, slightly less than 1/16 inch long, are 4-angled: 3 sharp and 1 rounded.
DISTRIBUTION-This native erect spurge is the most abundant and troublesome spurge in southern and central Arizona. It is a pest from late spring to late fall in all kinds of cultivated crops in the irrigated valleys. It is also a nuisance in gardens, lawns, waste places, often occupying large areas on deteriorating ranges in scrub oak and juniper associations. Frequent along sandy washes and slopes, 100 to 6,000 feet elevation; flowering May to November, mostly August and September.
Copyright (c) 1972 The Arizona Board of Regents