An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




HORSE PURSLANE-Trianthema portulacastrum L.

DESCRIPTION-Horse purslane is a fleshy succulent annual with a shallow root, reproducing only by seeds. At first the weak diffusely branched stems are erect, but seldom higher than 1 foot (or to 2 or more feet in competition for light, as in a soybean field) before spreading, and finally reclining on the ground, 1 to 5 feet long. The bright green fleshy oval leaves are opposite, the pairs very unequal in size, 1/2 to 3 1/2 inches long including the stalks which are widened and 2-toothed at the base, and are 1/3 to 1 2/3 inches broad.

The flowers have 6 to 10 stamens, and 5 flower parts about 1/3 inch long. These flowers are rose purple within, and each bears a thickened hornlike tip on the back. The flowers occur singly or a few together in the leaf and branch axils, and are open only in the mornings. The small seedpod is topshaped, with the upper part thickened, 2-crested and falling away as a lid when the 1 to 5 seeds are mature. The thick blackish seeds are squarish or somewhat heartshaped, about 1/12 inch broad, and covered by whitish wavy ridges.

DISTRIBUTION-Horse purslane is a tropical and subtropical American plant. It is a troublesome annual weed common in sorghum, citrus, and cotton; up to 4,000 feet elevation. It is also common in alkaline flats, roadsides, lawns, and waste places; flowering May to November. This plant is a host for the beet leafhopper.

Copyright (c) 1972 The Arizona Board of Regents

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