WOOLLY MORNINGGLORY, Mexican morningglory

Illustration

WOOLLY MORNINGGLORY-Ipomoea hirsutula Jacq. f.

DESCRIPTION-A prohibited noxious weed in Arizona, woolly morningglory is an annual with twining or trailing stems, up to 20 feet long, from a taproot system. All parts are hairy; it reproduces by seeds only. The leaves are of 3 principal shapes, on stalks 2 to 4 inches long. Some are unlobed, heartshaped, and very similar to the leaves of tall morningglory. Others vary from barely angulate to 3-lobed, to very deeply 3-lobed, with conspicuously heartshaped bases, 1 1/2 to 4 inches long. A few may be divided into 5 fingerlike lobes.

The flowers are blue, purple or whitish, and as in other morningglory flowers, open early in the morning, and close soon after the sun shines. They are 1 to 1 3/4 inches long, and in clusters of 1 to 5 on the long flower stalk. The 5-lobed calyx is conspicuously hairy at the base; these are 1/3 to 1/2 inch long, or in some plants up to 1 inch long.

The globeshaped seedpod is yellowish, and contains 4 seeds. The seeds are similar to those of scarlet morningglory, but larger, about 1/4 inch long, dark reddish brown to black, minutely hairy, and more flattened.

DISTRIBUTION-A native of tropical America, woolly morningglory is the most noxious of the Arizona species. Widely distributed throughout the central and southern part of the state, infrequent northward, it is abundant in cultivated lands. Especially troublesome in cotton, soybean, sorghum, and corn fields, roadsides, and sometimes in pinyon and yellow pine forests; from 100 to 7,000 feet elevation; flowering from May to November.

Around St. David (Cochise County) after the onset of the heavy summer rains, it covers more than 1,000 acres, mostly lying flat on the ground. It is one of the worst late cotton pests in the Safford (Graham County), Avra, Santa Cruz (Pima County), and Yuma valleys. Probably the major infestations occur in Maricopa and Pinal counties.

Copyright (c) 1972 The Arizona Board of Regents