An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




TREE TOBACCO-Nicotiana glauca Graham

DESCRIPTION-An evergreen, bluish green shrub or small tree, 6 to 12 (or to 21) feet high, which reproduces only by seeds. The stems are slender and loosely branching. The evergreen leaves are alternate, 1 1/2 to 6 inches broad, 3/4 to 2 2/3 inches long. They are bluish green, eggshaped, and hairless, but covered with a whitish powder which rubs off easily. The margins are smooth or slightly wavy.

The long tubular flowers are yellow, about 1 1/2 inches long, and are borne on large leafless branches at the ends of the stems. The flower tube is densely short hairy on the outside, and opens during the day. However, the 5 lobes are very short, so there is little spread. The calyx is unequally 5-toothed, and about 3/8 to l/2 inch long. The seedpods are brown, many seeded, 3/8 to l/2 inch long, somewhat eggshaped or oblong, on curving stalks so they hang downward. The kidneyshaped seeds are dark brown, about 1/16 inch long, with a honeycombed and roughened surface.

DISTRIBUTION-Tree tobacco is a shrubby weed of waste places, naturalized from South America. It grows in sandy or gravelly soils along roadsides, near cultivated areas, around old dwellings and ditch banks. It is common throughout the desert ranges in southern Arizona along streams, washes, and dry watercourses; 100 to 3,000 feet elevation; flowering practically the year around.

POISONOUS PROPERTIES-The leaves and young stems of tree tobacco are the most toxic parts of the plant. The plants are poisonous to all kinds of livestock and to humans. Although tobacco plants are distasteful, and where ranges provide ample forage, livestock usually do not eat them, frequent poisonings from these plants are reported.

Copyright (c) 1972 The Arizona Board of Regents

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