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DescriptionThis native grass is a summer annual with branching culms up to 2½' long; it produces several culms from the base that sprawl across the ground. The culms are light green, hairless, terete, and mostly covered by the sheaths of the leaves; their nodes are green or reddish green and glabrous. The blades of the alternate leaves are up to 6" long and 1/3" across; they are dull green, hairless, flat, broadest near the base, and linear in shape. The upper surface and margins of each leaf blade are scabrous. The sheaths of the leaves are dull green, mostly hairless, keeled, and somewhat flattened; a few white hairs may occur at the apex of some sheaths. Each culm and its upper branches terminate in individual racemes of flowers; each flower is enclosed in a spiny bur. Each raceme has a zigzag stalk up to 4" long with 4-20 burs on short pedicels. Each bur is about ¼" across (excluding the spines), yellowish green, and either globoid or globoid-ovoid in shape; it consists of 2 spiny rounded bracts that enclose 2-3 flowers. The outer surface of each bur has spines up to ¼" long and it is more or less pubescent. Each flower has 2 glumes and 2 lemmas; they are translucent with several fine green veins. The lemmas are lanceolate with a convex outer surface; they are about the same length as the bur. The glumes are smaller in size. The anthers and plumose styles of the flowers are exerted from the apex of the burs. The blooming period occurs from mid-summer to early fall. The flowers are wind-pollinated. After cross-pollination, the burs turn brown as their grains ripen. The root system is fibrous.