Imperata brasiliensis Trin.

Family: Poaceae,  Tribe: Andropogoneae

Common names:  Brazilian satintail

Disseminule:  Spikelet; disarticulation below glumes.

Description

Spikelets subterete, 3.5-5 mm long (excluding callus hairs), of 1 fertile floret and 1 (usually absent) basal sterile lemma. Spikelet callus with silky hairs 8-12 mm long. Glumes lanceolate, pointed. Sterile lemma (if present) ca. 1 mm long, hyaline. Fertile lemma and palea shorter than glumes, hyaline. Styles persistent, at least in part. Caryopsis oblanceolate, 0.8-1.5 mm long.

Identification remarks

Imperata brasiliensis is often confused with Imperata cylindrica (L.) Räusch.

Distinguishing characters:

Imperata brasiliensis: 2 bracts within glumes, rarely 3; 1 stamen in flower

Imperata cylindrica: 3 bracts within glumes; 2 stamens in flower

Distribution

South America, Central America, Mexico, and the West Indies, United States.

Habitat

Low altitudes, sandy and humid soils, pinelands; a weed of waste places and perennial crops.

General information

Imperata brasiliensis is an erect, tufted perennial grass with rhizomes, to 100 cm tall. It is abundant and weedy in Brazil; invading soybeans and Yerba mate (Ilex paraguariensis A. St.-Hil., which is used as tea.).

Spikelets and portion of inflorescence axis (right)

Spikelets

photo on left by Mark Thurmond

Caryopses in side view (upper left), dorsal view (upper right), and ventral view (lower right)

photo by Mark Thurmond

A, Spikelet; B, spikelet with bracts removed to show caryopsis; C, caryopsis in ventral view; D, caryopsis in dorsal view

drawing by Lynda E. Chandler