Imperata brasiliensis

Name and classification

Imperata brasiliensis Trin.
Family Poaceae, Tribe Andropogoneae

Common names

Brazilian satintail, Brazilian blady grass

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 7–13 mm long. Glumes 2.4–4.5 mm long, lanceolate, pointed. Sterile lemma (if present) ca. 1 mm long, hyaline. Fertile lemma and palea shorter than glumes, hyaline. Styles 1.1–4.7 mm long, persistent, at least in part. Caryopsis oblanceolate, 0.8–1.5 mm long.

Identification considerations

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

Distinguishing characters:

  • Imperata brasiliensis: 2 bracts within glumes, rarely 3; 1 stamen in flower, filament dilated at base; styles 1.1–4.7 mm long
  • Imperata cylindrica: 3 bracts within glumes; 2 stamens in flower, filaments not dilated at base; styles 0.5–3.4 mm long

Molecular diagnostic tools have also been used to distinguish these species.

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 and portion of inflorescence axis (right)

spikelets; photo by Mark Thurmond

spikelets; photo by Mark Thurmond

spikelets

spikelets

spikelets

spikelets

caryopses in side view (upper left), dorsal view (upper right), and ventral view (lower right); photo 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

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