Monographs Details: Axonopus rivularis G.A.Black
Authority: Maguire, Bassett & Wurdack, John J. 1957. The Botany of the Guiana Highland -- Part II. Mem. New York Bot. Gard. 9 (3): 235-392.
Family:Poaceae
Description:Latin Diagnosis - Perennis, foliis laxis; culmi 75-90 cm longi, 1-2 mm crassi, teretes vel vix compressi; nodi 1-2, pilosi; vaginae 10-35 cm longae, superiores longiores, 1-3 mm latae, dorso rotundatae, cataphyllis 1-3 mm longis, ad basin nonnumquam a culmis solutae, internodiis breviores, glabrae, summo ciliatae; ligula 0.3-0.4 mm longa, ciliata; laminae 10-30 cm longae, 0.5-1.0 cm latae, planae, linearilanceolatae nervo mediano prominulo, longe-acuminatae, ad basin dense pilosae, subtus sparse pilosae pilis longis, supra glabrescentes; inflorescentiae terminales, pedunculis 2-4, ca. 30-40 cm longis; paniculae 15-25 cm longae; racemi 2-3, divergentes, ca. 10-20 cm longi, axilla dense molliter pilosa, interdum pilis longioribus adspersis; rhachis 0.3-0.4 mm lata, viridescens, glabra vel scabrida, flexuosa, in 25 mm 10-11 spiculis praedita; spiculae 3.2-3.3 mm longae, 0.7-0.8 mm latae, lineari-lanceolatae, obtusae; gluma et lemma sterile aequalia, 5-7-nervia, nervis prominulis ad apicem productis, inter nervos adpresse et sparse pilosa; pedicellus brevissimus; flosculus 2.0-2.1 mm longus, albidus, obtusus, ad apicem dense breviter molliterque pilosus.

Species Description - Erect or spreading perennial, leafy throughout, the foliage lax; culms 75-90 cm tall, 1-2 mm thick, terete or slightly compressed, often reddish or purplish; nodes 1-2, 1-3 mm long, appressed-pilose, often glabrescent; sheaths 10-35 cm long, the upper ones longest, 1-3 mm wide, not keeled, sometimes remote from the culm, glabrous or ciliate toward the summit, shorter than the internodes, some reduced to cataphylls 1-3 cm long; ligule 0.3-0.4 mm long, ciliate, the crown often longer than the base; collar hairy on either side, the wedge-shaped area distinct; blades 10-30 cm long, 5-10 mm wide, broadest at the middle, flat, acuminate, the midnerve prominent, the margins scabrous, long-ciliate at the base, densely hairy on the under surface, glabrescent above with a few long hairs just above the ligule, the base equal to the width of the sheath or slightly broader; inflorescence terminal; peduncles 2-4, 15-25 cm long, usually red-tinged; panicles 15-25 cm long; racemes 2-3, widely divergent, 10-20 cm long, the axils densely short-hairy with a few to several long hairs often intermixed; rachis 9.3-0.4 mm wide, greenish, glabrous or scabrous, flexuous, sharply triquetrous; spikelets 10-11 per 25 mm, 3.2-3.3 mm long, 0.7-0.8 mm wide, linear-lanceolate, obtuse, the pedicels 0-0.2 mm long; glume and sterile lemma equal, 5-7-nerved, the nerves meeting at the apex, sparsely pilose between the nerves; fertile floret 2-2.1 mm long, pale yellow or white, obtuse, with a tuft of short crowded hairs at the apex.

Discussion:

TYPE: frequent, Danto Paso, wet banks along rocks, Danta Falls, Rio Cuao, Rio Orinoco, Terr Amazonas, Venezuela, alt. 150 m, November 20, 1948, Bassett Maguire & Louis Politi 27349; U. S. National Herbarium No. 2,040,168.