Bamboo growing in isolated clumps of as many as 10 culms each; culms to ca 8 cm diam and 10 m long, erect to arching, often leaning on other vegetation; culm sheaths triangular when flattened, acute at apex, ca 25 cm long, densely ferruginous-pubescent on outer surface; branches glabrous, long and spreading, heavily armed at nodes with spines mostly 8-25 mm long. Leaves mostly on outer parts of branches, mostly 1-1.5 cm apart on the stem; leaves on juvenile culms 2.5-4.5 cm apart, the blades to 24 cm long and 4.5 cm wide, the sheaths 4-8 cm long; mature sheaths ca 2.5 cm long, glabrous except usually ciliate along one or both margins, the truncate apex with a stout branched trichome on either side 7-13 mm long; petioles 0.5-2 m long; blades oblong-lanceolate, narrowly acute to acuminate at apex, rounded at base, 3-15 cm long, 10-25 mm wide, glabrous, the margins sparsely and inconspicuously scabrid. Inflorescences not seen. Croat 10101. Rare; known only from near the beginning of Armour Trail and along the stream near Chapman Trail 900. Forming small stands in the forest. Mexico to Colombia and Venezuela. Range in Panama unknown.