HITCHCOCK AND CHASE—GRASSES OF THE WEST INDIES. 397 
107. ARTHROSTYLIDIUM Rupr.’ 
Spikelets few-flowered, in racemes, the lower 1 or 2 lemmas empty, the 
rachilla articulate between the florets (rarely below the glumes). In Cuba the 
species are called “ tibisf” as are those of Lasiacis.? 
Blades subcapillary, 1 to 3 mm. wide, as much as 30 em, long, drying involute. 
1. A. capillifolivm. 
Blades not subcapillary, flat. . 
Tips of culms and branches retrorse-scabrous. 
Blades about 6 mm. wide________---- 5 8. A. haitiense. 
Blades 10 to 12 mm. wide_____________-_-_ 9. A. multispicatum, 
Tips of culms and branches not retrorse-scabrous. 
Blades not over 5 cm. long, usually shorter (rarely 6 cm. long in young 
shoots). 
Sheaths not bristly ; inflorescence racemose.___2. A. sarmentosum. 
Sheaths conspicuously squarrose-bristly at the summit; inflo- 
rescence elongate, consisting of distant groups of spikelets. 
3. A. distichum. 
Blades or some of them at least 8 cm. long; inflorescence racemose. 
Sheaths not bristly at the summit, or with but one or two weak 
bristles. 
Blades pubescent beneath, thick, rigid, the midnerve and mar- 
gins prominent __--_---___________________ 6. A. urbanii. 
Blades glabrous. 
Spikelets crowded, terminating the densely whorled leafy 
branches ; blades acuminate_________ 5. A. prestoei. 
Spikelets not crowded, borne on solitary or fascicled axil- 
lary branchlets; blades obtuse at tip. 
13. A. obtusatum. 
Sheaths bristly at the summit. 
Bristles 1 to 2 cm. long, some of them squarrose or reflexed, not 
curled and tangled at the tips________ 4, A. fimbriatum. 
Bristles less than 5 mm. long, erect, the tips curled and 
tangled. 
Blades pubescent beneath __-_-_________ 7. A. pubescens. 
Blades glabrous. 
Spikelets divergent on a zigzag axis, the flowering 
branches axillary ____________ 10. A. excelsum. 
Spikelets erect or appressed, the axis not zigzag. 
Inflorescence of slender racemes, leafless or nearly 
$0__--_-_-_---- 11. A. cubense. 
Inflorescence of narrow panicles, terminating leafy 
. branches __________ 12. A. angustifolium. 
1. Arthrostylidium capillifolium Griseb, Mem. Amer. Acad. nb. ser. 8: 531. 1862. 
Arundinaria capillifolia Hack. Oesterr. Bot. Zeitschr. 53: 69. 1903. 
*In the tribe Bamboseae the genera are here accepted as distinguished by 
Hackel (Engl. & Prantl, Pflanzenfam. 27: 1887). Further field study and col- 
lections of flowering plants are necessary before the true generic characters of 
this tribe can be understood. 
7In this and other genera of bamboos the description of habit is necessarily 
omitted in those species not observed by the authors and not adequately 
described from living plants. 
