68 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



Rachilla falling away from the axis, slightly winged: 

 Achene equilateral or nearly so: 



Facets convex, angles round-margined echinatus. 



Facets concave, angles sharp ligularis. 



Achene dorsally compressed bruneus. 



Rachilla breaking up in i-fruited nodes, the broad \ 

 wings clasping the achene: \ 



Achene much compressed dorsally, 1.4 mm. long Michauxianus. 



Achene little compressed, 1.8 mm. or more: 



Facets all concave, reticulations pitted lentiginosus : 



Dorsal facets plane, ventral concave, reticulations / 

 papillate. y 



\EUCYPERUS. Spikelets compressed; rachilla persistent on the 

 axis, glumes deciduous. 



Cyperus uncinatus Poir. in Lam. Encyc. 7:247. 



Bracts 34, leaf-like, 2-10 cm. long. Inflorescence a 2-5-rayed 

 umbel, i spike sessile (inflorescence sometimes reduced to the single 

 sessile spike), rays .54.5 cm. long. Spikes russet to chestnut, dense 

 flabellate, 1-1.7 cm - wide, composed of 6-25 

 spikelets divergent from the reduced rachis. 

 Spikelets compressed, oblong, 4-5x6-12 mm., 

 5-16 fruited, rachilla wingless. Glumes less 

 than twice the length of the achene, naviculate, 

 ovate-oblong, abruptly tapering into a squarrose 

 smooth awn ^ its own length, prominently 9-11- 

 nerved. Stamen (in our specimens) i, lateral, 

 ( " Staminibus J-i," Clarke in Urb. Symb. 2:24.) 



Style longer than the achene, divided ^ its length. Achene dull 

 black, oblong-turbinate, .4-. 5x1.1 mm., in section triangular, ventral 

 facet plane, dorsal facets slightly concave, marked by wavy longitu- 

 dinal impressed lines including single rows of circular pits with 

 prominent lips. 



Hab. Mangrove swamp, Sisal, and near Merida, Schott, sine 

 num., Ceranas, Merida, Sept. 15, 1864, 77, Sisal, Nov. 9, 1865, go8a\ 

 Cerro de Maxcaan, Sept. 14, 1865, 

 910; "6 to 10 inches high, com- 

 mon in old fields, Oct.," Izamal, 

 Gaumer fO2j (Cyperus squarrosus 

 Field Col. Mus. Bot. 1:354), San 

 Anselmo 24.26. 



The plant is called X-CHAB- 

 XAN, "Like a woman's greased 

 hair," by the Mayas. 



Cyperus cauus Presl. in Rel. 



Haenk. 1:170. 



Bracts 12-15, leaf-like, 20-30 

 dm. long. Inflorescence an open, 

 many-rayed corymbose umbel; 

 rays slender, 6-12 cm. long; 

 corymbs 4-8 cm. in diameter, 



bractlets ovate, .5-1 cm. Spikes of 2-6 spikelets, digitate from the 

 reduced rachis. Spikelets dioecious, compressed, 2-3x10-15 mm., 



