CYPERACE/E.* 



CHARLES F. MILLSPAUGH AND AGNES CHASE. 



Grass-like or rush-like herbs. Inflorescence in solitary or clus- 

 tered i -many flowered spikelets; flowers perfect or imperfect, i or 

 rarely 2 in the axil of each glume; scales 2-ranked or spirally imbri- 

 cated. Perianth hypogynous, composed of interior scales or bristles, 

 or wanting. Stamens, 1-3, rarely more. Ovary i-celled, sessile or 

 stipitate, ovule i, anatropous, erect, style 2-3-cleft or minutely 

 2-toothed, rarely simple. Fruit a plano-convex, lenticular, trilateral 

 or subglobose achene: 



Spikelets all alike, fertile flowers perfect (except Cyperus canus): 

 Glumes 2-ranked Cyperus. 



Glumes spirally imbricated: 



Spikelets several to many-fruited: 

 Achene tuberculate: 



Perianth of bristles Heleocharis. 



Perianth none Dichromena. 



Achene not tuberculate: 

 Bilateral, achene sessile: 



Perianth of bristles Scirpus. 



Perianth none Fimbristylis. 



Trilateral, achene stalked Fuirena. 



Spikelets i-2-fruited: 



Achene tuberculate, style 2-fid Rhynchospora. 



Achene not tuberculate, style 3-fid Cladium. 



Spikelets unisexual, achene osseous Scleria. 



CYPERUS L. Sp. PI. 44. 



Including Mariscus and Torulinium. Inflorescence in more or 

 less densely disposed subumbellate spikes. Fertile flowers bisexual 

 (except in C. canus). Rachilla winged or wingless; spikelets few to 

 many-fruited; scales distichous, the lower two empty; bristles none. 

 Stamens 1-3. Style 3-cleft, achene trilateral: 



Rachilla persistent, glumes deciduous: 

 Flowers perfect: 



Spikelets digitate or congested on a reduced rachis: 

 Achene oblong-turbinate, markings of longitudinal / tdnatus 



impressed lines \ ' 



Achene obovoid, hexagonally reticulated ochraceus. 



Achene pyriform with lozenge-shaped reticulations elegans. 

 Spikelets spicate: 



Achene broad-turbinate, reticulated and papillate compressus. 

 Achene oblong, hexagonally reticulated: 

 Reticulations conspicuous, interspaces convex esculentus. 

 Reticulations faint, interspaces concave rotundus. 



Flowers unisexual canus. 



*The cuts present an enlargement of the achene, dorsal view (also lateral view in some 

 cases) magnified 20 diameters, a transverse section at its greatest diameter (the base of the sec- 

 tion being the ventral side), a portion of the surface magnified, showing the markings, and usually 

 beneath this a cross-section of the same, illustrating their prominence. 



6 7 



