92 Karl M. Wiegand and Arthur J. Eames 



19. CYPERACEAE (Sedge Family) 5 



a. Spikelets umbellate, in umbellate clusters, or solitary. 



b. Scales of the spikelet 2-ranked; perianth bristles none. 1. Cyperus 



b. Scales of the spikelet in several ranks, spirally arranged. 

 c. Base of style bulbous, persistent as a tubercle, jointed with the achene or at 

 least differing abruptly in texture. 

 d. Perianth bristles present; spikelet solitary. 3. Eleocharis 



d. Perianth bristles wanting; spikelets umbellate. 4. Stenophyllus 



c. Base of style not as above; spikelets umbellate or solitary. 

 d. Base of style bulbous, deciduous ; bristles none ; plant low, with irregularly 



subumbellate spikelets. 5. Fimbristylis 



d. Base of style not forming a distinct tubercle which is articulated with the 

 achene, persistent ; plant various. 

 e. Perianth bristles 0-8, exserted or included in fruit. 6. Scirpus 

 e. Perianth bristles many, much exserted in fruit. 7. Eriophorum 



a. Spikelets or spikes arranged in spikes or racemes or in racemose clusters, or rarely 

 in a single terminal irregular cluster, rarely solitary but when so the achene in- 

 closed in a sac. 

 b. Scales of the spikelet 2-ranked. 2. Dulichium 



b. Scales of the spikelet or spike several-ranked, spirally arranged. 

 c. Achenes naked. 

 d. Achenes not conspicuously bony or ivory-like, not raised on a disk; fertile 

 flowers perfect. 

 e. Style 2-cleft; perianth bristles usually present; achene with a beak-like 

 tubercle. 8. Rynchospora 



c. Style 3-cleft ; perianth bristles wanting ; achene without a tubercle. 



9. Mariscus 

 d. Achenes bony or ivory-like, often raised on a disk; flowers monoecious. 



10. Scleria 

 c. Achenes inclosed in a sac (perigynium), which is often inflated; flowers 

 monoecious or rarely dioecious. 11. Carex 



1. Cyperus (Tourn.) L. 



a. Spikelets 1.5-3 mm. in diam., flat; style 2-cleft; achenes lenticular. 



b. Scales membranous, dull ; style branches exserted 2.3-4 mm. ; stamens 2. 



1. C. diandrns 



b. Scales subcoriaceous, lustrous ; style branches exserted 1.5 mm. ; stamens 3. 



2. C. rividaris 

 a. Spikelets not more than 1.4 mm. in diam. ; style 3-cleft ; achenes triangular. 



b. Scales with recurved tips ; plants annual. 3. C. aristatus 



b. Scales with straight tips. 

 c. Spikelets in distinct umbellate spikes, stramineous or castaneous. 

 d. Scales 3.2-4 mm. long, strongly overlapping and appressed, stramineous ; 

 axis narrowly winged; achenes linear-oblong, acute; culms with perennial 

 bulbous bases. 

 e. Nearly all the spikelets 9-20 mm. long. 4. C. strigosus 



c. Nearly all the spikelets 4-8 mm. long. 4a. C. strigosus, 



var. compositus 

 d. Scales 2-2.5 mm. long (see also 3d d). 



e. Scales thin, brownish, strongly nerved, deciduous ; spikelets somewhat 

 flattened, acute or obtuse, not subulate-tipped; rhachis narrowly winged, 

 not thickened ; achenes oblong-obovoid, obtuse ; plants perennial, with 

 slender tuber-bearing rootstocks. 5. C. esculentus 



6 Dates under each species in this family refer to the fruiting period. 



