42 



CYPERACEAE. 



anatropous, erect. Style 2-3-cleft or rarely simple or minutely 2-toothed. 

 Fruit a lenticular, plano-convex, or trigonous achene. Endosperm mealy. 

 Embryo minute. 



About 65 genera and 3000 species, of very wide geographic distribu- 

 tion. The achenes of many species are transported by birds, and most of 

 the native sedges have probably reached Bermuda by them or by winds. 



Achene not enclosed in a perigynium. 

 Scales of the spikelets 2-ranked. 



Splkelets with several or many perfect flowers. 

 Spikelets with but one perfect flower. 

 Scales of the spikelets spirally imbricated. 



Spikelets with several or many perfect flowers. 

 Style wholly deciduous. 

 Perianth-bristles 4-6. 

 Perianth-bristles none. 



Base of the style persistent as a tubercle on the achene. 

 Spikelets capitate, involucrate ; culm leafy. 

 Spikelet only 1, naked ; leaves mere basal sheaths. 

 Spikelets only 1-4-flowered, some of the flowers imperfect. 

 Style, or its base, persistent as a tubercle on the achene. 

 Style wholly deciduous. 

 Achene enclosed in a perigynium. 



1. Cyperus. 



2. KylUnga. 



3. Scirpus. 



4. FimttrisiitUs. 



5. Dichromena. 



6. Eleocharis. 



7. Rynchospora. 



8. Marlscus. 



9. Carex. 



1. CYPERUS [Tourn.] L. 



Annual or perennial sedges. Culms in our species simple, triangular, leafy 

 near the base, and with 1 or more leaves at the summit forming an involucre to 

 the simple or compound, umbellate or capitate inflorescence. Bays of the umbel 

 sheathed at the base, usually very unequal, one or more of the heads or spikes 

 commonly sessile. Spikelets flat or subterete, the scales readily falling away 

 from the rachis as they mature, or persistent and the spikelets falling away 

 from the axis of the head or spike with most of the scales attached. Scales 

 concave, conduplicate or keeled, 2-ranked, all flower-bearing or the lower ones 

 empty. Flowers perfect. Perianth none. Stamens 1-3. Style 2-3-cleft, de- 

 ciduous from the summit of the achene. [Ancient Greek name for these 

 sedges.] About 600 species, of wide distribution in tropical and temperate 

 regions. Type species: Cyperus esculentus L. 



Style 2-cleft ; achene lenticular ; annuals. 

 Scales obtuse ; achene ovate-orbicular. 

 Scales acute ; achene oblong. 

 Style 3-cJeft ; achene trigonous. 



Spikelets falling away from the axis of the spike, the lower 



pair of scales persistent. 

 Annual ; spikelets nearly terete. 

 Perennials ; spikelets flattened. 



Spikelets \" wide, greenish brown. 

 Spikelets \"-\\" wide, chestnut brown. 



Scales falling away from the persistent rachis of the flat- 

 tened spikelets. 

 Basal leaves elongated ; spikelets spicate. 



Spikelets purple brown ; achene linear-oblong. 

 Spikelets straw color : achene obovoid. 

 Basal leaves reduced to sheaths : spikelets digitate. 



1. C. flavescens. 



2. C. panicitlatits. 



3. C. speciosus. 



4. C. globulosits. 



5. C. bruiincus. 



6. C. rotundus. 



7. C. esculentus. 



8. C. alternifolius. 



