CYPERACEAE 39 



absent, except in the bottom spikelet, but sometimes present in all the 

 spikelets. Otherwise as in Ehjmus. 



1. H. elymoides Mackenzie & Bush, nom. nov. Culms 2°-l° hi^h : 

 spikes 3'-6' lonj^, more or lessexserted : spikelets 4''''-5''' long : awn often 

 12^' long : glumes glabrous to hairy. — Frequent in rocky woods. June- 

 July. {Elymits Hystrix L. ; Hystrix Hystrix (L. ) Millsp. ) 



Family 14. CYPERACEAE J. St. llil. 

 Grass or rush-like herbs with usually solid-triangular culms (some- 

 times terete or flattened). Flowers arranged in spikelets, one in the 

 axil of each scale. Perianth none or composed of bristles or scales. 

 Stamens one to three. Ovary one-celled, containing a single erect anat- 

 ropous ovule. Style 2-3-cleft. Fruit a 3-sided or lenticular achene. 

 Embryos minute at the base of the mealy endosperm. A difficult family, 

 for the study of which ripe fruiting specimens are essential. 



Flowers all, or at least some of them, perfect. 



Scales of the spikelet strictly two-ranked. 



Spikelets in a terminal inflorescence. 



Spikelets with two or more perfect flowers, 

 Spikelets with but one perfect flower. 

 Inflorescence axillary. 

 Scales of spikelets imbricated all around. 

 Base of style swollen and bulbous. 

 Bristles (perianth) present. 

 Bristles not present. 



Base of style persistent. 

 Base of style not persistent. 

 Base of style not swollen and bulbous. 

 Perianth bristles present. 

 Broad inner scales absent. 

 Broad inner scales present. 

 Perianth bristles absent, but a 

 hyaline scale present. 

 Flowers all monoecious or dioecious. 

 Achene naked and bony. 

 Achene enclosed in a sac (perigynium). 



1. CYPERUS L. 



Culms triangular, bearing the spikelets in a terminal compound or 

 single cluster or head, subtended by one or more leaves which form an 

 involucre. Spikelets flattened, the scales two-ranked and keeled. Flow- 

 ers perfect and perianth none. Style 2- or 3-cleft and achene lenticular 

 or triangular. 



Achene lenticular ; style 2-cleft. 



Styles much exserted. 1. C. diandrus. 



Styles scarcely exserted. 2. C. rivularis. 



Achene triangular ; style o-cleft. 



Scales tips recurved or recurved-awned. 



Scales tipped with a recurved awn. 3. C. i-nflexun. 



Scale tips merely recurved. 4. C. acuminatus. 



