568 CYPERACEJ^ (SEDGE FAMILY.) 



1. PSILOCARYA, Torr. Spikes ovate, terete, the numerous scales all alike 

 and regularly imbricated ; a perfect flower under each : stamens mostly 2 : style 

 2-clefl ; its base or the greater part of it enlarging and hardening to form the beak 

 of the lenticular or tumid more or less cross-wrinkled achenium : bristles wholly 

 wanting (whence the name). 



1. R. SCirpoides. Annual, 4' -10' high; leaves flat; spikes in broad 

 and open cymes, 20 - 30-flowered ; scales oblong-ovate, acute, chestnut-colored; 

 achenium obscurely wrinkled, beaked with the sword-shaped almost wholly per- 

 sistent style, and somewhat margined. (Psilocarya scirpoides, Torr. & Ed. 2.) 

 Inundated places, Rhode Island and Plymouth, Massachusetts. 



(R. NITENS (Scirpus nitens, Vahl. Psilocarya rhynchosporoides, Torr.), like 

 this, but with a more wrinkled and short-beaked achenium, takes its place in 

 Southern States.) 



2. EURHYNCH6SPORA. Spikes terete or biconvex, few -many-flowered; 

 some of the lower scales almost always empty : stamens mostly 3 : style conspicu- 

 ously 2-cleft, its base only forming the tubercle or beak of the mostly lenticular 

 achenium : bristles of the perianth usually present, and merely rough or barbed- 

 denticulate (not plumose}. 

 * Achenium transversely wrinkled: bristles mostly 6, upwardly denticulate. 



2. R. cym6sa, Nutt. Culm triangular; leaves linear ('wide); cymes 

 corymbose ; the spikes crowded and clustered ; achenium round-obovate, twice the 

 length of the bristles, four times the length of the depressed-conical tubercle. 

 Low grounds, Penn. and New Jersey to Virginia, and southward. 



3. R. Torreyana, Gray. Culm nearly terete, slender ; leaves bristle-form ; 

 cymes panicled, somewhat loose, the spikes mostly pedicelled; achenium oblong- 

 obovate, longer than the bristles, thrice the length of the broad compressed- 

 conical tubercle. Swamps ; pine barrens of New Jersey, and southward. 



4. R. inexpansa, Vahl. Culm triangular, slender ; leaves narrowly linear ; 

 spikes spindle-shaped, mostly pedicelled, in drooping panicles ; achenium oblong, half 

 the length of the slender bristles, twice the length of the triangular-subulate 

 tubercle. Low grounds, Virginia and southward. 



* # Achenium smooth and even. 

 - Bristles of the perianth 6, long and conspicuous, upwardly denticulate. 



5. R. f&sca, Roam. & Schultes. Leaves bristle- form, channelled; spikes 

 ovate-oblong, few, clustered in 1 - 3 loose heads (dark chestnut-color) ; achenium 

 obovate, half the length of the bristles, equalling the triangular-sword-shaped acute 

 tubercle, which is rough-serrulate on the margins. Low grounds, New Jersey 

 to Maine and Lake Superior : rare. Culm 6'- 12' high. (Eu.) 



6. R. graci!6nta, Gray. Leaves narrowly linear; spikes ovoid, in 2 - 4 

 small clusters, the lateral long-ped uncled ; achenium ovoid, rather shorter than the 

 bristles, about the length of the flat awl-shaped tubercle. Low grounds, S. 

 New York, New Jersey, and southward. Culm very slender, l-2 high. 



*- - Bristles none or 1 - 3 and minute : spikes pale, 1 -flowered. 



7. R. pallida, M. A. Curtis. Culm (l-2 high) acutely triangular; 

 leaves and spikes as in the next species, but only a- terminal dense cluster, 

 which is less white or turns pale reddish-tawny ; achenium obovate-lenticular, 



