48 



CYPERACEAE. 



2. Scirpus americanus Pers. 

 Three-square. Chair-maker's 

 Rush. (Fig. 71.) Perennial by 

 long rootstocks; culms sharply tri- 

 angular, erect, stiff, l°-3*° tall. 

 Leaves 1-3, narrowly linear, keeled, 

 shorter than the culm ; spikelets ob- 

 long-ovoid, acute, 4"-6" long, capi- 

 tate in clusters of 1-7, appearing 

 as if lateral; involucral leaf slender, 

 l'-4' long; scales broadly ovate, 

 brown, often emarginate or sharply 

 2-cleft at the apex, the midvein ex- 

 tended into a subulate awn some- 

 times 1" long, the margins scarious; 

 bristles 2-6, downwardly barbed, 

 shorter than or equalling the achene; 

 stamens 3; achene obovate, plano- 

 convex, smooth, dark brown, mucro- 

 nate. 



Marsh near Whale Bay, 1914. 



Native. Continental North America. 



Flowers in summer. 

 3. Scirpus validus Vahl. Ameri- 

 can Great Bulrush. Mat-rush. . (Fig. 

 72.) Perennial by rootstocks; culm 

 stout, terete, smooth, erect, 3°-9° tall, 

 sometimes f in diameter, sheathed be- 

 low. Involucral leaf solitary, erect, 

 shorter than the umbel ; umbel com- 

 pound, appearing lateral, its primary 

 rays V-4:' long; bracts linear-lanceolate; 

 spikelets becoming oblong-cylindric, ses- 

 sile or some of them peduncled, in capi- 

 tate clusters of 1-5, 2i"-8" long, l*"-2" 

 in diameter; scales ovate or oblong, with 

 a strong midvein which is sometimes ex- 

 current; bristles 4-6, downwardly barbed, 

 equalling or longer than the achene; 

 stamens 3 ; style 2-cleft ; achene plano- 

 convex, obovate, gray, abruptly mucro- 

 nate, dull. [S. lacustris of Reade, Le- 

 froy, Hemsley, Harshberger and H. B. 

 Small.] 



Frequent in marshes. Native. Con- 

 tinental temperate and tropical America ; 

 West Indies. 



4. FIMBRISTYUS Vahl. 

 Annual or perennial sedges. Culms leafy below. Spikelets umbellate or 

 capitate, terete, several- to many-flowered, subtended by a 1-many-leaved in- 

 volucre, their scales spirally imbricated all around, mostly deciduous, all fertile. 

 Perianth none. Stamens 1-3. Style 2-3-cleft, pubescent or glabrous, its base 

 much enlarged, falling away from the summit of the achene at maturity. 

 Achene lenticular, biconvex, or 3-angled, reticulated, cancellate, or longitudi- 

 nally ribbed or striate in our species. [Greek, in allusion to the fringed style 

 of some species.] Some 125 species, widely distributed in temperate and 

 tropical regions. Type species: Fimhristylis acuminata Vahl. 



