CYPERACEAE. 43 



35. AETHROSTYLlblUM Rupr. in Mem. Acad. St. Petersb. VI. 5=^: 117. 1839. 



Woody, mostly vine-like grasses, the leaves usually borne on short branches 

 whorled at the nodes, the leaf-blades linear or lanceolate, jointed with the 

 sheaths. Spikelets racemose, usually appearing only after long intervals, some- 

 times only after many years. Spikelets linear, few-several-flowered, stalked 

 or nearly sessile, more or less secund, articulated above the lower 3 or 4 empty 

 scales; lowest scale small, the others similar to ea^h other, acute or acumi- 

 nate, many-nerved, not awned; palets narrow, 2-carinate, scarcely shorter than 

 the scales. Flowers perfect. Stamens 3. Ovary glabrous; styles 2. Grain 

 oblong. [Greek, referring to the jointed spikelets.] About 20 species, natives 

 of tropical America. Type species: ArtJirostylidium Haenlei Rupr. 



1. Arthrostylidium capillifolium Griseb. Mem. Am. Acad. II. 8: .531. 1862. 



Glabrous; stem slender, wiry, woody, climbing over shrubs and small trees, 

 sometimes 5 m. long, often forming large colonies. Branches numerous, 

 fascicled at the nodes, short; leaves capillary, flexible, 5-15 cm. long; spike- 

 lets few, at the ends of the branches, lanceolate, 8-12 mm. long, 2-3 mm. 

 wide, several-flowered. 



In low dense coppices and pinelands, Andros, New Providence, Cat Island, 

 Great Exuma : — Cuba ; I'orto Rico. Old Man's Beard. 



Family 2. CYPERACEAE J. St. Hil. 



Sedge Family. 



Grass-like or rush-like herbs. Stems (culms) slender, solid (rarely 

 hollow), triangular, quadrangular, terete or flattened. Roots fibrous (many 

 species perennial by long rootstocks). Leaves narrow, with closed sheaths. 

 Flowers perfect or imperfect, arranged in spikelets, one (rarely 2) in the 

 axil of each scale (glume, bract), the spikelets solitary or clustered, 1- 

 manj^-flowered. Scales 2-ranked or spirally imbricated, persistent or de- 

 ciduous. Perianth liypogynous, composed of bristles, or interior scales, 

 rarely calyx-like, or entirely wanting. Stamens 1-3, rarely more. Fila- 

 ments slender or filiform. Anthers 2-celled. Ovary 1-celled. Ovule 1, 

 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 6o genera and 3000 speices, of very wide geog- 

 raphic distribution. 



Fertile flowers perfect. 



Basal empty scales of the spikelet none, or not more than two. 



Scales of the spikelets distichous ; bristles none. 1. Ci/pcrus. 



Scales of the spikelets spirally imbricated (apparently 

 distichous in AhUdgaurdia). 

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

 Spikelet 1 ; perianth-bristles usually present ; culms 



leafless. 2. FAcocharis. 



Spikelets usually several or numerous ; bristles none ; 



culms leafy below. 3. Stcnophi/Uus. 



Style wholly deciduous: no tubercle on the achene. 

 Base of the stvle swollen ; bristles none. 



Spikelets nearly terete, not flattened. 4. Fiinhristuli.f. 



Spikelets distinctly flattened. 5. Abilduuaidia. 



Base of the style not swollen ; bristles usually 



present. ' <*• Scirpus. 



Basal empty scales of the spikelets 3 or more. 



Style 2-cleft, its base persistent as a tubercle on the 

 achene. 

 Bristles none: culm monocephalous. t- Dtclirotncna. 



Bristles usually present ; culm usually polycephalous. 8. Rynchospora. 



