50 



CYPEKACEAE. 



Common in marshes. Native. Southeastern United States and West In- 

 dies. Flowers from spring to autumn. 



6. ELEOCHARIS E. Br. 



Annual or perennial sedges. Culms simple, triangular, quadrangular, 

 terete, flattened or grooved, the leaves reduced to sheaths or the lowest very 

 rarely blade-bearing. Spikelets solitary, terminal, erect, several-many-flowered, 

 not subtended by an involucre. Scales concave, spirally imbricated all around. 

 Perianths of 1-12 bristles, usually retrorsely barbed, wanting in some species. 

 Stamens 2-3. Style 2-cleft and achene lenticular or biconvex, or 3-cleft and 

 achene 3 -angled, but sometimes with very obtuse angles and appearing turgid. 

 Base of the style persistent on the summit of the achene, forming a terminal 

 tubercle. [Greek, referring to the growth of most of the species in marshy 

 ground.] About 140 species, widely distributed. Type species: Scirpus palus- 

 tris L. 



Spikelet little thicker than the stout culm ; scales coriaceous. 



Culm nodose-septate. 1. E. interstincta. 



Culm continuous. 2. E. cellulosa. 



Spikelet much thicker than the slender culm ; scales not cori- 

 aceous. 

 Style 2-cleft : achene lenticular ; annuals. 



Upper sheath truncate, 1 -toothed. 3. E. capitata. 



Sheath membranous, hyaline. 4. E. praticvla. 



Style 3-cleft ; achene trigonous ; perennials. 



Achene smooth. 5. E. bermudiana. 



Achene finely reticulated. 6. E. rostellata. 



1. Eleocharis interstincta 



(Vahl) E. & S. KNOTTED SPIKE- 

 RUSH. (Fig. 75.) Perennial by 

 stout rootstoeks; culms terete, 

 hollow, nodose, papillose, 3 tall 

 or less, the sterile ones sharp- 

 pointed. Sheaths membranous, 

 the lower sometimes bearing 

 short blades; spikelet terete, 

 cylindric, many-flowered, sub- 

 acute, l'-lf long, 2" in diam- 

 eter, not thicker than the culm ; 

 scales ovate, orbicular or obo- 

 vate, obtuse or the upper acute, 

 narrowly scarious-margined, 

 faintly many-nerved, persistent; 

 bristles about 6, rigid, retrorsely 

 barbed, as long as the body of 

 the achene or shorter; stamens 

 3 ; style 3-cleft, exserted ; achene 

 obovoid, brown, shining, with 

 minute transverse ridges, con- 

 vex on one side, very obtusely 



angled on the other, 2 or 3 times as long as the conic acute black broad-based 

 tubercle. [Scirpus interstinctus Vahl; E. equisteoides Torr. ; Scirpus plan- 

 tagineus of Lefroy and of Hemsley; apparently mistaken for Equisetum 

 palustre by Lefroy and by H. B. Small.] 



Frequent in marshes. Native. Eastern United States ; West Indies ; tropical 

 continental America. Flowers in summer and autumn. 



