ERIOPHORUM HEMICARPHA 333 



tile scales; perianth-bristles 6-many, white or brown, 1-3 cm. long, stamens 

 1-3, style 3-cleft achene 3-angled; leaves linear, stems triangular to round; 

 bog-perennial from a rootstock. 



1. Bristles 2.5-3 cm. long; achenes obovate; bracts 



ovate to lance-ovate ; involucral leaves 2-4 E. polystdchyum 



2. Bristles 1.5-2.5 cm. long; achenes linear-oblong; 



involucral leaf usually only 1 E.grdcile 



HELEOCHARIS Robert Brown 1810 SPIKE RUSH 



(Gr. helos, marsh, charis, grace, from the habitat) 



PL 44, fig. 18. 



Spikelets solitary, terminal, without an involucre ; flowers perfect, with 

 concave, spirally imbricated scales ; perianth-bristles usually 1-12, stamens 

 2-3, style 2-3-cleft, achenes lens-shaped or 3-angled, base of the style form- 

 ing a swollen tip to the achene; leaves reduced to basal sheaths; stems 

 simple, round, angular, flattened or grooved ; annual or perennial. 



1. Style 2-cleft ; achenes lens-shaped or bi-convex 



a. Perennial from horizontal rootstocks 



(1) Stems 1-4 in. high; upper sheath papery H.olivdcea 



(2) Stems .5-5 ft. high; upper sheath not 



papery H. palustris 



b. Annuals with fibrous roots 



( 1 ) Achenes black with a low tiny tubercle H. atropurpurea 



(2) Achenes brown, the large ovoid tubercle 



y^ its length H. ovdta 



2. Style 3-cleft ; achenes 3-angled or swollen 



a. Stems 2-6 in. high; achenes ribbed and net- 



like H. aciculdris 



b. Stems 8-15 in. high 



(1) Bristles 2-4 or wanting, shorter than the 



achene ; achenes roughened H. tennis 



(2) Bristles 4-8, longer than the achene; 



achenes smooth H.rostelldta 



HEMICARPHA Nees 1834 

 (Gr. hemi, half, karphos, chaff, from the single inner scale or sepal) 



Spikelets solitary or in heads, terminal with an involucre of 1-3 leaves ; 

 flowers perfect, scales spirally imbricated ; perianth a single sepal, bristles 

 none, stamens 1-3, style 2-cleft '; leaves and stems thread-like; tufted annual 

 sedge. 

 Stems 1-5 in. high ; spikelets 1-4, 2-3 mm. long H. micrdntha 



