24 



POACEAE. 



2. Cenchrus echinatus L. Southern Bur- 

 grass. (Fig. 32.) Culms finally prostrate and 

 rooting at the nodes, branched; leaf -sheaths 

 loose; blades 4'-16' long, 2i"-8" wide, smooth 

 or rough, flat: spikes 1^-5' long, finally more 

 or less exserted; involucres 20-50, densely 

 crowded, containing 4—6 spikelets, glabrous, 

 green to purplish, pubescent, villous at the 

 base, the spines l^"-2" long, the bristles at the 

 base numerous, slender, distinctly barbed for 

 their whole length; spikelets 3"-3i" long, ex- 

 serted from the involucre. 



Common as a weed in cultivated and waste 

 grounds. Native. Southeastern United States and 

 tropical America. Its burs perhaps brougiit to 

 Bermuda by attachment to migratory birds. Flow- 

 ers from spring to autumn. 



11. STENOTAPHRUM Trin. 



Perennial creeping branched grasses, with rather stout flattened culms 

 and short linear leaves. Spikelets spicate or panicled, acute, mostly '2-flowered, 

 imbedded in depressions on one side of the flattened rachis; scales 4; first 

 scale small or minute, second about as long as the spikelet, third similar to the 

 second, subtending a staminate flower, fourth rigid, enclosing a perfect flower. 

 Stigmas plumose. [Greek, a narrow depression.] A few species of tropical 

 and subtropical distribution, the following typical. 



1. Stenotaphrum secunditum (Walt.) Kuntze. 

 Crab-grass. (Fig. 33.) Widely creeping, some- 

 times 15° long, glabrous, rooting at the lower nodes. 

 Leaf-sheaths keeled, flattened, the blades linear, 

 lY-6' long, 2"-5" wide, blunt and rounded at the 

 apex; spikelets about 3" long. [Iscliaemum secun- 

 datum Walt.; S. americanum Schrank; S. dimid- 

 iatum of A. H. Moore; S. glahrum Trin.] 



In nearly all dry or moist situations. Native. 

 Southeastern United States and tropical America. 

 Flowers nearly throughout the year. Its seeds per- 

 haps transported to Bermuda by migratory birds. 

 One of the best grasses for forming lawns in warm 

 and tropical climates. 



Zizania aquatica L., the Wild Eice of north- 

 eastern North America, is recorded by Eeade as 

 once found by him in marshes north of Hamilton, 

 but it has not been seen in Bermuda by recent 

 collectors and probably would not long exist. 



Library 



