GRAMINEAE. 77 



3. Syntherisma serotina Walt. Late-flowering Finger-grass. (I. F. f. 

 241a.) Culms 2-5 dm. long, tufted, at length much branched and prostrate and 

 rooting at the lower nodes. Sheaths, at least the lower ones, densely papillose- 

 hirsute with spreading hairs; leaves 1.5-10 cm. long, usually less than 5 cm., 

 3-10 mm. wide, lanceolate, pubescent on both surfaces; racemes 2-6, 2.5-10 cm. 

 long; spikelets about 1.5 mm. long and 0.6 mm. wide, elliptic, acute, usually in 

 pairs, the first scale wanting, the second 3 -nerved, the fourth scale white. Low, 

 open grounds, Del. to Fla. and Miss. June-Oct. 



4. Syntherisma linearis (Krock.) Nash. Small Crab-grass. (I. F. f. 

 241.) Culms 2-5 dm. tall, finally prostrate, and forming large mats. Sheaths 

 smooth and glabrous; leaves 1.5— 13 cm. long, 2.5-6 mm. wide, smooth and 

 glabrous on both surfaces; racemes 2-5, 2-8 cm. long, finally widely spreading; 

 spikelets slightly exceeding 2 mm. long and about 1 mm. wide, elliptic, acutish, 

 usually in pairs, the first scale wanting or sometimes present as a mere rudiment, 

 the second scale 3-nerved, the third scale 7-nerved, the fourth scale deep chestnut- 

 brown when mature. Introduced into waste places and fields and along roadsides, 

 N. S. to S. Dak., south to Fla. and Kans. July-Sept. [Panicum g/abrum Gaud.] 



5. Syntherisma sanguinalis (L.) Dulac. Large Crab-grass. (I. F. f. 

 240.) Culms 1 m. or less long, finally prostrate at the base and rooting at the 

 lower nodes. Lower sheaths densely papillose-hirsute; leaves 4-20 cm. long, 4-10 

 mm. wide, more or less papillose-hirsute on both surfaces; racemes 3-10, 5-18 cm. 

 long; spikelets 2.5-3 mm - l° n g an( ^ about 0.8 mm. wide, elliptic-lanceolate, acute, 

 in pairs, the first scale minute, triangular, the second scale 3-nerved, about one-half 

 as long as the spikelet, the third scale 7-nerved, the fourth scale yellowish white, 

 acutely apiculate. Cultivated places, fields, roadsides, etc., throughout N. Am., 

 principally in the north. July-Aug. [Panicum sanguinale L.] 



6. Syntherisma fimbriata (Link) Nash. Fimbriate Crab-grass. Culms 

 8 dm. long or less, finally prostrate at the base and rooting at the lower nodes. 

 Lower sheaths densely papillose-hirsute with spreading hairs; leaves 2-8 cm. 

 long, 5-10 mm. wide, both surfaces glabrous or more or less pubescent ; racemes 

 2-9. 2-12 cm. long; spikelets 3-3.5 mm. long and about 0.8 mm. wide, lanceolate, 

 very acute, in pairs, the first scale minute, the second scale 3-nerved, more than one- 

 half as long as the spikelet, the third scale 7-nerved, the fourth scale lanceolate, 

 very acute, yellowish- white. Dry sandy soil, D. C. to Fla., west to Tex., also in 

 Kans. June-Sept. 



14. BRACHIARIA Ledeb. 



Usually perennial grasses, with flat leaves and a panicle composed of alternate 

 scattered one-sided racemes with the spikelets borne in 2 rows. Spikelets I -flowered, 

 articulated to the pedicel below the empty scales. Scales 4, the outer 3 membran- 

 ous; fourth scale chartaceous, enclosing a palet of similar texture and a perfect 

 flower. Stamens 3. Styles distinct. Stigmas plumose. Grain free. Species 

 about 100, natives of temperate and tropical regions. 



Spikelets ovate, acute, about 2.5 mm. long. 1. B. digitarioides, 



Spikelets oval or obovoid, obtuse, turgid, about 3 mm. long. 2. B. obtusa. 



1. Brachiaria digitarioides (Carpenter) Nash. Narrow Panicum. (I. F. 

 f. 245.) Glabrous, culms erect from a long and stout creeping rootstock, 9-15 dm. 

 tall, simple, stout, smooth. Sheaths smooth; leaves 1-2.5 dm. long, 8-16 mm. wide, 

 long-acuminate; panicle linear, 1.5-3 dm. long, its branches 2.5-7.5 cm. long, 

 erect; spikelets about 2.5 mm. long, ovate, acute; first scale about one-half as long 

 as the spikelet, acute, 3-nerved; second about 2 mm. long, 5 -nerved and a little 

 exceeded by the 3-nerved third one; the fourth 3-nerved, slightly shorter than the 

 third. In water, Del. to Fla. and Tex. July-Aug. {Panicum digitarioides 

 Carpenter.) 



2. Brachiaria obtusa (H. B. K.) Nash. Blunt Panicum. (I. F. f. 246.) 

 Glabrous, culms erect, 3-6 dm. tall, simple or branching at base, smooth. Sheaths 

 smooth; leaves 6.25-22 cm. long, 2-6 mm. wide, usually erect, long-acuminate; 

 panicle linear, 5-15 cm. long; branches 1.8-3.7 cm. long, appressed; spikelets 

 about 3 mm. long, crowded, oval or obovoid, obtuse, turgid; first scale shorter 



