GENUS 34. 



GRASS FAMILY. 



2. Muhlenbergia palustris Scribn. Swamp Drop- 

 seed. Fig. 440. 



M. palustris Scribn. Bull. U. S. Dep. Agr. Agrost. n : 47. 

 1898. 



M. Schreberi palustris Scribn. Rhodora, 9: 17. 1907. 



Culms slender, weak, 2-3 long; sheaths smooth and 

 glabrous; blades erect, i'-2' long, about i" wide, smooth 

 beneath and rough above; panicle slender, contracted, 

 4'-6' long, its branches appressed; spikelets, exclusive 

 of the awn, ii"-i$" long, the first scale about % as long 

 as the second which is i as long as the spikelet, the 

 flowering scale about \\" long, shortly 2-toothed at the 

 apex, and bearing an awn between the teeth 3-4 times 

 its length, the callus hairy. 



In swampy ground, District of Columbia and Illinois. 

 Sept. 



3. Muhlenbergia sobolifera (Muhl.) Trin. Rock Dropseed. Fig. 441. 



Agrostis sobolifera Muhl.: Willd. Enum. 95. 1809. 

 Muhlenbergia sobolifera Trin. Unifl. 189. 1824. 



Glabrous, culms 2-3 tall, erect, slender, simple, 

 or sparingly branched above, smooth. Sheaths 

 smooth, those of the culm shorter than the inter- 

 nodes, those of the branches overlapping and 

 crowded ; ligule very short, truncate ; blades rough, 

 those of the culm 4'-6' long, ii"-3" wide, those of 

 the branches i'~3' long, about i" wide; panicle 3' -6' 

 in length, slender, its branches f'-i' long; outer 

 scales about i" long, half to two-thirds the length 

 of the spikelet, equal, or the lower somewhat shorter, 

 acute, scabrous, especially on the keel ; third scale 

 scabrous, obtuse, 3-nerved, the middle nerve usually 

 excurrent as a short point. 



Rocky woods, New Hampshire to Minnesota, south to 

 Virginia, Tennessee and the Indian Territory. Sept.- 

 Oct. 



4. Muhlenbergia mexicana (L.) Trin. Satin-grass. Wood-grass. Fig. 442. 



Agrostis mexicana L. Mant. 1:31. 1767. 

 Agrostis filifortnis Willd. Enum. 95. 1809. 

 Muhlenbergia mexicana Trin. Unifl. 189. 1824. 

 M. foliosa Trin. Gram. Unifl. 190. 1824. 



Glabrous, culms 2-4 long, erect, or often prostrate, 

 much branched, smooth. Sheaths shorter than the' 

 internodes, excepting at the extremities of the branches, 

 where they are crowded and overlapping, smooth or 

 scabrous ; blades scabrous, those of the culm 4'-6' long, 

 i "-3" wide, the branch leaves smaller ; panicle 2' -6' 

 long, contracted, its branches spike-like, i'-2' long, erect 

 or appressed; spikelets ii"-ij" long; outer scales some- 

 what unequal, exceeding the flowering one, or slightly 

 shorter, acuminate or short-awned, scabrous especially 

 on the keel ; third scale acuminate, scabrous, particu- 

 larly toward the apex. 



In swamps and borders of fields, New Brunswick to 

 Wyoming, south to North Carolina and Texas. Knot-root 

 grass. Aug-Sept. 



