Genus 34. 



GRASS FAMILY. 



2. Muhlenbergia palustris Scribn. Swamp Drop- 

 seed. Fig. 440. 



M. palustris Scribn. Bull. U. S. Dep. Agr. Agrost. 11 : 47. 

 1898. 



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



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

 glabrous; blades erect, 1-2' long, about 1" wide, smooth 

 beneath and rough above; panicle slender, contracted, 

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

 of the awn, \\"-i\" long, the first scale about I as long 

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

 flowering scale about ii" 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, 1 J"— 3" wide, those of 

 the branches i'-j,' long, about 1" wide; panicle 3' -6' 

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

 scales about J" 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 filiformis 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'-z' long, erect 

 or appressed; spikelets ii"-ii" 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. 



