122 MIDDLESEX FLORA. 



P. virgatum, L. 



Concord (E. S. Hoar) ; and common near salt water. 



P. latifolium, L. 



Not uncommon. 



P. clandestinum, L. 



Townseud, Lowell, Medford, Concord, et al. Not uucoramon. 

 P. viscidum, Ell. 



Arlington, Aug. 31, 1881 (C. E. Perkins). 

 P. scoparium, Lam. (P. pauciflorum. Ell., Man.) 



Chelmsford (Dr. C. W. Swan) ; Reading (C. E. Perkins) ; Wal- 



tham, abundant (Walter Deane) ; Wakefield (F. S. Collins). 

 P. dichotomum, L. 



Dr. C. W. Swan, who has made a special study of this perplexing 



species (or group of species), has kindly contributed the result of 



his investigations of the county forms. 

 "The following are the principal forms found witliin the county 



limits, some of them being considered distinct species : 



a. Low, tufted, spreading, slender, geniculate, branching, hairy, 

 with small, simple little-stalkedorpartlysheathed panicles, and small 

 diflfuse spikelets. (P. dichotomum, L., P. nodiflorum, Lam.) Common. 



b. Similar but taller, more upright, less branclied; panicles more 

 stalked. Forms of a., and approaching c. and/. Common. 



c. Slender, tufted, light green, growing in woods, with spreading, 

 narrow, tapering leaves, nearly straight culms, simple short-stalked 

 panicles, and small scattered spikelets; nearly smooth, but the 

 lower nodes sometimes anuularJy bearded. Not uncommon. 



d. Densely tufted, hairy, with straight culms, numerous narrow 

 erect leaves, small panicles, with sheathed stalks and small scattered 

 spikelets. Wilmington and Maiden (F. S. Collins). Also at 

 Gloucester. 



e. Largei-, hairy, witli wider, more spreading? leaves and larger pani- 

 cles, growing iu rich soil. Wilmington (F. S. Collins.) 



/. Tall, erect, little tufted, stoutish or sometimes rather slender, 

 smooth, with spreading or ascending leaves, long-stalked panicles 

 numerously flowered, the spikelets larger, about a line in length, 

 obovate, elliptical, and extending well down upon the rather virgate 

 branches. Not infrequent iu ratlier moist soil. 



g. A well marked, stoutish, thick-leaved form of f, with nodes 

 strongly and conspicuously bearded, but otherwise smootli, lias 

 not been reported from tlie county, but should be looked for. 

 Specimens have been received from Nantucket and New Jersey. 



h. A large form of /, with largest leaves 4i inches by 5 lines.. 

 In moist soil at Wilmington (Dr. C. W. Swan). 



