MIDDLESEX FLORA. 37 



M. tenellum, Bigel. 

 Cambridge and Tewksbury (Bigelow's Fl. Bost.) ; Natick (Austin 

 Baoon) ; Silver Lake and Mystic Pond (Wm. Boott) ; Groton and 

 Westford (Dr. C. W. Swan). July-Aug. 



Proseepinaca, L. 



P. palustris, L. Mermaid Weed. 

 Common. June-July. 



Trapa, L. 



T. NATAJSfs, L. Water Chestnut. 

 Medford and Maiden (F. S. Collins) ; Concprd EiVer (C. W. Jenks). 

 Introduced from Europe, and, in the last locality, apparently 

 naturalized. 



" Eootstock furnished at the joints with tufts of roots, each tuft 

 forming a pyramidal plume; leaves floating, about 14 in. broad, 

 rhomboidal, thickish and nerved, bimucronately toothed, subpub- 

 esceot at the nerves beneath ; petiole 2-3 times longer, distended 

 below blade into an oblong intumescence, filled with cellular pith, 

 and acting as a buoy ; flowers small, ■^hite, submersed, pellucid ; 

 peduncles 1-flowered, axillary." Bot. Eeg., Vol. 1. 



ONAGRACE/E. EVENING -PRIMROSE FAMILY. 



Circ^a, Tourn. 

 C. Lutetiana, L- Enchanter's Nightshade. 



Common. June-July. 

 C. alpina, L. 



Generally distributed, but not so common as the preceding. Jxily. 



Epilobium, L. 



E. angustifolium, L. (E. spicatum, Lam.) Great Willow- 

 Herb. 

 Very common. July-Aug. 



E. palustre, L., var. lineare, Gray. 

 Common. Aug.-Sept. 



E. coloratum, Muhl. 

 Common. July-Sept. 



OENOTHERA, L. 



CE. biennis, L. Evening Primrose. 



Very common. June-Sept. 

 CE. biennis, L., var. muricata, Lindl. 



Cambridge (F. S. Collins). 



