MIDDLESEX FLORA. 59 



Cfcetida, L. 

 Westford, woollen-mill yard (Dr. C. W. Swan). Adv. from Eu. 

 "Stem erect, leafy, branching, hairy; leaves hairy, runcinate- 

 pinnatitid, the uppermost lanceolate, deeply incised at the base; 

 peduncles drooping before flowering; beaks of the marginal 

 achenia shorter than the involncre, those of the interior longer ; the 

 entire involucre downy and villous; hairs simple and glandular; 

 bracts of the involucre lanceolate, acute." Koch, Syn. Fl. Germ. 



Prenantiiks, Vaill. 

 P. alba, Ti. (Nabalus albus, Hook., Man.) White Lettuce. 



Common. Ang.-Sept. 

 P. altissima, L. (N'abalus altissimns, Hook., Man.) Tall White 



Lettlci:. 



CommDii. Aug. -Sept. 

 P. serpentarla, Pursli. (NabaUis Fraseri, DC, Man.) LlON'S 



Foot. Uall-of-the-eakth. 



Tewksbury and Winehestcr (Dr. V,. VV. Swan) ; Belmont and 



Arlingron (C. E. Perkins); Medtonl (\Vm. P.ontr) ; WalthamList; 



Concord (Minot Pi'att). Not conn no n. Aug.-Scpt. 



'J'akaxacdm, Hall. 

 T. officinale, Weber. (T. Dens-leoni^, Desf., Man.) Dandelion. 

 Very common. Apr.-July. 



LactuCA, Tourn. 



L. Canadensis, L. Wild Lettuce. 



Common. Aug.-Scpt. 

 L. integrifolia, Bigel. (L. Canad-nsis, var, in'egrifolia, Torr. & 



Gr.iy, Man.) 



Tewksbury (Dr. C.W. Swan) ; Maiden and Melrose (F. S. Collins). 



Not very common. Aug. -Sept. 

 L. hirsuta, Muhl. (L. Canailensis, var. sanguinea, Torr. & Gray, 



Man.) 



Lowell (Dr. C. W. Swan) ; M:ilden, Melrose, et al., not rare (F. S. 



Collins). Aug.-Sept. 

 L. SCARiOLA, L. Prickly Lkituck. 



Maiden (F. 8. Ct>llins) ; Soinerville (C. E. Perkins); Cambridge 



(Wm. Boott). Not connnon. Aug. Nat. from Vln. 

 L. leucophaea. Gray. (Mulgedium leucophamin, DC, Man.) 



Blue Lettuce. 



Widely distributed; not uiicominon. Aug.-Sept. 



SoNCii us, L. 

 S. oleraceus, L. Sow- thistle. 



Malilen, Somerville, Westford, Framingham, et al. Not uncommon. 

 Nat. from Eu. 



