MIDDLESEX FLORA. 



A. laevigata, Poir. Smooth Eock-Ckess. 

 Melrose and Medford (F. S. Collins) ; Pine Hill, Medford, 1885 

 (Dr. C. W. Swan); Woburn (Wm. Boott). Not common. May- 

 June. 



A. Canadensis, L. Sickle-Pod. 

 Medford, Chelmsford, Acton, et al. Not common. 



A. perfoliata. Lam. Tower Mustaed. 

 Maiden and West Medford (Wm. Boott) ; Billerica (Dr. C. W. 

 Swan). Eare. June-July. 



A. confinis, Wats. (A. Drummondli, Gray; Man.) 



Dracut (Dr. C. W. Swan) ; Concord (Walter Deane). Bare. June 

 July. 



Bakbabea, E. Br. 



B. VULGARIS, E. Br. Yellow Eocket. Wintee Cress. 

 Common. The forms kuown as var. stricta, Eegel, Somerville 

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

 ARCUATA, Koch, Lowell (Dr. C. W. Swan). May-June. Thor- 

 oughly established, but probably naturalized from Eu. 



Erysimum, L. 



E. cheiranthoides, L. Worm-Seed Mustard. 

 Medford, 1866 (Wm. Boott) ; Maiden (F. S. Collins) ; along rail- 

 road, Lowell ; near woollen mills, Westf ord (Dr. C. W. Swan) ; 

 occasional along the B. & A. E. E., Ashland (Eev. Thos. Morong). 

 Jime-July. 



E. repandum, L. 



Westford, woollen-mill yard, a few plants, 1884 and 1885 (Dr. C. 

 W. Swan). July. Adv. from Eu. 



"Stem5-10in. high. Leaves lanceolate, acuminate, crenateorrepand- 

 dentate, or entire, recurved at the tip, somewhat rough-hairy. 

 Flowers yellow, pedicels half the length of the calyx. Pods obtusely 

 four-angled, nearly terete, scarcely larger than the horizontally 

 patent pedicel." Wagner, Deutsche Flora. 



Sisymbrium, L. 



S. officinale, Scop. Hedge Mustard. 



Common. June-Sept. Nat. from Eu. 

 B. Sophia, L. 



Chelmsford, abundant on a small patch of waste ground in 1884, 



wholly gone in 1885 (Dr. C. W. Swan). June. Adv. from Eu. 

 S. Pannonicum^ Jacq. 



Westford, woollen-mill yard ; Tewksbury, roadside, a few plants in 



a limited area (Dr. C. W. Swan). June-July, 



