56 MIDDLESEX FLOKA. 



*S. viscosus, Li. 

 Lowell, waste ground (Dr. F. Nickerson) ; Aug.-Oct. Adv. from Eu. 

 "Coarser thau the preceding, vlseld-pubescent, strong-scented; 

 leaves once or twice piimatifld ; heads rather larger, more peduncu- 

 late; involucre sparingly and slenderly braoteolate at base, its 

 bracts not black-tipped; rays with inconspicuous ligule; akenes 

 glabrous." Syn. P'l. N. A. 



S. aureus, L. Golden Ragwort. 

 Common. May-June. 



S. aureus, L., var. obovatus, Torr. & Gray, Melrose (F. S. 

 Collins). 



S. aureus, L., var. Balsamitae, Torr. & Gray, Stoneham; 

 (Blgelow's Fl. Bost.) ; Woburn (C. E. Perkins). 



Centaurea, L. 



C. Cyamis, L. Bachelor's Button. Bluebottle. 

 Escaped from gardens. July-Aug. Int. from Eu. 



C. nigra, L. Knapweed. 



Chelmsford (Dr. C. W. Swan) ; Acton (L. L. Dame) ; Billerica (C. 

 W. Jenks) ; and common for many years in the towns near Boston. 

 Forms with white and pink flowers not uncommon ; occasional 

 forms with marginal flowers much enlarged. Aug. -Sept. Nat. 

 from Eu. 



C. Jacea, L. 

 Spreading in a field in E. Lexington (Miss Eliza Wellington) . Adv. 

 from Eu. 



" Heads usually larger (than nigra) ; brownish appendages of the 

 Involucral bracts merely lacerate; marginal flowers neutral and with 

 enlarged palmate corollas, forming conspicuous false rays ; other- 

 wise like nigra." Syn. Fl. N. A. 



C. leucophcea, Jord. 

 What may be this species was collected at Westford, near the 

 woollen mills, by Dr. C. W. Swan. The plants are about a foot 

 high, with numerous pinnatifid radical leaves, and stem leaves 

 similar but smaller and less divided, the uppermost short and linear. 

 The heads are about the size of those of C. nigra, rose color, the 

 scales of the involucre conspicuou'-ly veined, with darker, ciiiate tips. 



C. benedicta, L. (Cnicus benedictus, L., Man.) Blessed Thistle. 

 Cambridge, waste-heap, a few plants, 1885 (Kev. Thos. Morong; 

 specimen in herb. of). Adv. from Eu. 



Cnicus, Tourn., L. 



C. LANCEOLATUS, Hoffm. (Cirsium lanceolatiuu, Scop., Man.) Com- 

 mon Thistle. 

 Common. July-Sept. Nat. from Eu. 



