MIDDLESEX FLORA. 57 



C. altissimus, Willd., var. discolor, Gray. (Cirsium discolor, 

 Spreng., Man.) 

 Maldeu (F. S. Collins). Scarce. Aug.-Sept. 



C. muticus, Pursh. (Cirsium muticum, Michx., Man.) Swamp 

 Thistle. 

 Not very common, Aug.-Sept. 



C. pumilus, Ton-. (Cirsium pumilura, Spreng., Man.) Pasture 

 Thistle. 

 Common ; a white flowereil form occasional. .Tuly-Aug. 



C. horridulus, Pursh. (Cir.sium horridulum, Michx., Man.) Yel- 

 low Thistle. 



Medford and Everett (F. S. Collins). Rather scarce, and found 

 only near salt water. June-July. 



€. ARVENSis, Hoflm. (Cirsium arvense, Scop., Man,) Canada This- 

 tle. 



Very common ; a white flowered form not uncommon. July-Sept. 

 Nat. from Eu. 



Onopordon, Vaill. 



O. ACANTHIUM, L. COTTON THISTLE. 



Watertown (Wm. Boott) ; Tewksbury (C. J. Sprague) ; Chelms- 

 ford (Dr. C. W. Swan) ; Somerville (C. E. Perkins) ; Concord 

 (Minot Pratt). Rare. July. Nat. from Eu. 



Arctium, L. 



A. Lappa, L., var. majus, Gray. (Lappa officinalis. All., var. major, 



Man.) Larger Burdock. 



Westford, near woollen mill (Dr. C. W. Swan) ; Maiden (F. S. 



Collins). Aug.-Sept. Adv. from Eu. 

 A. Lappa, L., var. tomeMosum, Gray. 



Cambridge, waste-heap (Rev. Thos. Morong). Adv. from Eu. 

 A. Lappa, L., var. minus, Gray. Burdock. 



Veiy common ; a form with white flowers occasional ; also a form 



with laciniate leaves. Nat. from Eu. 



Lamps ana, Tourn. 



L. communis, L. Nipplewort. 

 Medford (C. E. Perkins) ; Newton (C. J. Sprague). Nat. from Eu. 



CiCilORiUM, Tourn. 



C. iNTTBus, L. Succory. Chicory. 

 Common, especially near Boston. July-Sept. Nat. from Eu. 



Krigia, Schreb. 



K. Virginica, Willd. Dwarf Dandelion. 

 Common. May-June. 



