110 COMMON CANADIAN WILD PLANTS. 



and not spreading. Stem very tall, and smoothish, and 

 sparingly leafy. Heads single or few. Swamps and low 

 woods. 



4. C. arvensis, Hoff. (Oirsium arvense, Scop.) (CANADA 

 THISTLE.) Scales of the involucre with reflexed points. 

 Leaves prickly, smooth both sides, or slightly woolly 

 beneath. Roots extensively creeping. Heads small and 

 numerous. Fields and roadsides. 



2. CAR'DUUS, Tourn. PLUMELESS THISTLE. 



1. C. nu'tans, L. (MusK .THISTLE.) Leaves decurrent, 

 sinuate, spiny. Heads solitary, drooping. Flowers purple. 

 Atl. Prov. 



3. OSfOPOR'DON, Vaill. SCOTCH THISTLE. 



0. Aean'thium, L. A coarse branching herb, 2-4 feet 

 high, with woolly stem and leaves. Bristles of the pappus 

 united at the base into a ring. Roadsides and old fields ; 

 not common. 



4. ARC'TIUM, L. BURDOCK. 



A. Lapp a, L. (Lappa officinalis, AIL, var. major. Gray.) 

 A coarse plant with very large cordate petioled leaves, and 

 numerous small globular heads of purple flowers. The in- 

 volucre forms a bur which clings to one's clothing, or to the 

 hair of animals. Near dwellings, mostly in manured soil. 

 Varies somewhat as to size and pubescence of the heads. 



5. CENTAIIRE'A, L. STAR-THISTLE. 



1. C. Cy'anus, L. (BLUE-BOTTLE.) An old garden plant, 

 found occasionally along roadsides. False raysi- very large. 

 Scales of the involucre fringed. Leaves linear, entire or 

 nearly so. Stem erect. Heads single at the ends of the 

 branches, the flowers bluish. Pappus very short. 



2. C. ni'gpa, L. (KNAPWEED.) No* false toys. Scales 

 of the globular involucre black-fringed. Leaves lanceolate, 

 mostly entire, rough. Flowers purple. Pappus short or 

 none. Waste places, chiefly eastward. 



