484 



COMPOSITAE. 



[Vol,. III. 



L'tf^cMXtW: 



In waste places, New Brunswick and Ontario to f outliern New York, and locally in the interior. 

 Not nearly as common as the next species in the Middle Slates. Naturalized frtm Europe. Other 

 names are Cockle-bur, Cockle-button, Cuckold-dock, Hurrbur, Stick-button, Hardock, Bardane, 

 Beggar's Buttons. July-Oct. 



3. Arctium minus Schk. Common 

 Burdock. (Fig. 4057.) 



Arclium ff/j««i.Schk. Bot. Handb. 3: 49. 1803. 



Lappa minor DC. Fl. Fran. 4: 77. 1805. 



Arclium Lappa var. minus A. Gray, Syn. Fl. i: Part 



2, 397. KS84. 



Smaller than the preceding species, seldom over 

 5° high. Leaves similar, the lower deeply cordate; 

 petioles hollow, not deeply furrowed; heads num- 

 erous, racemose on the branches, short-peduncled 

 or sessile, 6"-9" broad; bracts of the involucre 

 glabrous or slightly cottony; the spines of the outer 

 ones spreading, those of the inner erect and shorter 

 than the flowers; corolla-tube about as long as the 

 limb. 



In waste places, common throughout our area. 

 Naturalized from Europe. Called also Cuckoo Button. 

 Leaves rarely laciniate or pinnatifid. July-Nov. 



97. CARDUUS L. Sp. PI. 820. 1753. 



Erect, branching or simple, prickly herbs, some species acaulescent, with alternate or 

 basal, sinuate-dentate lobed or pinnatifid, usually very spiny leaves, sometimes decurrent, and 

 large many-flowered, solitary or clustered, discoid heads of purple, yellow or white, tubular, 

 perfect and fertile, or rarely dioecious flowers. Involucre ovoid or globose, its bracts prickle- 

 tipped or unarmed, imbricated in many series. Receptacle flat or convex, bristly. Corolla- 

 tube slender, the limb deeply 5-cleft. Filaments pilose, or rarely glabrous, .\nthers sagit- 

 tate at the base. Style-branches short or elongated, obtuse. Achenes obovate or oblong, 

 compressed or obtusely 4-angled, glabrous, smooth or ribbed. Pappus of several series of 

 slender, plumose, minutely serrulate, or simple bristles, connate at the base. [The ancient 

 Latin name of tliese plants.] 



About 250 species, widely distributed in the northern hemisphere. Besides the following, some 

 35 others occur in the southern and western parts of North America. 



■K- Pappus-bristles, at least those of the inner flowers, plumose. (Plumed Thistles.) 

 t Outer involucral bracts, or all of them, strongly prickly-pointed. 

 1. Leaves glabrous or hispid above, tomentose beneath. 

 All the bracts of the involucre tipped with prickles; naturalized weed. i. C. lanceolalus. 



Outer bracts prickle-tipped, the inner merely acuminate; native species. 

 Branches leafy up to the heads; involucral bracts firm or rigid. 



Leaves undivided, lobed or dentate, rarely pinnatifid. 2. C. allissimus. 



Leaves deeply pinnatifid into lanceolate or linear segments. 3. C. discolor. 



Heads naked-peduncled, i' high: involucral bracts thin. 4. C. firginianus. 



2. Leaves tomentose on both sides, or becoming glabrous above; western. 

 Leaves pinnately parted; segments linear, entire or lobed. 5. C. Pilcheri. 



Leaves pinnatifid into triangular or lanceolate dentate segments. 

 Outer bracts with spines less than one-half their length. 



Leaf-lobes triangular; flowers pink or purple. 6. C. undulalus. 



Leaf-lobes linear-lanceolate to oblong; flowers cream-color. 7. C. Plaltensis. 



Outer bracts with spines of nearly or quite their length. S. C. ochrocenlrus. 



Leaves entire or undulate; outer pappus-bristles barbellate. 9. C. Nebraskensis. 



3. Leaves green both sides, somewhat pubescent beneath. 

 Leaf-lobes acute; bracts of the involucre faintly nerved. 10. C. odoralus. 



Leaf-lobes blunt; bracts with prominent glutinous midnerve. 11. C. Hillii. 



t t Bracts of the involucre not at all prickly-pointed, or scarcely so. 

 Heads large, few, i'-4' broad; flowers all perfect and fertile. 



Heads involucrate by the upper very spiny leaves; flowers usuallj- yellow. 12. C. spinosissimus. 

 Heads peduncled, naked, or with i or 2 bracts at the base; flowers purple. 13. C. mulicus. 

 Heads small, numerous, i' or less broad; flowers imperfect, dioecious. 14. C. arvensis. 



■Jf- -:v Pappus-bristles simple, or minutely serrulate. ^ Plumeless Thistles.) 



Head solitary, nodding; bracts of the involucre lanceolate. 15. C. nutans. 



Heads clustered, erector ascending; bracts linear. 16. C. crispus. 



