484 



COMPOSITAE. 



[Vol.. III. 



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

 Not nearly as common as the next species in the Middle States. Naturalized frrm Europe. Other 

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

 Beggar's Buttons. July-Oct. 



3. Arctium minus Schk. Common 

 Burdock. (Fig. 4057.) 



Arctium w/?^'Schk. Bot. Handb. 3: 49. 1803. 

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

 Arctium Lappa var. minus A. Gray, Syn. Fl. I: Part 

 2, 397. 1884. 



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. Anthers 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 these plants.] 



Besides the following, some 



About 250 species, widely distributed in the northern hemisphere. 

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



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

 f 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. 1. C. lanceolatus. 



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. altissimus. 



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



Heads naked-peduncled, 1' high: involucral bracts thin. 4. C. Virginianus 



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

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



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. 



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



Outer bracts with spines of nearly or quite their length. 8. 



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



3. Leaves green both sides, somewhat pubescent beneath. 

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



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



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

 Heads large, few, 1/-4' broad; flowers all perfect and fertile. 



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

 Heads peduncled, naked, or with 1 or 2 bracts at the base; flowers purple. 13. C. muticus. 

 Heads small, numerous, 1' or less broad; flowers imperfect, dioecious. 14. C. arvensis. 



Sf ~ 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. 



C. inidulatus. 

 C. Piatt ensis. 

 C. ochrocentrus. 

 C. Nebraskensis. 



C. odoratus. 

 C. Hillii. 



