CARDUACEAE 1307 
6. Carduus Hélleri Small. Stem 0.6-1 m. tall, simple or sparingly branched above, 
somewhat floccose : leaves relatively few and distant ; blades membranous, narrowly oblong 
or lanceolate in outline, 1-1.5 dm. long, arachnoid above, lanuginose beneath, sinuate- 
pinnatifid, the teeth or segments spine-tipped : heads few, relatively small: involucres 
about 2 cm. high, thinly pubescent, the outer bracts lanceolate, 3-3.5 mm. broad, each 
tipped with a rather weak somewhat spreading spine. 
On plains or prairies, Texas. Spring. 
7. Carduus austrinus Small. Stems 4-11 dm. tall, simple or sparingly branched 
above, rather closely floccose : leaves quite numerous ; blades thickish, narrowly oblong to 
narrowly lanceolate in outline, arachnoid above, rather felty beneath, 1-2-pinnatifid, the 
segments spine-tipped: heads solitary or few, relatively small: involucres about 15 mm. 
high, sparingly pubescent, the outer bracts about 2 mm. broad, each tipped with a spread- 
ing or recurved weak spine. 
In bottom lands, Texas. Spring. 
8. Carduus revolütus Small. Stem 0.5-2 m. tall, simple or sparingly branched 
above, rigid, more or less floccose: leaves conspicuously narrow and often relatively elon- 
gated ; blades leathery, 1-3 dm. long or shorter above, glabrous or essentially so and dark 
green above, closely white-woolly or tomentose beneath, pinnatifid, the teeth or segments 
sometimes remote, each tipped with a rigid spine, entire or spiny-toothed : heads solitary 
or few, relatively small: involucres 20-25 mm. high, somewhat woolly, the outer bracts 
ee mm. broad, each tipped with a weak spreading or recurved spine: achenes 4 mm. 
ong. 
In low pine lands, South Carolina, Georgia and Florida. Summer and fall. 
9. Carduus fláccidus Small. Stem 7-16 dm. tall, sparingly floccose, almost simple 
or sparingly branched above, slender: leaves few, remote, the basal and lower cauline, 1- 
3 dm. long ; blades thin, narrowly oblanceolate or linear-spatulate in outline, 1-2-pinnat- 
ifid, the segments and their teeth spine-tipped, those of the upper cauline leaves nearly 
similar to those of the lower, but usually less deeply pinnatifid, all glabrous or essentially 
so above, thinly gray tomentose-woolly beneath : heads relatively small: involucres about 
1.5 cm. high, sparingly webby, the outer bracts 1.5-2 mm. broad : achenes 3.5-4 mm. long. 
In woods and on dry banks, Georgia to Arkansas and Texas. Spring. 
10. Carduus Nuttallii A. Gray. Stem 1-4 m. tall, early glabrate, winged by the 
decurrent leaf-bases, more or less branched : leaves numerous, evenly and closely distrib- 
uted along the stem ; blades various, those of the basal and lower cauline leaves 1.5-3.5 
dm. long, broadly oblong or oblong-spatulate in outline, 2-pinnatifid, the segments and 
teeth rigidly spine-tipped, those of the upper cauline leaves gradually reduced in size, 
commonly pinnatifid, the segments often rather distant : heads relatively small: involucres 
1.5-2 cm. high, sparingly pubescent, the outer bracts about 2 mm. broad, each terminating 
1n a spine about 1 mm. long : achenes about 4 mm. long. 
In dry soil, coastal plain, South Carolina to Florida and Mississippi. Spring and summer. 
11. Carduus altissimus L. Stem 1-3 m. tall, more or less pubescent, usually much 
branched : leaves numerous, the basal and lower cauline 1.5-3 dm. long ; blades oblong or 
elliptic, or broadest below or above the middle, finely or coarsely toothed, the teeth spine- 
tipped, the upper cauline leaves smaller, mainly oblong-lanceolate, toothed like the lower 
ones, or those on the branches pinnatifid, all sparingly pubescent above, densely white- 
tomentose beneath : heads showy : involucres about 3 cm. high ; the outer bracts 3-4 mm. 
broad, each terminating in a spreading or reflexed spine: achenes 4.5-5 mm. long. 
In fields and thickets, Massachusetts to South Dakota, Florida and Texas. Summer and fall. 
12. Carduus díscolor (Muhl.) Nutt. Similar to C. altissimus in habit, but rarely 
over 2 m. tall: leaf-blades mainly oblong-lanceolate or ovate-lanceolate, 1-2 dm. long, or 
those of the basal and lower cauline leaves longer and those of the branches smaller, all 
quite finely pinnatifid, densely white-tomentose beneath: heads showy: involucres 2.5-3 
em. high, the outer bracts 3-3.5 mm. broad, each with a subulate spreading or reflexed 
tip 4-5 mm. long : achenes 3-4 mm. long. 
In fields and on hillsides, Quebec to South Dakota and Georgia. Summer and fall. 
13. Carduus lanceolàtus L. Stem 1-1.5 mm. tall, rigid, more or less branched, 
winged by the decurrent leaf-bases, pubescent : leaves numerous, often rather crowded ; 
blades 1-2-pinnatifid, the segments and teeth rigidly spine-tipped, those of the basal and 
lower cauline leaves 1-3.5 dm. long, those of the upper cauline smaller, lanceolate in out- 
line, all strigose above, grayish woolly beneath : heads showy: involucre 2.5-3 cm. high, 
