1186 CARDUACEAE 
2. Sideranthus phyllocéphalus (DC.) Small. Stems pubescent, 1-4 dm. tall, 
branched at the base and often diffuse : leaf-blades 2-8 cm. long, those of the cauline leaves 
pinnatifid, the segments tipped with bristle-like teeth : heads showy, solitary and sessile at 
the ends of the leafy branches: involucres 6-9 mm. high, the outer bracts more or less 
foliaceous : ray-flowers with narrow ligules 8-11 mm. long. 
On sandy beaches, Texas and adjacent Mexico. Summer and fall. 
3. Sideranthus rubiginósus (T. & G.) Britton. Stems viscid and pubescent, 2-9 
dm. tall, branching: leaf-blades oblong to lanceolate, 3-5 cm. long, remotely dentate with 
awn-tipped teeth, mostly sessile: heads terminating naked peduncles, corymbose : involucres 
campanulate, 7-9 mm. high ; bracts lanceolate to linear, acuminate, with green spreading 
tips, glandular without: ray flowers with oblong or slightly oblanceolate ligules 6-7 mm. 
long. 
On plains and prairies, Nebraska and Colorado, south to Texas. Fall. 
4. Sideranthus aüreus (A. Gray) Small. Stem thinly lanuginous and glandular, 
1-2.5 dm. tall, branched at the base, the branches sometimes decumbent : leaves rather 
few ; blades linear or slightly linear-spatulate, 1-2.5 em. long, pinnatifid, dentate at least 
near the base : involucres campanulate, about 1 cm. high ; bracts linear to linear-oblong, 
glandular, blunt, the outer with green tips, the inner almost scarious : ray-flowers 18-25; 
ligules barely 1 cm. long, golden yellow: achenes turbinate, with 10-12 stout pappus 
bristles. [Aplopappus aureus A. Gray. ] 
On prairies, Houston, Texas. Summer. 
5. Sideranthus glabérrimus Rydb. Stems more or less branched from the woody 
base, the branches mostly ascending, 1-4 dm. long, corymbose above, glabrous or merely a 
little puberulent, but wholly destitute of woolly pubescence: leaf-blades pinnatifid or 
ponscur parted, the segments usually entire, acute: involucres about 5 mm. high; 
racts linear-lanceolate to linear, glabrous or essentially so, most of them terminating in 
pale subulate tips: ray-flowers with ligules 4-7 mm. long. 
In dry soil, South Dakota to Wyoming and the Indian Territory. Spring to fall. 
6. Sideranthus Cótula Small. Similar to S. glaberrimus in habit. Stems and 
branches copiously glandular-pubescent : leaf-blades 1-2 cm. long, finely bipinnatifid, the 
segments mostly less than 1 mm. wide : involucres 4-5 mm. high ; bracts glandular-pubes- 
cent, acute or acuminate : ray-flowers with narrow ligules 4-6 mm. long. 
In dry soil, the Indian Territory. Summer. 
7. Sideranthus Machaeránthera Small. Stems clustered on a woody base, about 1.5 
dm. tall, sparingly corymbose above, finely glandular-pubescent : leaf-blades much larger 
and ‘coarser than those of S. Cotula, 2.5-4.5 cm. long: involucres 5-6 mm. high ; bracts 
minutely glandular, acuminate : ray-flowers with ligules 6-9 mm. long. 
In dry soil, along the Brazos River, Texas. Summer. 
8. Sideranthus australis (Greene) Rydb. Stems branched at the woody base, the 
branches 1-4 dm. tall, mostly ascending, thinly pale-canescent, sparingly branched above : 
leaf-blades 1-2.5 cm. long, coarsely toothed or pinnatifid, the teeth or segments slenderly 
spine-tipped : involucres 5-6 mm. high; bracts more or less subulate-tipped, pubescent : 
ray-flowers with ligules about 1 cm. long. 
In dry or rocky soil, Texas to New Mexico and adjacent Mexico. Spring to fall. 
9. Sideranthus spinulósus (Pursh) Sweet. Stems woolly-canescent, 1-3 dm. tall, 
commonly branched: leaf-blades 1-3 cm. long, pinnately parted, the segments mostly 
toothed or pinnatifid : involucres 8-9 mm. high ; bracts appressed, oblong-lanceolate to 
linear, acute : ray-flowers with oblong ligules 5-6 mm. long. 
On plains, Northwest Territory to North Dakota, Texas, Arizona and Mexico. Summer and fall. 
31. ISOCOMA Greene. 
Herbaceous or woody plants, often with viscid foliage. Leaves alternate: blades en- 
tire toothed or pinnately parted. Heads radiate, solitary or clustered. Involucres mainly 
campanulate, several- to many-flowered: bracts leathery or firmer, obtuse or merely acute 
-zat the more or less thickened tip, imbricated. Receptacle pitted. Ray-flowers usually 
several, pistillate. Disk-flowers more numerous than the rays, perfect. Corollas yellow, the 
throat much inflated. Stigmas somewhat flattened and slightly broadened upward, hairy 
at the tip. Achenes broadened upward, silky. Pappus of numerous slender barbellulate 
bristles. 
$ : y $ ; 1. I. Drummondii. 
Leaf-blades entire or nearly so: bracts of the involucres acute or acutish. 2. T. coronopifolia. 
Leaf-blades pinnately parted : braets of the involucres obtuse. 
