THISTLE FAMILY 949 



1. S. Fremontii A. Gray. Stem 1 dm. high or less, branched from the base, 

 shghtly floccose; leaves spatulate or Unear-cuneate, often 3-lobed at the summit, 

 8-15 mm. long, floccose; involucres about 6 mm. high; bracts .5, broadly oblong; 

 ligules 5, golden veUow, 4 mm. long and fullv half as wide. Desert plains: Ariz. 

 — Utah— Xev.— Cahf. L. Son. Ap-:\Iy. 



105. TETRANEURIS Greene. 



Perennial (aU ours) or annual, caulescent or scapose, more or less villous or 

 silky herbs. Leaves usually entire, rarely some of them lobed, alternate, either 

 clustered at the base, or scattered along the stem, or both. Heads radiate, 

 rarelj' discoid, on slender peduncles. Involucre hemispheric, or nearly so; bracts 

 several in two subequal series; receptacle convex, naked. Raj'-flowers 10-20, 

 pistillate and fertile; ligules yellow, oblong, broad, 3- (rarely 4-) toothed; nerves 

 4. Disk-flowers many, hermaphiodite and fertile; coroUas with 5 short pubescent 

 teeth. Anther-tips broad, triangular or ovate. Style-branches dilated, trun- 

 cate, somewhat penicillate at the tips. Achenes obpyramidal, 5-angled, about 

 3 times as long as broad, densely hirsute. Pappus of about 5 hj-aline squamellae, 

 with a strong midrib, which sometimes is produced into an awn. 



Heads sessile among the leaves. 1. T. depressa. 



Heads distinctly pedimcled. 



Stems scapiform, leafy only at the base. 

 Leaves appressed-silky. 



Leaves not strongly 3-nerved on the broadened bases. 



Leaves spatulate or oblanceolate, 2-4 cm. long; scape stout, 5-10 cm. high. 



2. T. septentrionalis. 

 Leaves linear or linear-oblanceolate ; scape 10-20 cm. high. 



Leaves silvery-silkj- ; hgules 6--8 mm. long. .3. T. acaulis. 



Leaves greenish, sparingly silky; Ugules 8-10 mm . long. 



4. T. simplex. 

 Leaves strongly 3-nerved on the broadened bases, narrowly linear-oblanceo- 

 late. 5. T. trinervala. 

 Leaves loosely ^-illou-s or glabrate. 



Leaves, scape, and involucre decidedly villous. 



Involucre more than 1 cm. broad; scape 3-8 cm. long; plant densely cespi- 

 tose-pul^inate ; leaves not conspicuously broad-based. 



6. T. lanigera. 

 In%'olucre less than 1 cm. broad: scape 1-3 cm., (rarely 3-5 cm.) long; 



plant loosely cespitose; leaves conspicuoiisly broad-based. 



7. T. brerifolia. 

 Leaves glabrous or sparingly ^'illo^^s; scape finely pubescent or \t11ous (long- 



^tHous only in T. Torreyana). 

 Branches of the caudex decidedly villous at the ends, with long, at first 

 white, but later brownish hairs. 

 Pappus-scales lanceolate, acuminate, not awned; scape villous. 



8. T. Torreyana. 

 Pappus-scales oval, awned; scape silkj'. 



Bracts oval. 9. T. arizonica. 



Bracts hnear-oblong. 10. T. Crandallii. 



Branches of the caudex not conspicuously villous. 



Bases of the leaves not wider than the oblanceolate or almost linear 

 blades; branches of the caudex short and stout. 

 Leaves glabrous, scarcely punctate; bracts shghtly shorter than the 



disk ; Ugules not strongly nerved. 11. T. epunctata. 



Leaves long-hairy, distinctly punctate; bracts three-fourths as long 

 as the disk; hgules strongly nerved. 12. T. angustifolia. 



Bases of the leaves 2—1 times as mde as the linear leaf-blades; branches 

 of the caudex or rootstock elongate. 13. T. fastigiata. 



Stems 2-3 dm. high, with 2-6 stem-leaves. 



Basal leaves oblanceolate to Unear-oblanceolate, more than 5 mm. wide; invo- 

 lucre hemispheric. 14. T. leptoclada. 

 Basal leaves narrowly linear-oblanceolate, less than 5 mm. wide: involucre nar- 

 rower. 15. T. Ivesiana. 



1. T. depressa (T. & G.) Greene. Puhdnate-cespitose perennial; leaves 

 narrowly linear or nearly so, 1-2 cm. long, 1-2 mm. wide, glabrate, hairj'-tufted 

 at the base; heads sessile; involucres about 6 mm. high and 8 mm. broad; bracts 

 oblong, obtuse; achenes silky-strigose ; pappus-squamellae ovate, tapering into 

 an a^Ti. Acdnella depressa T. & G. Dry hills and mountains: Utah. 



2. T. septentrionalis Rydb. Leaves mosth- rounded at the apex, 5-8 mm. 

 wide, canescent-tomentose, subvelutinous; scape 5-10 dm. high, rather thick, 



