THISTLE FAMILY 239 



Veins of the leaves pubescent below; heads 4-5 mm. high; panicle with long 

 branches. 16. S. salebrosa. 



Stem more or less pubescent. 



Heads 5 mm. or more high; leaves pubescent. 17. S. polyphylla. 



Heads about 4 mm. high; plant comparatively slender. 



Leaves pubescent, at least on the veins. 18. S. canadensis. 



Leaves glabrous, except the scabrous-cillolate margins. 



19. S. serra. 

 Leaves densely canescent, especially beneath. 

 Leaves usually broadly lanceolate. 



Leaves scabrous above. 20. S. dumetorum. 



Leaves softly puberulent on both sides. 21. S. pruinosa. 



Leaves linear-lanceolate, finely and rather softly canescent on both sides, more or 

 less yellowish gray. 22. S. gilvocanescens . 



VI. Radulae. 



One species. 23. S. Garretlii. 



VII. INCANAB. 



Plant low, 1-2 dm. high; inflorescence corymbiform; branches not secund. 



Bracts oval to oblong, obtuse. 24. S. nana. 



Bracts lanceolate, acute. 25. S.'nivea. 



Plants taU, 2-6 dm. high; inflorescence narrow, or if open with distinctly secund branches. 

 Bracts oblong or linear, obtuse; stem-leaves scarcely triple-veined; inflorescence 

 usually narrow. 

 Stem-leaves oblanceolate. 26, iS. pulcherrima. 



Stem-leaves spatulate or broadly oblanceolate. 27. S. radulina. 



Bracts lanceolate or ovate, acute; stem-leaves distinctly triple- veined; inflorescence 

 usually more open. 

 Stem-leaves oblanceolate or elliptic; bracts lanceolate. 28. S. trinervata. 



Stem-leaves obovate, thick; bracts ovate. 29. S. mollis. 



VIII. Wakdianae. 

 One species. 30. S. Wardii. 



26. PETRADORIA Greene. Rock Goldenbod. i. P. pumiia. 



27. ETTTHAMIA Nutt. Bushy or Fragrant Goldenbod. 



Outer bracts broader than the inner, which are obtuse. 1. E. camporum. 



Outer bracts narrow, all acute; lateral ribs of the leaves rather prominent. 



2. E. occidentalis. 



28. OLIGONEURON Small. Rough Goldenbod. i. o. canescens. 



29. MONOPTILON T. & G. l. M. belKdiforme. 



30. TOWNSENDIA Hook. 

 Bracts acuminate. 



Caulescent biennials or short-lived perennials. 



Stems spreading, with branches from the base, which surpass them in length. 



1. T. grandiflora. 

 Stems erect or nearly so, simple or with short branches above. 



Stems over 3 dm. high, generally branched; basal leaves oblanceolate. 

 Involucre 1.5-2 cm. broad, naked. 2. T- eximia. 



Involucre 2-3 cm. broad, generally subtended by leaves. 3. T. VreelandH. 

 Stems 1-2 dm. high, generally simple and monocephalous, sometimes several 

 from one root ; basal leaves spatulate. 4. T. Parryi. 



Acauiescent perennials, depressed, monocephalous. 



Plant pilose or hirsute. 5. T. alpina. 



Plant arachnoid-lanuginose. 6. T. condensata. 



Bracts acute or obtuse. 



Plant with evident leafy stems. 



Stems 5-20 cm. high; mostly annuals and biennials. 

 Pappus of disk- and ray-flowers elongate bristles. 



Leaves linear or oblanceolate; pappus of the rays nearly as long as that of 



the disk-flowers. 7. T. florifer. 



Leaves spatulate; pappus of the ray-flowers much shorter than that of the 

 disk-flowers. 8. T. ambigua. 



Pappus of the rays reduced to a crown of short squamellae. 



Bracts of the involucre in 3 series; pubescence of the stem appressed; 



leaves linear. 9. T. Fendleri. 



Bracts in 2 series; pubescence of the stem not strictly appressed; earlier 

 leaves, spatulate. 10. T. strigosa. 



Stem usually evident, but short, 1—5 cm. long; mostly cespitose perennials. 

 Leaves more or less cinereous. 



Outer bracts roimded-obtuse at the apex; achenes almost glabrous. 



11. r. montana. 

 Outer bracts acute; achenes pubescent. 



Heads distinctly pedimcled; hairs of the achenes not glochldiate-capi- 

 tellate. 12. T. scapigera. 



