THISTLE FAMILY 923 



or elliptic, sulphur-yellow, glossy. Perhaps scarcely distinct from the preceding. 

 Geyser formations: n Wyo. Mont. Au-S. 



6. G. Williamsii Rydb. Probably biennial; stem 3-6 dm. high, branched 

 above, loosely floccose; leaves linear or linear-lanceolate, decurrent, .5-10 cm. 

 long; inflorescence large, corymbosely i)aniculate; involucre 6 mm. high, only 

 slightly tomentose at the base; bracts broadly ovate, acute, light straw-colored 

 or white. Woods: Mont. Mont. Au. 



7. G. microcephalum Nutt. Perennial, with a taproot; stem slender, 3-5 

 dm. high, simple below; leaves linear or the lower oblanceolate, densely floccose; 

 inflorescence a narrow panicle; involucres campanulate, 4-,5 mm. high; bracts 

 straw-colored to pearly-white, lance-ovate, acute. Along streams: Calif. — Ida. 

 —B.C. 



8. G. Macounii Greene. Biennial, with a taproot; stem 5-8 dm. high, 

 corymbosely branched above, glandular-pubescent, loosely tomentose above; 

 leaves numerous, lanceolate to linear, white-tomentose beneath, 5-10 cm. long; 

 heads numerous; involucres hemispheric, glabrous, about 5 mm. high; bracts 

 ovate or the inner lanceolate, all acute, white or straw-colored, turning rusty. 

 G. decurrens Ives, not L. G. Ivesii Nels. & Macbr. Open ground: N.S. — Pa. — 

 N.M.— Ariz.— B.C. Plain— Submont. Jl-S. 



9. G. palustre Nutt. A low spreading annual; stem at first erect, later 

 diffusely branched, with spreading branches, 5-20 cm. high; leaves 1-2 cm. long; 

 involucres 3-4 mm. high; bracts oblong to linear, brown, or the inner with white 

 tips. Wet places: Alta.— Neb.— N.M.— Calif.— B.C. Plain— Submont. My- 

 Au. 



10. G. uliginosum L. Annual; stem at first simple, erect, later diffusely 

 branched, with ascending or spreading branches, .5-20 cm. long; leaves 2-4 cm. 

 long, 3-4 mm. wide; bracts oblong to linear, mostly acute, brown. Wet places: 

 Newf.—Va.— Colo.— Utah— Ore.— B.C.; n Eu. Plain— Mont. Jl-Au. 



11. G. exilifolium A. Nels. Low annual; stem branching at the base; 

 branches decimibent or adsurgent, 8-12 cm. long, sparingly floccose; leaves 2-4 

 cm. long; involucres aboiit 3 mm. high; bracts lanceolate, acute, brown below, 

 white-tipped. G. angustifoUum A. Nels., not Lam. Wet places: Colo. — Wyo. 

 Submont. — Mont. Jl-S. 



12. G. Grayi Nels. & Macbr. Strict and simple annual; stem 1-3 dm. high, 

 appressed-tomentose; leaves all linear, appressed-tomentose, 1-4 cm. long; invo- 

 lucres about 3 mm. long; bracts oblong to Unear, wholly brown, or the innermost 

 with lighter tips, obtuse. G. stridum A. Gray, not Moench. Wet places: Wyo. 

 — N.M. — Ariz. Submont. — Mont. Au-S. 



13. G. ustulatum Nutt. Perennial, with a short rootstock; stem 1-3 dm. 

 high, loosely floccose; leaves 2-8 cm. long, rather loosely floccose on both sides, 

 white beneath, greener above; glomerules of the heads arranged in a narrow 

 dense spike-like panicle; invohicres about 5 mm. long; bracts ovate, abruptly 

 short-cuspidate, brown, shining. Closely related to G. purpureum of the At- 

 lantic States. In sahne soil: B.C. — Mont. — Calif. Ajj-Jl. 



58. ADENOCAULON Hook. 



Perennial herbs, with rootstocks. Leaves alternate, with winged petioles 

 and dilated blades. Inflorescence paniculate, the peduncles beset with stalked 

 glands. Heads manj^-flowered, discoid. Involucres turbinate of few thin 

 herbaceous bracts. Marginal flowers pistillate, 4-lobed or somewhat 2-lipped. 

 Central flowers hermaphrodite, sterile, broadly funnelform, deeply 4-5-cleft, all 

 white. Anther sagittate and the am-icles minutely caudate. Achenes obovoid 

 or clavate, very obtuse, with stipitate glands above. Pappus none. 



1. A. bicolor Hook. Stem erect, 3-10 dm. high, more or less floccose; leaf- 

 blades deltoid-cordate, 5-10 cm. long, sinuate-dentate or somewhat lobed, soon 

 green and glabrate above, densely white-tomentose beneath; involucres 2. .5-3 

 mm. high, turbinate; bracts 4 or 5, ovate, acute, reflexed in fruit; achenes 4-6, 



