THISTLE FAAIILY 1001 



heads 8-15; involucres 8-10 mm. high, campanulate; bracts shorter than the 

 disk; achenes striate, glabrous. Perhaps not distinct from S. columbiamis. Wet 

 places : Wyo. — Colo. — Utah — Ida. Submont. — Subalp, Je-Au. 



111. S. solitarius Rydb. Stem glabrous, 3-4 dm. high; lower leaves thin, 

 glabrous, wing-petioled; blades oval, subentire, about 5 cm. long; middle leaves 

 lanceolate, clasping at the base, the uppermost reduced, linear-lanceolate or 

 subulate; heads sohtary, about 2 cm. high; bracts narrowly linear, black-tipped; 

 ligules light yellow, almost 1.5 cm. long; achenes glabrous. Meadows: n Wyo. 



112. S. megacephalus Nutt. Stout, more or less floccose perennial, with 

 a thick rootstock; stem simple; leaves oblong, oblanceolate, or hnear, 1-2 dm. 

 long, rather thick, entire-margined or merely denticulate; heads solitary or sel- 

 dom 2-3, 15-20 mm. high and about 1.5 cm. broad; bracts linear, thick, acumin- 

 ate, often surpassed by the subulate calyculate ones; disk light brownish yellow; 

 ligules orange, 15-20 mm. long; achenes glabrous. Mountam regions: Ida.— 

 Mont.— Alta.— B.C. Mont. Subalp. Jl-Au. 



113. S. vulgaris L, Annual; stem erect, 1-4 dm. high, more or less pilose 

 or glabrate; leaves sinuate-pinnatifid, glabrous or slightly arachnoid, with oblong 

 to rounded incised divisions, the upper auriculate-clasping; heads cymose* mvo- 

 lucres campanulate-cylindric, 7-9 mm. high, glabrous; bracts Unear-subulate, 

 black-tipped, the calyculate ones minute; rays none; achenes canescent-puberu- 

 lent. Waste places: Lab.— Newf.—N.C— Calif.— Alaska; nat. from Eu. F-Au. 



114. S. palustris (L.) Hook. Stem arachnoid-villous when young, 1.5-5 

 dm high, rather fleshy, strongly striate; low^er leaves with winged petioles; blades 

 lanceolate in outUne, sinuately dentate to laciniate-pmnatifid, the upper hnear, 

 more or less clasping; cyme crowded, corymbiform; mvolucres hemispheric, 

 about 8 mm high, not calyculate; bracts narrowly linear-lanceolate, acuminate; 

 ligules broad and short, oblong, light yellow, 4-5 mm. long; achenes glabrous 

 Wet ground: Lab.— la.— Sask.— Alaska and the Arctic coa^t; Eu. Subboreal 



— Sxiharciic. My-Jl. 



130. TETRADYMIA DC. 



Low and rigid shrubs; leaves or branches, or both covered with white perma- 

 nent or deciduous tomentum. Leaves alternate, entire with smaller secondary 

 ones fascicled in their axils, or the primary leaves modified into spines. Heads 

 Sid Involucre cylindric or oblong; bracts 4-6, concave, overlapping. Re- 

 Sacle small, fiat, naked. Corolla with elongate cyhndric tube and lanceo- 

 Ste spr^^^^^^^ lobes longer than the short campanulate throat Anther^ sagit- 

 tate afthe base, with triangular tips. Style-branches flat, with short obtusely 

 conical tips Achenes terete, 5-nerved, short. Pappus of numerous fine, white, 

 minutely scabrous bristles. 



Primary leaves oblanceolate. 



Primary leaves linear. c.^-mjcyht 2. T, canescens. 



?S? &1 f-tsTrnS.trSW recurved. Pungent-pointecL;^^se.ondary 

 leaves fascicled. 

 Primary leaves linear -subulate ^ j ^^ linear, or spatulate-Iinear glabrate 



Primary leaves erect, slenaer, secuau^iy icav^ ^i, t. glabrata. 



ni ^S^- J- « .,*!«• cT^inA-Hlrp- sepondarv leaves oblanceolate. 



Primary leaves spreadmg, stiff, spme-iiice, seconudJ-> i^av ^ ^ Nuttallii. 



. -u * t._r at ipa«?t flip imier broadly oval; branches wliite-tomeatose 

 Heads .V-9-flowered; bracts 5-6, at least tne imier oruauiy 



throughout; plant spmy. p„«vpd 6. T. spinosa. 



Spines 5-12 mm. long, more or less curved. ^^ j. longispina. 



Spines 15-30 mm. long, straight. 



« . . XT +4- Qlimh 2-5 dm high; branches canescent, short and 



1. T. inermis Nutt. Shrub, ^ ^,^"^- J^^^^^^ ^^ linear-oblanceolate, white- 

 crowded, very leafy; primary ^,^^^7^^^ cylindric bracts 



Mont, Jl-S. 



