THISTLE FAMILY 983 



Perennials with a moro or less developed rootstock or caudex ; if the latter is less well- 

 developed, it bears iminerous flbrous-fleshy roots. 

 Heads more or less iioddinj;. 



Heads discoid; crown short, with fleshy-fibrous roots. I. PuDlci. 



Heads radiate; rootstock well developed. II. Amplectentes. 



Heads not nodding. 



Heads more than 15 mm. liigli and 20 mm. broad, solitary (seldom 2-3). 

 Plant low, le.ss than 2 dm. high, witli rootstocks; bractlets short. 



II. Amplectentes. 

 Plant tall, .S-5 dm. high, stout, with a short crown and a cluster of fleshy- 

 flbrous roots. 

 Bractlets linear-flUform, almost equalling the involucre; bracts not black- 

 tipped. XIX. Meg.-vcephali. 

 Bractlets sliort; bracts usually tipped with I)lack. 



XVIII. INTEGERRIMI. 



Heads less than 1.5 mm. hish and broad. 

 Plants equally- leafy (liroufjhout. 



Leaves or tluir divisions not narrowly linear or filiform. 

 Leaves merely tootlied or entire, not pinnatifld. 



Leaf-blades oval, elliptic, or obovate, usually obtusish; heads few; 



plants cespitose. III. OctTDEXT.\LE.s. 



Leaf-blades triangular or ovate to linear-lanceolate, distinctly acute; 

 heads usually many. 

 Leaf-blades, at least the lower ones, triangular or cordate; plants 

 growing in clumps, with fleshy-flbrous roots. 



IV. Trl\ngul.u?es. 

 Leaf-blades neither triangular nor cordate. 



Plant tall, 5-15 dm. liigh; heads numerous; plants -vvith root- 

 stocks. V. Serrae. 

 Plant low, 2-4 dm. liigh; heads few. 



Heads radiate. XVI. Crassult. 



Heads discoid. XVII. Rapifolii. 



Leaves pinnatifld. VI. Eremopiiili. 



Leaves or their divisions linear-flliform; plants usually suffruticose at the 

 base. VII. Longilobi. 



Plants with the stem-leaves more or less reduced upwards. 

 Rootstock well developed, horizontal or ascending, woody. 

 Stem leafy, more than 2 dm. high. 



Heads campanulate, rarely solitary. 



Stem stout; rootstock not cespitose; leaves calloas-denticulate or 

 saUently dentate. 

 Heads discoid; leaves saUently dentate. 



XVII. Rapifolii. 

 Heads radiate; leaves caUous-denticulate. 



Leaves glabrous. VIII. Gl.'Vucescentes. 



Leaves tomentose. IX. FOLiosi. 



Stem slender; rootstock usually more or less cespitose; leaves 

 neither callous-denticulate, nor saliently and closely den- 

 tate; stem-leaves in the larger forms asually pinnatifld. 

 Basal leaves entire, more or less white-tomentose. 



X. C.\NI. 

 Basal leaves, at least most of them, toothed or pinnatifld. 

 Leaves and stem more or less floccose, tardily becoming 



glabrate. XI. Tome'xtosi. 



Leaves and stem glabrous or slightly floccose when young. 



XII. AUREI. 

 Heads turbinate, solitary. XIII. Subnudi. 



Stem subscapose, less than 2 dm. high. XIV. Andicolae. 



Rootstock very short, erect, of short duration, with numerous fleshy-flbrous 

 roots; leaves dentate or entire. 

 Tall bog-plants, 5-15 dm. high; basal leaves long-petioled. 



XV. Hydi«)PHILi. 

 Meadow or wood-plants, 2-5 dm. high; basal leaves comparatively 

 short-petioled. 

 Leaves sharply and densely dentate. XVI. Cr.'VSSULI. 



Leaves entire-margined or denticulate, seldom sinuate-dentate. 



XVIII. INTEGERRIMI. 



Annuals. 



Plant branched, more or less viscid; heads discoid, or with minute rays. 



XX. VijLG.\RE.S. 



Plant simple, more or less floccose: heads radiate. XXI. Palustres. 



I. PUDICI. 



Heads 12-20 mm. high, broadly campanulate. 



Auricles of the upper leaves small and entire; mid vein of the leaves long-villoas. 



1. S. accidens. 

 Auricles of the upper leaves large and usually toothed; midvein of the leaves not con- 

 spicuoasly villous. 2. .S. chloranlhus. 



Heads 8-10 mm. high, narrowly campanulate. 3. S. pudicus. 



