THISTLE FAMILY 983 



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

 developed, it bears numerous fibrous-fleshy roots. 

 Heads more or less nodding. 



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



Heads radiate; rootstock well developed. II. AMPLECTENTES 



Heads not nodding. 



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

 Plant low, less than 2 dm. high, with rootstocks; bractlets short. 



II. AMPLECTENTES. 



Plant tall, 3-5 dm. high, stout, with a short crown and a cluster of fleshy- 

 fibrous roots. 



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

 tipped. XIX. MEGACEPHALI. 

 Bractlets short; bracts usually tipped with black. 



XVIII. INTEGEBRIMI. 



Heads less than 15 mm. high and broad. 

 Plants equally leafy throughout. 



Leaves or their divisions not narrowly linear or filiform. 

 Leaves merely toothed or entire, not pinnatifid. 



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



plants cespitose. III. OCCIDENTALES. 



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-fibrous roots. 



IV. TRIANGULARES. 

 Leaf-blades neither triangular nor cordate. r 



Plant tall, 5-15 dm. high; heads numerous; plants with root- 

 stocks. V. SERRAE. 

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



Heads radiate. XVI. CRASSULI. 



Heads discoid. XVII. RAPIFOLII. 



Leaves pinnatifid. VI. EREMOPHILI. 



Leaves or their divisions linear-filiform; 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 callous-denticulate or 



saliently dentate. 

 Heads discoid; leaves saliently dentate. 



XVII. RAPIFOLII. 

 Heads radiate; leaves callous-denticulate. 



Leaves glabrous. VIII. GLAUCESCENTES. 



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 usually pinnatifid. 

 Basal leaves entire, more or less white-tomentose. 



X. CANI. 



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

 Leaves and stem more or less floccose, tardily becoming 



glabrate. - XI. TOMENTOSI. 



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, \th numerous fleshy-fibrous 



roots; leaves dentate or entire. 

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



XV. HYDROPHILI. 

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



short-petioled. 



Leaves sharply and densely dentate. XVI. CRASSULI. 



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



XVIII. INTEGERRIMI. 



Annuals. 



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



XX. VULGARES. 

 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-villous. 



1. S. accidens. 



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

 spicuously villous. 2. S. chloranthus. 

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



