THISTLE FAMILY 983 



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

 developed, it bears numerous flbrous-flesliy roots. 

 Heads more or less nodding. 



Heads discoid; crown short, with fleshy-fibrous roots. I, Pi'dtcI. 



Heads radiate; rootstock well developed. II. Amplectrxtts. 



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. Amplectkntks. 



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. 



XVTTI. iNTEGERRnrr. 

 Heads less than 15 mm. high and broad. 

 Plants equally leafy throughout. 



Leaves or their divisions not narrowly linear or flliform. 

 Leaves merely toothed or entire, not pinnatifld. 



Leaf-blades oval, elUptic, or obovate, usually obtuslsh; heads few; 



plants cespitose. III. Occidextales. 



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. Triangul\res. 



Leaf-blades neither triangular nor cordate. 



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

 stocks. V. Serrae. 

 Plant low, 2^ dm. high; heads few. 



Heads radiate. - XVL Crasstjli. 



Heads discoid. XVII. Rapifolii. 



Leaves pinnatifld. VI. EREMopHiLr. 



Leaves or their divisions linear-filiform; plants usually sufTruticose at the 

 base. VII. LOXGILOBI. 



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 



saUently dentate. 

 Heads discoid; leaves saiiently dentate. 



XVII. Rapifolh. 



Heads radiate; leaves callous-denticulate. 



Leaves glabrous. VIII. GL-\ucescextes. 



Leaves tomentose. IX. Fouosr. 



Stem slender; rootstock usually more or Jess cespitose: leaves 



neither callous-denticulate, nor saiiently and closely den- 

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

 Basal leaves entire, more or less white-tomentose; 



X. Caxi. 



Basal leaves, at lea^t most of them, toothed or pinnatifld. 

 Leaves and stem more or less floccose. tardily becoming 



glabrate. XI. Tomextosi. 



Leaves and stem glabrous or slightly floccose when yoimg. 



XII. Altiei. 



Heads turbinate, sohtary. ^}Vr' StrBNTDT. 



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



Rootstock very short, erect, of short duration. \^uth numeroxis fleshy-fibrous 



roots; leaves dentate or entire. x. , j 



Tall bOK-plants. 5-15 dm. liigh; basal leaves long-pet loled. 



^^ XV. Hydrophili. 



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



short-petioled. 

 Leaves sharply and densely dentate. X\ I. Cr.vssuu. 



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



- XVIII. IXTEGERRIML 



Annuals. 



discoid, or with minute rays. 



XX. VtTLG 



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



I. PUDICI. 



^^^llrJlfTe ^pW-iV^Ta\T^ntire; midvein of t^e leav^^ lon.-villous. 



Auricles of the upper leaves large and usually toothed; midvem ff^i^^^]f^f^^ '^'^ 

 TTM.ris l-To mmfhigh. narrowly campanulate. 3. S. pudicus. 



