Genus 79. 



THISTLE FAMILY. 



505 



79. HYMENOPAPPUS L'Her. ; Michx. Fl. Bor. Am. 2< 103. 1803. 



Perennial or biennial, erect herbs, with angled stems, alternate or basal, mostly pinnatifid 

 or dissected leaves, and corymbose or solitary, small or rather large discoid heads, of white 

 or yellow flowers. Involucre hemispheric or broadly campanulate, its bracts 6-12 in 1 or 2 

 series, nearly equal, mostly appressed, colored, petal-like, the margins and apices scarious. 

 Receptacle small, naked. Rays none. Disk-flowers all perfect and fertile, their corollas with 

 slender tubes and reflexed or spreading campanulate 5-lobed limbs, the lobes, ovate. Anthers 

 entire at the base. Style-branches with short conic appendages. Achenes obovoid or obpyra- 

 midal, 4-5-angled, the faces usually prominently 1-3-nerved. Pappus of 10-20 thin obtuse 

 scales, sometimes very short or none. [Greek, membrane-pappus.] 



About 7 species, natives of southern and central North America and Mexico. Type species : 

 Hymenopappus scabiosaeus L'Her. 



Bracts of the involucre broadly ovate or oval, bright white. 1, H. carolinensis. 



Bracts obovate to oblong, green or with white tips. 

 Heads numerous, 4"-6" broad ; biennials. 



Achenes puberulent ; corolla white. 2. H. corymbosus. 



Achenes densely villous. 



Plant glabrate, or loosely woolly; corolla dull white. 3. H. tenuifolius. 



Plant densely white-woolly ; corolla yellow. 4. H. flavescens. 



Heads few, 6" 12" broad; corolla yellow; perennial. 5. H. filifolius. 



i. Hymenopappus carolinensis (Lam.) Porter 



Fig. 45 2 9- 



Rothia carolinensis Lam. Journ. Hist. Nat. 1 ; 16. pi. 



1. 1792. 

 Hymenopappus scabiosaeus L'Her. ; Michx. Fl. Bor. 



Am. 2 : 104. 1803. 

 Hymenopappus carolinensis Porter, Mem. Torr. Club 



5: 338- 1894. 



Biennial; stem woolly-pubescent or glabrate, 

 leafy below, corymbosely branched and nearly 

 naked above, 2-3 high. Basal and lower leaves 

 petioled. 4'-6' long, 1-2-pinnately parted or deeply 

 pinnatifid into linear or oblong, obtuse or ob- 

 tusish lobes, more or less white-tomentose be- 

 neath, green and glabrate above ; upper leaves 

 few, smaller, sessile, less divided ; heads com- 

 monly numerous, corymbose. 6"-io" broad; 

 bracts of involucre oblong, ovate or oval, some- 

 times slightly obovate, thin, bright white, pu- 

 berulent or glabrate ; corolla-lobes about as long 

 as the throat, white ; achenes puberulent or pu- 

 bescent ; pappus of very small nerveless scales, 

 shorter than the width of the top of the achene. 



In dry sandy soil, Illinois to Texas, east to South 

 Carolina and Florida. March-June. 



White-bracted Hymenopappus. 



2. Hymenopappus corymbosus T. & G. 



Corymbed or Smooth White Hymeno- 

 pappus. Fig. 4530. 



Hymenopappus corymbosus T. & G. Fl. N. A. 2 : Z7 2 - 

 1842. 



Biennial; stem glabrous, or nearly so. corymbosely 

 branched and nearly naked above, i-2 high. Lower 

 and basal leaves petioled, 1-2-pinnately parted into 

 linear or nearly filiform, acute or acutish, glabrous 

 lobes, or somewhat tomentose beneath ; upper leaves 

 few, much smaller and less divided, or the upper- 

 most reduced to linear scales ; heads corymbose, nu- 

 merous, 4"-6" broad ; bracts of the involucre obo- 

 vate to oblong, puberulent, their tips greenish white; 

 corolla white, its lobes about as long as the throat; 

 achenes puberulent; pappus scales small, nerveless, 

 shorter than the width of the top of the achene. 



On dry prairies, Missouri and Nebraska to Texas. 

 Summer. 



