GENUS 67. 



THISTLE FAMILY. 



heads. Involucre small, flattish, of few spreading or recurved narrow bracts. Receptacle 

 convex or conic, becoming globose, chaffy. Ray-flowers neutral, yellow or white, sometimes 

 wanting. Disk-flowers perfect, fertile, embraced by the chaff. Anthers entire at the base. 

 Style-branches of the disk with acute appendages. Achenes flattened, more or less winged, 

 spreading in all directions on the globose receptacle. Pappus of 2 or 3 finally spreading 

 smooth awns, sometimes with 2-3 smaller awns or scales. [Name unexplained.] 



Two species, of eastern North America, the following 

 typical. 



i. Ridan alternifolius (L.) Britton. Wing- 

 stem. Yellow Iron weed. Fig. 4487. 



Coreopsis alternifolia L. Sp. PI. 909. 1753. 

 Actinomeris squarrosa Nutt. Gen. <z : 181. 1818. 

 Actinomeris alternifolia DC. Prodr. 5: 575. 1836. 

 Verbesina alternifolia Britton ; Kearney, Bull. Torr. Club 



20: 485. 1893. 



Perennial; stem puberulent or glabrous, narrowly 

 winged, or wingless, simple, or branched near the 

 summit, leafy, 4-9 high. Leaves oblong-lanceolate 

 or lanceolate, acuminate, serrate, serrulate or entire, 

 rough or roughish on both sides, gradually narrowed 

 to the sessile base, or short-petioled, 4'-i2' long, 

 \'-2\' wide, alternate, or the lower opposite and 

 slender-petioled ; heads numerous, i'-2 r broad, co- 

 rymbose-paniculate; rays 2-10, yellow; involucre of 

 few lanceolate, at length deflexed bracts; disk glo- 

 bose, yellow ; achenes broadly winged or nearly wing- 

 less, sparingly pubescent; pappus 2 divergent awns. 



In rich soil, New Jersey to Iowa, Kansas, Florida and 

 Louisiana. Winged ironweed. Aug.-Sept. 



68. PHAETHUSA Gaertn. Fr. & Sem. 2 : 425. 1791. 



Perennial, pubescent or scabrous herbs (some tropical species shrubby), with alternate 

 or opposite dentate leaves often decurrent on the stem and branches, and corymbose or soli- 

 tary heads of both tubular and radiate yellow or white flowers, or the rays sometimes want- 

 ing. Involucre campanulate or hemispheric, its bracts imbricated in few series. Receptacle 

 convex or conic, chaffy, the chaff embracing the disk-flowers. Ray-flowers pistillate or neu- 

 tral. Disk-flowers perfect, mostly fertile, their corollas with an expanded 5-lobed limb, 

 usually longer than the tube. Style-branches of the disk-flowers with acute papillose append- 

 ages. Achenes flattened, or those of the ray-flowers 3-sided. Pappus of 2 (1-3) subulate 

 awns, sometimes with 2 or 3 intermediate scales. [The daughter of Helios.] 



A large genus, mainly natives of the New World. Besides the following, about 6 others occur 

 in the southern and southwestern United States. Type species : Phaethusa americana Gaertn. 



Involucre campanulate, 2" 3" broad ; heads small, numerous. 



Leaves alternate ; rays white. 



Leaves opposite ; rays yellow. 

 Involucre hemispheric, j"-i2" broad; heads few, large. 



1. P. virginica. 



2. P. occidentalis. 



3. P. helianthoides. 



i. Phaethusa virginica (L.) Britton. Small 

 White or Virginia Crownbeard. Fig. 4488. 



Verbesina virginica L. Sp. PI. 901. 1753. 



Perennial ; stem densely puberulent, terete or winged, 

 simple or branched, 3-6 high. Leaves usually thin, 

 alternate, ovate, roughish above, puberulent, canes- 

 cent or glabrate beneath, acute or acuminate at the 

 apex, 4'-io' long, i'-3' wide, contracted at the base 

 into winged petioles, the uppermost sessile, lanceo- 

 late, smaller, often entire ; heads corymbose-panicu- 

 late at the ends of the stern and branches, numerous, 

 6"-io" broad ; involucre oblong-campanulate, 2"-3" 

 broad, its bracts narrowly lanceolate, erect, obtuse, 

 pubescent ; rays 3-5, obpvate, white, pistillate ; achenes 

 minutely pubescent, winged or wingless; pappus of 

 2 slender awns, or sometimes none. 



In dry soil, Pennsylvania to Virginia, Illinois, Mis- 

 souri, Kansas, Florida and Texas. Aug.-Sept. 



