GENUS 67. 



THISTLE FAMILY. 



487 



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. 

 Ac inomeris squarrosa Nutt. Gen. z: 181. 1818. 

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

 Verbesina alternifolia Britton ; Kearney, Bull. Torn 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' 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"-j," broad ; heads small, numerous. 



Leaves alternate ; rays white. i. P. virginica. 



Leaves opposite ; rays yellow. 2. P. occidentalis. 



Involucre hemispheric, f-\2" broad; heads few, large. 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 stem 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. 



