Genus 64.] 



THISTLE FAMILY. 



429 



22. Helianthus tuberosus L,. Jerusalem 

 Artichoke. Earth Apple. (Fig. 3919.) 



Helianthus tuberosus L. Sp. PI. 905. 1753. 



Perennial by fleshy thickened rootstocks, bearing 

 tubers; stems hirsute or pubescent, branched above, 

 6-i2 high. Leaves ovate or ovate-oblong, firm, 

 3-nerved near the base, narrowed, or "the lower 

 rounded, truncate or subcordate at the base, acumi- 

 nate at the apex, rather long-petioled, scabrous 

 above, finely pubescent beneath, serrate, 4 / -8 / long, 

 1 %.'-?/ wide, the upper alternate, the lower opposite; 

 heads several or numerous, 2 / -3^ / broad; involu- 

 cre hemispheric, its bracts lanceolate, acuminate, 

 hirsute or ciliate, squarrose; disk yellow; rays 12-20; 

 chaff of the receptacle acute and pubescent at the 

 summit; achenes pubescent. 



In moist soil, New Brunswick and Ontario to the 

 Northwest Territory, south to Georgia and Arkansas. 

 Often occurs along roadsides in the east, a relic of cul- 

 tivation by the aborigines. Now extensively grown 

 for its edible tubers. Called also Canada Potato, Gira- 

 sole, Topinambour. Sept. -Oct. 



Helianthus tuberosus subcanescens A. Gray, Syn. Fl. 1: Part 2: 280. 1884. 

 Lower; leaves densely white canescent beneath. Prairies, Minnesota to the Northwest Terri- 

 tory, south to Missouri. 



65. VERBESINA L. Sp. PI. 901. 1753. 

 [Actinomeris Nutt. Gen. 2: 181. 1818.] 



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

 alternate or opposite 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 wanting. 

 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 neutral. 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 appendages. Achenes 

 flattened, or those of the ray-flowers 3-sided, their margins winged or wingless. Pappus of 2 

 (1-3) subulate awns, sometimes with 2 or 3 intermediate scales. [ Name altered from Verbena.] 



A large genus, variously restricted by authors, mainly natives of the New World, 

 following, about 6 others occur in the southern and southwestern United States. 

 Involucre campanulate, 2"-$" broad; heads small, numerous. 



Leaves alternate; rays white. 



Leaves opposite; rays yellow. 

 Involucre hemispheric, 7" -12" broad; heads few, large. 



Besides the 



V. Virginica. 

 V. occidenlalis. 



Leaves ovate, sessile, serrate. 

 Leaves deltoid, petioled, coarsely dentate. 

 Involucre of a few, at length defiexed bracts; disk globose. 



3. V. helianthoides . 



4. V. encelioides. 



5. V. alternifolia. 



i. Verbesina Virginica L,. Small White 

 or Virginia Crownbeard. (Fig. 3920.) 



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, canescent or glabrate beneath, acute or 

 acuminate at the apex, 4 / -io / long, i / -3 / wide, con- 

 tracted at the base into winged petioles, the upper- 

 most sessile, lanceolate, smaller, often entire; heads 

 corymbose-paniculate at the ends of the stem and 

 branches, numerous, 6 // -io // ' broad; involucre 

 oblong-campanulate, 2 // ~3 // broad, its bracts nar- 

 rowly lanceolate, erect, obtuse, pubescent; rays 3-5, 

 obovate, white, pistillate; achenes minutely pubes- 

 cent, winged or wingless; pappus of 2 slender awns, 

 or sometimes none. 



In dry soil, Pennsylvania (according to Michaux), 

 Virginia to Illinois and Missouri, south to Florida and 

 Texas. Aug.-Sept. 



