818 COMPOSITAE (COMPOSITE FAMILY) 



lanceolate, acute and entire at both ends ; heads corymbed ; rays white, tinged 

 with purple, not twice the length of the bristly involucre. —Fields and waste 

 places ; a very common weed. June-Get. (Nat. in Eu.) 



7. E. rambsus (Walt.) BSP. (Uaisv F.) Stem panicled-corymbose at 

 the summit, roughish like the leaves with minute appressed hairs, or almost 

 smooth; leaves entire or nearly so, the upper lanceolate, scattered, the lowest 

 oblong or spatulate, tapering into a slender petiole ; rays white, twice the 

 length of the minutely hairy involucre. {E. strigosus Muhl.) — Fields, etc., 

 common. June-Oct. — Stem smaller and more simple than the preceding, with 

 smaller heads but longer rays. Var. discoideus (Robbins) BSP., with the 

 rays minute, scarcely exceeding the involucre, occurs in s. N. E. and N. Y. 



§ 2. CAEN6TUS Nutt. Bays inconspicuous, in several rows, scarcely longer 

 than the simple pappus ; annuals. 



8. E. canadensis L. (Horse-weed, Bdtter-weed.) Bristly-hairy ; stem 

 erect, wand-like, 0.1-3 m. high; leaves linear, mostly entire, the radical cut- 

 lobed ; heads very numerous and small, cylindrical, panicled. (Leptilon Britton.) 



Waste places, etc., a common weed, now widely diffused over the world. 



July-Get. — Ligule of the ray-flowers much shorter than the tube, white. 



9. E. divaricatus Michx. Diffuse and decumbent, 1-3 dm. high ; leaves 

 linear or awl-shaped, entire ; heads loosely corymbed ; rays purple ; otherwise 

 like no. 8. {Leptilon Raf.) — Ind. to Minn., Neb., and south w. 



§ 3. TRIMORPHAEA (Cass.) Reichenb. Like § 2, hut with a series of filiform 

 rayless pistillate flowers icithin the outer row of ray-flowers ; biennial or 

 sometimes perennial. 



10. E. acris L., var. asteroides (Andrz.) DC. Hirsute-pubescent or smooth- 

 ish ; stem erect, 2-5 dm. high ; leaves lanceolate or the lower spatulate-oblong, 

 entire ; heads several or rather numerous, racemose or at length corymbose, 

 nearly hemispherical, about 1 cm. long ; involucre minutely glandular-puberu- 

 lent, or somewhat hirsute toward the base ; rays purplish or bluish, equaling or 

 a little exceeding the copious pappus. (Var. droebachensis Blytt ; E. droeba- 

 chiensis G. F. Mull.) — Rocky banks and clearings, lower St. Lawrence, n. N. B., 

 n. Me., L. Superior, Rocky Mts., westw. and northw. July, Aug. (Eu.) 



24. SERICOCArPUS Nees. White-topped Aster 



Heads 12-20-flowered, radiate ; rays about 5, fertile, white. Involucre some- 

 what cylindrical or club-shaped ; the bracts closely imbricated in several rows, 

 cartilaginous and whitish, appressed, with short and abrupt often spreading 

 green tips. Receptacle alveolate-toothed. Achenes short, inversely pyramidal, 

 very silky ; pappus simple, of numerous capillary bristles. — Perennial tufted 

 herbs, 2-7 dm. high, with sessile somewhat 3-nerved leaves, and small heads 

 mostly in little clusters, disposed in a flat corymb. Disk-flowers pale yellow. 

 (Name from o-tiplkSs, silky, and Kapir 6s, fruit.) 



* Pappus rusty ; leaves sparingly serrate, veiny, rather thin. 



1. S. asteroides (L.) BSP. Somewhat pubescent; leaves oblong-lanceolate 

 or the lower spatulate, ciliate ; heads rather loosely corymbed, obconical ; 

 involucre 5-9 mm. long. {S. conyzoides Nees.)— Dry ground, s. Me. to 0., 

 and south w. June-Aug. 



* * Pappus ichite ; leaves entire, obscurely veined, firmer and smaller. 



2. S. linifblius (L.) BSP. Smooth, slender ; leaves linear, rigid, obtuse, 

 with rough margins, tapering to the base ; heads narrow, in close clusters, few- 

 flowered ; involucre 4-7 mm. long. {S. solidagineus Nees.) — Thickets, s. N. E. 

 to G., and southw. June-Aug. 



3. S. bifoliatus (Walt.) Porter. Hoary-pubescent ; leaves obovate or oblong- 

 spatulate, short (1-2.5 cm. long), vertical, both sides aUke ; heads rather loosely 



