238 COMPOSITE. (composite family.) 



15. DIPLOPAPPUS, Cass. Double-bristled Aster. 



Heads many-flowered, radiate ; the rays 8-12, pistillate. Scales of the invo- 

 lucre imbricated, appressed, narrow, 1 -nerved or keeled, destitute of herbaceous 

 tips. Receptacle flat, alveolate. Achenia flattish. Pappus double ; the outer 

 of very short and small stiff bristles, the inner of capillary bristles as long as 

 the disk-corolla. — Perennials with corymbose or simple heads : disk-flowers 

 yellow ; rays white or violet. (Name composed of din\6os, double, and ird-nnos, 

 ■pappus, the character which distinguishes the genus from Aster.) 

 § 1. Rays violet, showy: head solitary, pretty large: involucre much imbricated.' 

 achenia silky : bristles of the inner pappus all alike. 



1. D. linariifolius, Hook. Stems (6'- 20' high) several from the same 

 woody root, mostly simple, very leafy ; leaves rigid, spreading, linear, strongly 

 1 -nerved, smooth, rough-margined. — Dry soil : common. Sept., Oct. 



§ 2. Rays white: heads small, corymbed: involucre shorter than the disk, imbricated 

 in about 3 rows : achenia smoothish : bristles of the inner pappus unequal, some 

 of them thickened at the tip : leaves rather large, scattered, membranaceous, veiny, 

 entire. 



2. D. Timbellatus, Torr. & Gr. Smooth, leafy to the top (2° -6° high) ; 

 leaves lanceolate, elongated, taper-pointed and tapering at the bas* (3' -6'' long) ; 

 heads very numerous in compound flat corymbs ; scales of the involucre rather 

 close, obtusish. — Moist thickets: common, especially northward. Aug. 



3. D. amygdalinus, Torr. & Gr. Smooth or roughish above, leafy ; 

 leaves ovate-lanceolate, acute, abruptly narrowed at the base ; scales of the involu- 

 cre loose, obtuse. — Low grounds, New Jersey, Penn., and southward. Aug. — 

 Too near the last ; but lower, rougher, and with broader and shorter leaves. 



4. D. COrnifdlillSj Dark Stem (l°-2° high) pubescent, bearing few 

 heads on divergent peduncles ; leaves elliptical or ovate-lane olate, conspicuously pointed 

 at both ends, ciliate, hairy on the veins underneath. — Woodlands, E. Massa- 

 chusetts to Kentucky, and southward along the mountains. July -Sept. 



16. BOLTONIA^ I/Her. Boltonia. 



Heads many-flowered, radiate ; the rays numerous, pistillate. Scales of the 

 hemispherical involucre imbricated somewhat in 2 rows, appresscd, with narrow 

 membranaceous margins. Receptacle conical or hemispherical, naked. Ache- 

 nia very flat, obovate or inversely heart-shaped, margined with a callous wing, 

 or in the ray 3-winged, crowned with a pappus of several minute bristles and 

 usually 2-4 longer awns. — Perennial and bushy-branched smooth herbs, pale 

 green, with the aspect of Aster: the thickish leaves chiefly entire, often turned 

 edgewise. Plowers autumnal : disk yellow : rays white or purplish. (Dedicated 

 to James Bolton, an English botanist of the last century.) 

 * Heads middle-sized, loosely corymbed. 



1. B. asteroides, L'Her. Leaves lanceolate ; achenia broadly oval ; pap- 

 pus of few minute bristles and no awns. — Moist places along streams. Penn- 

 sylvania (Bartram), and southward along the Alleghanies : rare. Oct. — Plant 

 usually 6° high. 



