238 COMPOSITES. (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 dtTrXoos, double, and TraTnroff, 

 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. Iinariif61ius, 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. umbellatus, Torr. & Gr. Smooth, leafy to the top (2 -6 high); 

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

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

 close, obtusfeh. 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. COrnif61iU8, Darl. Stem (l-2 high) pubescent, bearing few 

 heads on divergent peduncles ; leaves elliptical or ovate-lanceolate, 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. BOLT6NIA, L'Her. BOLTONIA. 



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

 Tiemispherical involucre imbricated somewhat in 2 rows, appressed, 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. Flowers 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. 



