238 coMrosiT.E. (compositf. family.) 



15. DIPLOPAPPUS, Cciss. Double-bristled Aster. 



Ikiuls nuiiiy-flowcrcd, railiatc ; tlic rays 8-12, i)istillatc. Scales of the invo- 

 lucre imbricated, appicsised, narrow, 1-iierved or keeled, destitute of lierbuceous 

 tips. Ixeeeptaclc tlat, alveolate. Acliciiia Hattish. rapi)us double ; the outer 

 of very short and small stifi' bri-stle.s, the inner of capillary bristles as long as 

 tlie disk<orolla. — Tcrennials with corymbose or sini])le heads : disk-flowers 

 vcUow ; rays white or violet. (Name coniposed of StTrXooy, doublef^id nuTTTros, 

 piifj/ius, the character which distinguishes the genus from Aster.)^ 

 § 1. Rays violet, showy: head solilari/, pretty large: involucre much imhricaled : 

 achniia silky : bristles of the inner jiapjms all alike. 



1. D. Iinariif61ius, Hook. Stems (6'- 20' high) several from the same 

 woody root, iuu.-.tly siiii|)le, very leafy ; leaves rigid, spreading, linear, strongly 

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



§ 2. Bays white: heads small, corymhfd : inrolnrre shorter than the disk, imhricaUd 

 in about 3 rows: acheniu smooth i sh : bristles of the inner pappus unequal, some 

 of them thickened at the tip : leaves ralhi-r large, scattered, membranaceous, veiny, 

 entire. 



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

 leaves lanc(olate, elonijutid, taper-pointed and tapering at the base (3' -C 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-la nreolale, aruie, abruptly narrowed at the base ; scales of the involu- 

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

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



4. D. COrnifdliUS, Darl. Stem (l°-2° high) pubescent, bearing few 

 heads on direrqent peduncles ; leaves elliptical or ovate-lanceolate, conspicuously pointed 

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

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



16. BOLTONIA, L'llcr. Boltoxia. 



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

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

 memhranaceons margins. Rcccj)tacle conical or hemispherical, naked. Aelie- 

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

 or in the ray 3-winged, crowned with a ])a])pus of sbveral minute bristles and 

 tisnally 2-4 longer awns. — Perennial aiul bushy -branched smooth herbs, ])ale 

 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'lkr. Leaves lanceolate ; achcnia broadly oval ; pap- 

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

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

 usually 6° high. 



