COMI'OSITAK (COMPOSITE FAMILY) 799 



■;. B. nudata (Michx.) DC. A smooth perennial; the slender stem 3-8 dm. 

 nigh, simple or branched from the base, naked above, bearing small heads in a 

 flat-topped corymb. — Low pine barrens, N. J., and south w. Sept. 



19. B]IlLIS [Tourn.] L. Daisv 



Heads many-flowered ; the rays numerous, pistillate. Bracts of the involucre 

 herbaceous, equal, in about 2 rows. Receptacle conical, naked. Achenes 

 obovate, flattened, wingless, and without any pappus. — Low herbs, chiefly of 

 the Old World, either stemless, like the true Daisy, B. perennis L. (which 

 is found as an occasional escape from cultivation), or leafy-stemmed, as is the 

 following. (The Latin name, of uncertain derivation.) 



1. B. integrifdlia Michx. (Western D.) Annual or biennial, diffusely 

 branched, 1-4 dm. high, smoothish; leaves lanceolate or oblong, the lower 

 spatulate-obovate ; heads on slender peduncles; rays pale violet-purple. — 

 Prairies and banks, Ky., and south westw. May, June. 



20. CHAETOpApPA DC. 



Heads several-flowered, radiate ; disk-flowers often sterile. Involucral bracts 

 imbricated in 2 or more rows, the outer shorter. Receptacle flat, naked. 

 Achenes fusiform or compressed ; pappus of 5 or fewer thin nerveless scales, 

 alternating with rough bristly awns, or these wanting. — Low southwestern 

 branching annuals, with narrow entire leaves and solitary terminal heads ; rays 

 white or purple. (XafrT;, a bristle, and ir6,Tnro%, pappus.) 



1. C. asteroides DC. Slender, 0.5-3 dm. high, pubescent; involucres 

 slender, 4 mm. long; rays 5-12; achenes pubescent. — Dry grounds, Mo., 

 and southwestw. 



21. B0LT6nIA L'H^r. 



Heads many-flowered ; rays numerous, pistillate. Bracts of the hemispheri- 

 cal involucre imbricated somewhat in 2 rows, appressed, with narrow mem- 

 branaceous margins. Receptacle conical or hemispherical, naked. Achenes 

 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 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 

 BoUon, English botanist of the 18th century.) 



* Heads middle-sized, loosely corymbed. 



1. B. asteroides (L.) L'H&. Stems 0.2-2.5 m. high; leaves lanceolate; 

 involucral bracts acuminate ; pappus of few or many minute bristles and 2 awns 

 01' none. — Moist places along streams, Ct. to Neb., and southw. Aug.-Oct. 

 Var. DECtrRRENS (T. & G.) Engelm. A large form with the leaves alate-decur- 

 rent upon the stem and branches. (B. decurrens Wood.) — 111. and Mo. 



2. B. latisqu^ma Gray. Heads rather larger ; involucral bracts oblong to 

 ovate, obtuse or mucronate-apiculate ; pappus-awns conspicuous. — Prairies, etc., 

 w. Mo., Kan., and Okla. 



* * Heads small, panieled on the slender branches. 



3. B. diffusa Ell. Stem diffusely branched ; leaves lance-linear, those on 

 the branchlets very small and awl-shaped ; rays short, mostly white ; pappus of 

 several very short bristles and 2 short awns. — Prairies, etc., s. 111. to Ela. and 

 Tex. Aug.-Oct. 



23. Aster [Tourn.] L. Starwort. Frost-flower. Aster 



Heads many-flowered, radiate; the ray-flowers in a single .series, fertile. 

 Bracts of the involucre more or less imbricated, usually with herbaceous or leaf- 



