airysogonum. COMPOSITE. 243 



B. tomentosa, Nutt. 1. c. Canescent throughout with soft and close pannose tomentum, 

 no hirsute or villous liairs, when glabrate hardly at all scabrous : stem a foot or two high, 

 rarely only a span high : leaves all obtuse, green above, generally wJiitish beneath ; radical 

 and lower cauliue elongaJ;ed-oblong and petioled ; upper cauliue usually ovate-oblong or oval, 

 sometimes subcordate-ovate, short-petioled or sessile heads fewer, in low specimens almost 

 solitary and longer-peduncled. — Torr. & Gray, Fl. ii. 282. B. pumiki, Nutt. I.e. Sllpliium 

 pumilum, Michx. Fl. ii. 146. S. tomentosum, pumilum, & retlculatum? Pursh, Fl. ii. 578, 579. 

 S. Asteriscus, var. pumilum, Wood, Bot. 442. Polijmnia Caroliniana, Poir. Diet. v. 505. — 

 Dry pine barrens, X. Carolina to Florida, Arkansas, and Missouri. 



Var. dealbata, Torr. & Gray, 1. c. More robust and leafy, 2 or 3 feet high, branch- 

 ing at summit and bearing more numerous and shorter-peduncled heads: cauliue leaves 

 broader and more sessile, densely white-tomentose beneath ; lower broadly cordate, upper 

 often deltoid (with or without a subcordate base), either obtuse or acute. — Texas, Drum- 

 mond. Hall, Reverrhon., a very soft-canescent form. Varies into a less canescent state, 

 approaching B. Texana, the leaves scabrous above (var. 7, Torr. & Gray, 1. c), Arkansas, 

 Louisiana, and Texas. 



# * Stems commonly low and with long monocephalous peduncles ; the earliest often produced 

 from 'near the root, and sca|iiforni, the later from leafy stems or branches: leaves variable, all 

 attenuate at base, disposed to be pinnatilid or lyrate. 



B. subacaulis, Nutt. 1. c. Barely cinereous with minute often hispidulous pubescence (or 

 the peduncles sometimes hirsute), soon green, becoming a foot or so high and leafy: leaves 

 of oblong-linear or oblong-spatulate outline, .irregularly sinuately or lyrately pinnatifid, with 

 short obtuse lobes : akenes narrowly obovate-oval, merely carinately costate on the inner 

 face. — Torr. & Gray, Fl. ii. 282. Silphium subacaule, Nutt. in Am. Jour. Sci. v. 301 ; DC. 

 Prodr. V. 512. 5. NuttalUanum, Torv. Ann. Lye. N. Y. ii. 216, as to syn. — Florida, in dry 

 pine barrens ; first coll. by Ware. 



B. lyrata, Benth. Canescent with minute white or gray tomentum : leaves at length 

 greenish above, variously lyrate-pinnatifld ; the lateral lobes oblong or narrower, obtusely 

 dentate, sometimes incised : akenes obovate, the costa of the inner face strongly carinate. 



— PL Hartw. 17; Gray, PI. Fendl. 78, & PI. Wright, i. 103. B. incisa, Torr. & Gray, Fl. 

 ii. 282. Silphium NuttalUanum, Torr. Ann. Lye. N. Y. ii. 216, excl. syn. — Plains and hills, 

 W. Texas and Arkansas to Arizona. (Mex.) 



"Var. macrophylla. Radical leaves often a foot long, lanceolate-oblong or spatulate, 

 either merely crenate or pinnatifid at base : later flowering stems sometimes 2 or 3 feet high. 



— S. Arizona, LcMmow. 



72. CHRYS6G-0NUM, L. (Greek name of some plant in Dioscorides. 

 Linnaeu.s gives tlie derivation of his genus from -^pvcros, golden, and yovv, knee ; 

 of no obvious application.) — Gaertn. Fruct. ii. 436, t. 174 ; Lam. 111. t. 713 ; DC. 

 Prodr. V. 510; Torr. & Gray, Fl. ii. 274; Benth. & Hook. Gen. ii. 350, excl. 

 syn. 3Ioonia, &c. ; Gray, Proc. Am. Acad. xvii. 216. Diotostephus, Cass. Diet. 

 xlviii. 543. — Single species : fl. spring and summer. 



C. Virginianum, L. Perennial from creeping rootstocks and sometimes by runners, 

 pubescent, often hirsute, flowering acaulescently from the ground, also with stems a span to 

 a foot high, bearing 3 or 4 pairs of long-petioled leaves ; these ovate, mostly obtuse and 

 crenate; cauliue rarely subcordate and equalling or shorter than tlieir petioles, or the radical 

 obovate with cuneate attenuate base : peduncles solitary in the forks and terminal, all but the 

 radical ones elongated : involucre one-third and yellow rays half inch long. — Spec. ii. 920 

 (Pluk. Aim. t. 83, f. 4, & 242, f. 3) ; Walt. Car. 217 ; Michx. FL ii. 148; Torr. & Gray, L c. 

 C. Virginianum & C. Diotustephns, DC. 1. c. Diotostephus repens, Cass. 1. c. — Dry ground, 

 S. Pennsylvania to Florida. Varies considerably according to age and season, usually low 

 when blossoming begins. 



Var. dentatum, Gray. Leaves deltoid-ovate, acute, coarsely dentate-serrate, the tip 

 and teeth, also tlie tips of the bracts of the outer involucre, terminated by a more conspicu- 

 OU& callous mucro. — Bot. Gazette, viii. 31. —High Island at the falls of the Potomac above 

 Washington, J. DonneU Smith, Ward, Vasey. 



