Iva. COMPOSITE. 245 



roundish and obtuse lobes: heads numerous, pauicuLite-cymose : lignles commonly longer 

 than broad : pappus a pair of short-subulate erect or at length spreading awns. — Nov Gen. 

 & Spec. iv. 260, t. 391 ; Gray, PL Wright, i. 103. P. incunum & P. ramo6issi7num, DC. Prodr. 

 V. 532. — Dry hills, W. Texas to Arizona. (Mex.) 

 P. argentatum, Gu.vy. Suffrutescent, a toot high, silvery-canescent Avith close tomcntum : 

 branches erect, rather leafless above, bearing conipai-atively large and few lieads (of 2 lines 

 in diameter) : leaves lanceolate to spatulate in outline, some entire or iucisely 2-o-toothed ; 

 the larger iucisely pinnatifid into 2 to 7 acute lateral lobes : pajjpus a pair of lanceolate 

 chaffy awns. — Bot. Mex. Bound. 8G. — S. W. borders of Texas, Digelow. (Adj. Mex., 

 Purrij, Palincr. Produces a gum or resin in JMexico.) 



* * * Perennial herb, with larger heads and leaves ; the latter undivided, tiiickish. 

 P. integrifolium, L. Stout, l to 3 feet high, minutely pubescent, corymbosely branched 

 above, the branches terminated by a dense cyme of many heads (these a quarter-inch high) : 

 leaves ovate-oblong or narrower, thickly creuatc-dentate, rarely doubly dentate or somewhat 

 incised, hisi)idulous-scabrous, prominently veiny fi'om a strong midrib ; radical a foot or 

 more long and tapering into a petiole ; upper cauline closely sessile and broad at base : pap- 

 pus a pair of small chaffy teeth or scales. — Spec. ii. 988 (Dill. Elth. t. 225 ; Pluk. Aim. t. 53 

 & 219) ; Lam. 111. t. 766 ; Willd. Hort. Berol. t. 4 ; Torr. & Gr.\y, 1. c. — Dry ground, Mary- 

 land to Illinois and Texas. 



§ 2. BoLonirxuM, Torr. & Gray. (^Bolopliyta, Nutt.) Ligule wanting, the 

 corolla being reduced to a truncate tube, which is obscurely notched at back and 

 front : acaulescent cespitose perennial. 



P. alpinuni, Tonu. & Gray, 1. c. Densely tufted on a thick branching caudex, depressed, 

 rising only an inch or two high : leaves crowded, silvery-canescent with a fine appressed 

 puliesceiu'C, and villous in the axils, spatulate-linear, barely inch long, entire: heads solitary 

 and nearly sessile among the leaves : pappus a pair of oblong-lanceolate membranaceous 

 scales. — Bo!ophi//a alpina, Nutt. Trans. Am. Phil. Soc. n. ser. vii. 347. — llocky Mountains 

 in Wyoming (at 7,000 feet), on rocks near the Three Buttes, Nultall. 



76. PARTHENICE, Gray. (nap^ei'iKi/, a poetical form of the word 

 from which the name of the preceding nearly related genus is derived.) — PI. 

 Wright, ii. 85 ; Benth. & Hook. Gen. 352. — Genus of a single species, allied 

 also to the succeeding genus. 



P. mollis, Gray, 1. c. Annual, with odor and savor of Artemisia, 4 to 6 feet high, panicu- 

 lately branched, minutely puberulent-cinereous throughout, wholly destitute of any coarser 

 jjitbesccnce : leaves membi-anaceous, all alternate, ovate, some of the larger (:is much as 10 

 or 12 inches long) subcordatc, acuminate, irregularly or doubly dentate, long-petioled : heads 

 small (2 lines broad), numerous in loose axillary and terminal somewhat leafy panicles, 

 mostly pedicellate : flowers greenish-white. — Hillsides and along streams, S. Colorado to 

 Arizona, Wright, Thurhcr, Leinmon, &c. Fl. autumn. 



77. IVA, L. (An unexplained name.) — American herbs or shrubs ; with 

 entire or dentate or dissected leaves, at least the lower ones opposite, and small 

 spicately or racemosely or paniculately disposed or scattered and commonly 

 nodding heads : fl. summer. — Lam. 111. 7GG ; Gasrtn. Fruct. t. 1G4; DC. Prodr. 

 V. 529. Iva & Cydachcena (Fresen.), Torr. & Gray, Fl. ii. 285 ; Benth. & 

 Hook. Gen. ii. 352. 



§ 1. CyCLACriJiNA. Heads naked-paniculate, inconspicuously bracteate : co- 

 rolla of the 5 fertile flowers a very short rudiment or none : leaves membranaceous, 

 from inciscly serrate to dissected, mostly petioled : flowers somewhat inclined to 

 polygamo-dioecious through abortion of the ovaries : annual herbs. — Gyclachcena, 

 Fresen. Ind. Sem. Hort. Franc. 1836, & Linn. xii. ; Torr. & Gray, 1. c. 285. 



