540 COMPOSITAE (COMPOSITE FAMILY) 



38. BOLOPHYTA Nutt. 



An acaulescent caespitose perennial, with the ligule wanting, the corolla 

 reduced to a truncate tube which is obscurely notched at the front and back. 

 Parthenium . 



1. Bolophyta alpina Nutt. Trans. Am. Phil. Soc. 7: 347. 1841. Densely 

 tufted on a thick branching caudex, depressed, rising only 3-5 cm. high: 

 leaves crowded, silvery-canescent with a fine appressed pubescence, and 

 villous in the axils, spatulate-linear, 2-3 cm. long, entire: heads solitary and 

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

 branaceous scales. Parthenium alpinum. " On rocks near the Three Buttes," 

 Rocky Mountains in Wyoming (at 7,000 feet). (Nuttall.) 



39. OXYTENIA Nutt. 



Shrubby perennial with erect branches. Leaves alternate, 3-5-parted into 

 filiform divisions, or the upper ones often sparse and entire. Involucral bracts 

 about 5, somewhat coriaceous, the tips rigidly acuminate. Bracts of the 

 receptacle slender, chaffy, with cuneate-dilated tips. Pistillate flowers about 

 5, destitute of corolla; staminate flowers 10-20. Young achenes obovate, very 

 villous with long soft hairs, terminated by a large areola. Pappus none or a 

 mere vestige. 



1. Oxytenia acerosa Nutt. PI. Gamb. 172. 1848. Stems canescent, half- 

 woody, 1-2 m. high, sometimes leafless and rush-like, sometimes covered with 

 leaves 1.5 dm. or less long: heads 4 mm. high, numerous, in dense panicles. 

 Dry alkaline plains; southern Colorado to California. 



40. IVA L. 



Ours coarse herbs with thickish alternate or opposite leaves and small 

 nodding heads of greenish-white flowers. Involucre hemispherical, the bracts 

 few and rounded. Receptacle with chaff-like, linear or spatulate bracts. 

 Marginal flowers of the head pistillate, 1-5 in number, the corollas tubular 

 or none; disk-flowers perfect, with 5-lobed funnelform corolla and undivided 

 style. Anthers almost distinct. Achenes flattened, glabrous. Pappus none. 



Tall coarse plants; the heads in panicled crowded spikes . . 1. I. xanthifolia. 



Low and often clustered stems; the heads solitary axillary . . . 2. I. axillaris. 



1. Iva xanthifolia Nutt. Gen. 2: 185. 1818. Tall and coarse, 7-18 dm. 

 high, pubescent, at least when young: leaves mainly opposite, broadly ovate, 

 ample, coarsely or incisely serrate, acuminate, 3-4-ribbed at base, puberu- 

 lently scabrous above: panicles axillary and terminal: outer involucral bracts 

 5, broadly ovate and herbaceous; the inner of as many membranaceous, 

 dilated-obovate or truncate ones, which are strongly concave at maturity and 

 half embrace the obovate-pyriform and glabrate achenes. From New Mexico 

 to Idaho and the Saskatchewan. 



2. Iva axillaris Pursh, Fl. 743. 1814. Stems or branches nearly simple, 

 ascending, 1-4 dm. high: leaves obovate or oblong to nearly linear, obtuse, 

 entire, sessile, 1-3 cm. long, even the uppermost usually much surpassing the 

 mostly solitary heads in their axils: bracts of the involucre connate into a 4 

 or 5-lobed or sometimes parted or merely crenate cup. From New Mexico 

 to Dakota and the Saskatchewan, and westward. 



41. DICORIA T. & G. 



Diffusely branched annuals of the desert area. Upper leaves alternate. 

 Inflorescence loosely paniculate. Involucral bracts 6 or 7, distinct; the 5 

 outer ones herbaceous; 1 or 2 of the inner ones much larger, scarious and sub- 



