40 THE FLORA OF IOWA. 



pappus pale or tawny, short, very unequal; achenia turbinate, 

 villous. Flor. Co/., Port. Gr* Coin'. 



GRINDELIA, Willd. 



Heads many- flowered; the ray flowers generally present, pistillate, 

 the ligule elongated; disk-flowers perfect, the corolla tubular-funnel- 

 shaped, 5 -toothed. Involucre subglobose or hemispherical, the 

 scales imbricated in many rows. Receptacle naked, flat, foveolate. 

 Style with lanceolate, hispid appendages as long as the stigmatic 

 portion. Achenium smooth, oblong, or ovate, somewhat angled. 

 Pappus of 2 8 smooth, rigid, deciduous awns, shorter than the disk- 

 corollas. Biennial (?) perennial or suffruticose, often resiniferous, 

 Mexican and North American plants. 



401. G. SQUARROSA, Dunal. Glabrous and viscidly resinous ; stems 

 herbaceous from a perennial caudex, 1 2 •• high, corymbosely branch- 

 ed above : leaves somewhat rigid, glaucous and punctate, radical 

 ones spatulate-lanceolate, narrowed into a petiole, dentate or incised, 

 cauline mostly oblong, sessile and partly clasping, rather obtuse, 

 finely toothed or spinulose-serrate ; heads numerous, subglobose, 6" 

 broad ; the scales very rigid, close-appressed, but with very long re- 

 flexed, squarrose, subulate points, resinous; rays numerous, rather 

 narrow ; pappus of 2-4 verv rigid, deciduous bristles or awns. 

 /■'/or. Co/., Port. 6- Co;//. 



<Y( I, \< H/3:n A, 1 res 



Fertile and sterile flowers in the same head ; the former 5, in the 

 axils of the inner scales of the involucre, with no corolla or a mere 

 rudiment; the latter 10 15, with an obconical 5-toothed corolla (near- 

 ly destitute of proper tube); the central ones abortive. Scales of 

 the flattish hemispherical involucre usually 10, in 2 series; the exte- 

 rior 5, ovate, somewhat acuminate, thickish, herbaceous; the interior 

 dilated-obovate, truncate, membranaceous, at length loosely wrapped 

 around the achenia. Receptacle small, flat: the chaff linear -spatu- 

 late, usually wanting toward the center. Anthers slightly united, 

 tipped with an inflexed mucronate appendage. Style of the fertile 

 flowers deeply 2-cleft, linear, acutish; in the sterile flowers undi- 

 vided, radiate -penicillate at the apex. Achenia obovate, obcom- 

 pressed, somewhat turgid, not margined, glabrous, entirely destitute 

 of pappus; the staminate flowers with no rudiments of ovaries. 



408. C. XANTHIIFOLIA, Fres. A tall and coarse annual; the stem 

 simple, and more or less branched at the summit: leaves opposite, 

 ovate or sub cordate, acuminate, doubly or unequally serrate, 3 

 nerved, hirsute -canescent or pubescent beneath, somewhat scabrous, 

 on long petioles; heads small greenish, ebracteate, sessile and often 

 glomerate, disposed in compound terminal and axillary spikes, form- 

 ing a pyramidal panicle. Flor. A . I. 



426. HELIANTHUS LENTICULARIS, Dougl. Annual, scabrous or 

 hispid, branching, stout, 38- high; leaves ovate, alternate, acu- 

 minate, coarsely -serrate, 3' 6' long, 2' 4' broad, 3-nerved at the 

 base and suddenly narrowed into a petiole nearly as long as the leaf, 

 uppermost often lanceolate and entire; heads mostly panicled, pe : 

 duncled, 2 4' broad; scales of the involucre ovate, ciliate, abruptly 

 and conspicuously acuminate, in about 3 rows, spreading: rays 20 

 40, large; chaff of the flat receptacle nearly as long as the purplish 

 disk flowers, concave, carinate, tricuspidate, the middle point much 

 the strongest and dark colored; achenia finely appressed-pubescent; 

 pappus of two Lanceolate, chaffy awns. /•'/<>;-. ('<</., Port. 1S Con/. 



471. Centai rea Americana, Nutt. Stem erect, striate-grooved, 



sparingly branched, thickened under the heads; leaves sessile, gla- 



