508 



COMPOSITAE. 



VOL. III. 



with campanulate or cylindric, 5-cleft limb. Anthers entire or emarginate at the base. Style- 

 tips mostly truncate and obtuse. Achenes quadrangular, linear or oblong. Pappus of several 

 scales, obtuse or truncate and scarious at the apex. [Named for its resemblance to Picradenia.] 

 Two known species, natives of western North America, the following typical. 



i. Picradeniopsis oppositifolia (Nutt.) 



Rydb. Picradeniopsis. Fig. 4536. 

 Trichophyllum oppositifolium Nutt. Gen. 2 : 167. 1818. 



Bahia oppositifolium Nutt.; T. & G. Fl. N. A. z : 376. 

 1842. 



P. oppositifolia Rydb.; Britton, Manual 1008. 1901. 



Perennial, herbaceous ; stem densely cinereous, 

 much branched, 4/-I2' high, very leafy. Leaves 

 opposite, or the uppermost alternate, i'-ii' long, 

 palmately 2-5-parted into linear, obtuse or ob- 

 tusish, entire segments, finely cinereous on both 

 sides ; heads short-peduncled, 6"-o," broad ; invo- 

 lucre campanulate, or becoming hemispheric, its 

 bracts oblong, obtuse, densely tomentose ; rays 

 5-7, short; achenes linear-oblong, glandular-pu- 

 bescent; pappus of 4-8 spatulate to lanceolate 

 scales with thickened bases. 



On plains, especially in alkaline soil, South Da- 

 kota to Montana, Nebraska, Texas, New Mexico. 

 June-Sept. 



82. TETRANEURIS Greene, Pittonia 3 : 265. 1898. 

 [ACTINELLA Nutt. (i8i8), not Pers. (1807), nor Actinea Juss. (1803).] 

 Branched or scapose, villous-pubescent or glabrous, bitter and aromatic punctate herbs, 

 with alternate or basal, often punctate leaves, and small or rather large, peduncled heads of 

 both tubular and radiate, yellow flowers, or rays rarely wanting. Involucre hemispheric, 

 campanulate or depressed, its bracts imbricated in 2-3 series, appressed. Receptacle convex 

 or conic, naked. Ray-flowers pistillate and fertile, the rays 3-toothed, 4-nerved. Disk-flowers 

 perfect, fertile, their corollas with 4~5-toothed limbs. Anthers entire or minutely sagittate 

 at the base. Style-branches truncate and penicillate at the summit. Achenes turbinate, 5-10- 

 ribbed or angled, villous or pubescent. Pappus of 5-12 thin aristate, acuminate or truncate 

 scales. [Greek, four-nerved.] 



About 1 8 species, natives of western North America and Mexico. Besides the following, some 

 12 others occur in the western and southwestern parts of the United States. Type species: Te.ra- 

 neuris acaulis (Pursh) Greene. 



Stem leafy, branching; stem leaves linear; annual or biennial. i. T. linear [folia. 



Stems tufted, simple, scapose ; leaves basal ; perennials. 



Leaves narrowly linear ; branches of the caudex slender. 2. T. stenophylla. 



Leaves broader, linear to spatulate ; branches of the caudex short and thick. 



Bracts of the involucre acutish. 3. T. acaulis. 



Bracts of the involucre obtuse, rounded. 4. T. herbacea. 



i. Tetraneuris linearifolia (Hook.) Greene. 

 Fine-leaved Tetraneuris. Fig. 4537. 



Hymenoxys linearifolia Hook. Icon. pi. 146. 1837. 

 Actinella linearifolia T. & G. Fl. N. A. 2 : 383. 1842. 

 T. linearifolia Greene, Pittonia 3: 369- 1898. 



Annual or perhaps biennial ; stem usually diffusely 

 branched, finely hirsute, or glabrous, or woolly at 

 the base, slender, 6'-i5' high. Stem leaves narrowly 

 linear, sessile, 4'-ii' long, *"-i" wide; basal leaves 

 spatulate, often villous, much broader, obtuse, nar- 

 rowed into margined petioles; heads numerous, 

 slender-peduncled, 6"-8" broad; involucre broadly 

 campanulate, its bracts oblong, obtuse, pubescent, 

 distinct to the base, imbricated in about 2 series; 

 receptacle conic; rays 6-10, oblong; achenes pubes- 

 cent; pappus of 5 or 6 ovate awned scales. 



In dry soil, Kansas to Louisiana, Texas and New 

 Mexico. May-Sept. 



