362 COMPOSITiE. Dysodia. 



volucre much longer than the pappus, marked with very large dots. Rays 

 linear-oblong, bright yellow. 



2. D. chrysanthemoides (Lagasca) : puberulent or glabrous, diffusely 

 branched ; leaves opposite, pinnately parted ; the lobes linear, toothed or in- 

 cised towards the summit; heads terminating the paniculate leafy branchlets; 

 scales of the campanulate involucre united at the base, scarious at the sum- 

 mit ; the involucriforin bracts (about 8) linear, entire, ciliate at the base; 

 ravs few, scarcely exceeding the involucre ; achenia pubescent ; pappus as 

 long as the involucre, rather longer than the corolla ; the scales dissected 

 into numerous slender bristles. — Lagasca, elench. Jwrl, Madr. p. 29; DC. ! 

 prodr. 5. f. 640. Dyssodia glandulosa, Cav. demoyist. hot. p. 202, not of 

 Less. Tasetes papposa. Vent. hort. Cels. t. 36 ; Michx. ! fl. 2. p. 132. 

 Boebera chr^^santhemoides, Willd.! spec. 3. p. 2125; Pursh, Jl. 2. p. 559. 

 B. glandulosa, Pers. syn. 2. j)- 459. 



Banks of rivers, and on prairies, on the Mississippi and Missouri, and their 

 tributaries, from St. Pierre River ! and Illinois ! to Louisiana ! Aug.-Oct. 

 — (l) Plant about a foot high, exhaling a very strong unpleasant odor. 

 Flowers golden yellow. — Willdenow gives Carolina and Florida as habitats 

 of this plant, doubtless incorrectly. It is also a Mexican species. 



114. RIDDELLIA. Nutt. in trans. Amer. phil. soc. {n. set.) 7. p. 371. 



Heads many-flowered, radiate ; the rays 3-5, ligulate, pistillate, dilated, 

 6-nerved, equally 3-lobed, persistent ; the disk-flowers tubular, perfect. In- 

 volucre cylindrical, composed of 8 scales united in a single series. Recep- 

 tacle small, naked. Corolla of the disk 5-toothed ; the teeth glandular. 

 Appendages of the style subcapitate, obtuse, minutely pubescent. Achenia 

 " slender and conic [obconical ?], prismatic, smooth." Pappus of the ray 

 and disk similar, of 5-6 lanceolate acuminate nerveless chafTy scales. — A 

 slender branching aromatic herb, with alternate oblong-linear and somewhat 

 tomentose leaves ; the branchlets corj^mbose, bearing 3-5 heads. Rays ap- 

 parently yellow, turning to reddish-orange. Involucre densely silky with 

 long hairs. 



R. tagetina (Nutt. 1. c.) 



" In the southern range of the Rocky Mountains, towards the sources of 

 the Platte. — A very elegant plant, with the habit of a Zinnia, but having the 

 involucrum formed of a single series of united sepals. The rays are very 

 remarkable, appearing as rigid as parchment, and remain perfectly flat after 

 inflorescence, as in Zinnia." Nuttall. — This genus is dedicated to Prof. John 

 L. Riddell, formerly of Ohio, now of New Orleans; author of a Synopsis of 

 the Floraof the Western States, published at Cincinnati in 1835 (pp. 116, 8vo.), 

 and of a Supplementary Catalogue of Ohio Plants (1836). This plant is un- 

 known to us, and we have taken the character from Mr. Nuttall's memoir. 

 So far as the description extends, it only differs from Tagetes in the persis- 

 tent rays, and the pubescence. We are not informed whether or not the 

 leaves present the large pellucid dots of the Tagetines. 



Subtribe 5. Helenie^, Cass., DC. — Heads mostly heterogamous and ra- 

 diate ; the disk-flowers perfect, but sometimes sterile. Receptacle naked or 

 chaffy. Anthers often blackish, the lobes frequently somewhat prodnced at 



