AND GENERA OF PLANTS. 371 



Subtribe IV. — TAGETiNEiE. 

 *RIDDELLIA. 



Capitulum many-flowered, heterogamous; rays feminine, three to five, coria- 

 ceous, persistent, dilated, equally and obtusely three-lobed, six-nerved ; discal 

 florets hermaphrodite, tubular, five-toothed, the dentures glandular. Stig- 

 mas subcapitate, obtuse, minutely pubescent. Involucrum cylindric, com- 

 posed of eight ingrafted leaflets. Achenium slender and conic, prismatic, 

 smooth. Pappus paleaceous, five or six-leaved, segments lanceolate, acumi- 

 nate, nerveless, similar in the ray. Receptacle naked, minute. — A slenderly 

 branching, aromatic herb, with alternate, oblong-linear, subtomentose leaves; 

 branchlets corymbose, three to five-flowered ; persistent rays apparently yel- 

 low, (reddish-orange after inflorescence;) involucrum densely sericeous with 

 long hairs. — (Named in respect of Professor Riddell, a botanist, who has 

 explored the interior of Texas.) 



Riddellia * Tagetince. 



Hab. 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 per- 

 fectly flat after inflorescence, as in Zinnia. 



*SOLENOTHECA. 



Capitulum few-flowered, heterogamous; rays feminine, very few and small, 

 (two or three.) Involucrum an entire, even, cylindric tube, with a short, 

 five-toothed border. Receptacle naked. Achenium fusiform, compressed, 

 somewhat four-sided, partly stipitated at the base, pubescent. Pappus pa- 

 leaceous, palese elongated, setiform, of equal length, but unequal thickness, 

 ciliated, and almost plumose on the margin. — A small annual of Peru, with 

 slender, spreading branches; leaves opposite and alternate, pinnatifid. Flow- 

 ers terminal, fastigiate; liguli few and very small. Nearly allied to Tagetes, 

 but with a very different pappus, and a peculiar habit. — (Named from aaT^v^v, 

 a tube, and Qy^xvi, a sheath, in allusion to the cylindric calyx.) 



