1184 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



linear, with recurved margins, closely brown-reticulate, the throat coveredl 

 with close concentric brown-purple stripes ; lobes of the corona linear, 8 mm. 

 long; ovary glabrous. 



6. Dictyanthus ceratopetalus Donn. Smith, Bot. Gaz. 18: 208. 1893. 



Moi-elos, Puebla, and Oaxaca. Guatemala and El Salvador; type from 

 plains of Santa Rosa, Guatemala. 



Stems scandent, hirsute, woody below; leaves ovate-cordate, 2 to 7 cm. long, 

 acute, densely pubescent; cymes 1 or few-flowered, short-pedunculate; corolla 

 2.5 to 4.5 cm. broad, brown-purple, closely reticulate throughout. 



20. POLYSTEMMA Decaisne in DC. Prodr. 8: 602. 1844. 



Stems twining, suffrutescent below, hirsute ; leaves long-petiolate, ovate- 

 cordate; cymes umbelliform, few-flowered; calyx 5-parted; corolla short-cam- 

 panulate or subrotate, the throat naked ; corona adnate to the gynostegium,^ 

 composed of 5 ligulate scales and 20 smaller filiform ones ; stigma plane. 



Leaves with a closed basal sinus 1. P. viridiflora. 



Leaves with a broad open shallow sinus. 



Corolla about 8 mm. long 2. P. scopulorum. 



Corolla about 20 mm. long 3. P. rupestris. 



1. Polystemma viridifiora Decaisne in DC. Prodr. 8: 602. 1844. 

 Veracruz ; type from Orizaba. 



Leaves hirtellous ; peduncles as long as the leaves, 3 or 4-flowered ; corolla 

 green, puberulent. 



2. Polystemma scopulorum T. S. Brandeg. Univ. Calif. Publ. Bot. 6: 189. 1915. 

 Type from San Geronimo, Oaxaca. 



Leaves ovate-cordate, 8 cm. long or less, acuminate, sparsely hirsute ; cymes 

 few-flowered, the peduncles about 2.5 cm. long; corolla rotate, reticulate; 

 larger corona scales narrowly oblong, tridentate at apex. 



3. Polystemma rupestris T. S. Brandeg. Univ. Calif. Publ. Bot. 7: 330. 1920. 

 Type from Barranca de Panoaya, Veracruz. 



Leaves ovate-cordate, 5 to 8 cm. long, acuminate, sparsely hirsute; cymes 

 few-flowered, about as long as the leaves ; corolla campanulate, reticulate 

 within, the lobes acute or acuminate; larger corona scales deeply trilobate, 

 the smaller ones filiform ; follicles smooth. 



21. ROTHROCKIA A. Gray, Proc. Amer. Acad. 20: 295. 1885. 



Plants scandent, herbaceous or suffrutescent ; leaves long-petiolate, cordate ; 

 cymes pedunculate, umbelliform or racemiform ; calyx 5-parted ; corolla rotate, 

 the lobes narrow ; corona simple, 5-lohate ; stigma produced into a column ; fol- 

 licles smooth. 



The following are the only species known. 



Corona lobes 2-dentate, not appendaged, with 2 short lateral teeth. 



1. R. cordifolia. 

 Corona lobes with caudate lateral processes, or with long exterior filiform 

 appendages. 

 Corolla yellowish green ; corona scales with lateral caudate processes about 



1.5 mm. long 2. R, umbellata. 



Corolla purple-black ; corona scales with exterior filiform appendages about 

 4 mm. long 3. E. fruticosa. 



