1148 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Two genera, Amsonia and Apocynum, are represented in Mexico only by 

 herbaceous species. It is possible that AUamanda cathartica L. may extend 

 into Mexico or at least be in cultivation. It is a woody vine with large showy 

 yellow flowers. 



Anther cells not appendaged at base ; plants never scandent. 

 Leaves all alternate. 



Carpels of the fruit many-seeded, dehiscent. Corolla salverform. 



1. PLUMEBIA. 

 Carpels 1 or 2-seeded, indehiscent. 



Corolla salverform; carpels about 1 cm. long 2. VALLESIA. 



Corolla funnelform; carpels much larger 3. THEVETIA. 



Leaves opposite or verticillate. 



Carpels of the fruit 1 or 2-seeded, almost wholly conrfete. Leaves ver- 

 ticillate 4. RAUWOLFIA. 



Carpels with more numerous seeds, free, at least above. 



Leaves mostly verticillate. Carpels long and slender, dehiscent. 



5. TONDUZIA. 

 Leaves opposite. 

 Calyx glandular within; carpels fleshy, usually indehiscent. 



Corolla salverform 6. TABERNAEMONTANA. 



Corolla funnelform 7. STEMMADENIA. 



Calyx eglandular ; carpels dry, dehiscent. 



Carpels slender, terete; seeds not winged; herbs or low shrubs. 



8. CATHARANTHUS. 

 Carpels broad, compressed ; seeds broadly winged ; large trees. 



9. ASPIDOSPERMA. 

 Anther cells appendaged at base and sometimes at apex ; plants usually 

 scandent. 

 Corolla with 5 scales in the throat ; leaves verticillate. Plants erect. 



10. NERIUM. 

 Corolla without scales ; leaves opposite. 



Tips of the anthers exserted from the corolla. 

 Corolla subrotate, the tube very short. 



Cymes umbel-like 11. THENARDIA. 



Cymes spikelike 12. FORSTERONIA. 



Corolla salverform, the tube elongate 13. PRESTONIA. 



Tips of the anthers not exserted. 



Corolla funnelform, the throat evidently dilated. 



Plants erect 14. MACROSIPHONIA. 



Plants scandent. 



Calyx eglandular 15. RHABDADENIA. 



Calyx glandular within. 

 Anthers with a subulate twisted appendage at apex. 



16. URECHITES. 

 Anthers not appendaged at apex, obtuse to acuminate. 



17. MANDE VILLA. 

 Corolla salverform. 



Calyx eglandular. Plants erect 18. HAPLOPHYTON. 



Calyx glandular within. 



Flowers racemose 19. ECHITES. 



Flowers cymose. 



Corolla tube twisted 20. STREPTOTRACHELUS. 



Corolla tube not twisted 21. SECONDATIA. 



