MEXICAN AND CENTRAL AMERICAN UMBELLIFER^ II5 



note that the recent genus Neonelsonia, founded upon a single 

 species, has been strengthened by the discovery of a species 

 heretofore referred to Arracacia. 



The accompanying tables will serve to show the development 

 of our knowledge of the Umbelliferge of the region since Hems- 

 ley's presentation of the family in the Biologia. The numbers 

 given include only the native and named species. The endemic 

 genera are indicated b}^ asterisks. 



The genera are arranged in the sequence given by Drude in 

 Engler and Prantl's JVaiiirlichen Pflanzenfamilien, which is by 

 far the most masterly presentation of the group which has yet 

 appeared. The following purely artificial key to the genera 

 may be of service to those not familiar with them. 



Artificial Key to the Genera. 



Flowers in dense heads ; leaves usually with bristly or spiny-toothed 



margins 7. Eryngium. 



Flowers not in heads, evidently umbellate ; leaves not spiny-toothed. 

 Fruit conspicuously bristly. 



Fruit covered with hooked bristles. 



Leaves palmately divided, with broad segments. 



6. Sanicula. 

 Leaves ternately dissected, with filiform segments. 



21. Leptocatdis. 

 Fruit with bristles only on the ribs. 



Bristles barbed at tip ; stylopodium obsolete. 



39. Dauctis. 

 Bristles not barbed; stylopodium conical. ..9. Caucalis. 

 Fruit not bristly (except Osmorhiza) . 



Flowers in simple umbels (sometimes proliferous or even 

 irregularly branching in Hydrocotyle') . 



Fruit more or less stellate-pubescent 3. Boivlesia. 



Fruit not stellate-pubescent. 



Seed-face more or less sulcate or involute. 



Fruit narrow 10. Oreo?nyrr/iis. 



Fruit orbicular 11. Neogoezia. 



Seed-face not sulcate or involute. 



Stems creeping i . Hydrocotyle. 



Stems more or less erect and leafy. 



Leaves cuneate at base 5. Astericium. 



Leaves not cuneate at base. 



Leaves with naked petioles and reniform blades. 



2. Micropleura. 

 Leaves with tuft of hairs at top of petiole, and 

 ovate acuminate blades 4. Spananthe. 



