322 



THE JOURNAL OF BOTANY 



biennial, and it may bo of still lonf:jer duraiion. But witbont 

 cultural experiments tliis point cannot l)e satisfactoi-ily deter- 

 mined. 



TROPICAL AMERICAN RUBIACE^E.— VII. 

 By H. F. Wernham, D.Sc, F.L.S. 



(Continued from Journ. Bot., 1915, p. 15.) 

 VII.— The Genera. 



The ^vbole family of Rubiacea3, as at present constituted, 

 comprises considerably over 400 genera. Of tbese, less tban one 

 balf occur in the American Tropics ; the number being, as I 

 compute it in the present work, 182. 



Of this number, again, the very large majority are peculiar to 

 the New World, and nearly all of these aro confined to the Tropics, 

 the Rubiaceoe being essentially a tropical family. 



The exceptions, with representatives in both hemispheres, are 

 relatively few, but worthy of note. They are as follow : 



CiNCHONOiDE^. HedyotideaB: Oldenlandia, Anotis, ■''Pentodon. 

 — Rondeletieai : Lindenia. — Nauclese : Uncaria, Cephalanthus. — 

 MussoBudeffi : ■•'Sabicea. — Gardenieae : Bandia.—B.iimeliesQ : ''■Ber- 

 tiera. 



CoFFEOiDE^. Guettardeas : Gicettarda, Antirrhcea. — Ixoreoe : 

 Coffea, Ixora. — Psychotrieo3 : Mai^ouria, PsycJiotria, Geoi)liila, 

 Cephaelis. — Paederiea3 : Pcederia. — Anthospermese : Nertera. — 

 Morindeae : Morinda. — Spermacoceae : '-Diodia, Hemidiodia, 

 ■'S'permacoce, ■''Mitracarinmi. — GalieaB : Sherardia, Galium, Bubia. 



A total of 27 genera. Of these, the six marked with' an asterisk 

 are represented in the Old World only in Africa" and the neigh- 

 bouring tropical islands (Madagascar and the Mascarine Islands). 

 The rest, with very few exceptions, occur generally throughout 

 the Tropics ; a few, notably the Galieae (infra), are distributed 

 throughout the world, temperate as well as tropical. The Galiece 

 form a tribe of essentially temperate habitat. 



These statements go to show that the evolution of Rubiaceae 

 in the Tropics of the New World has proceeded very largely on 

 individual lines ; as is to be expected, in view of the wide and 

 (geologically) long separation between the two areas concerned. 



Distribution. — Our scope does not permit us to enter into any 

 closeness of detail regarding the distribution of the genera within 

 the area in question ; but a few of the main facts may be of ser- 

 vice in the identification of some groups. The warmer regions of 

 the New World, regarded from the standpoint of the occurrence 

 of the genera under consideration, fall into six groups, which are 

 dealt with briefly in succession below : 



(1) Northern area, including southern Florida, southern Cali- 

 fornia, and northern Mexico. Comparatively few of our genera 



* See Engler : Sitz. Kon. Preuss. Akad. Wiss. 1905, vi, " Uber floristische 

 Verwandtschaft zwisehen dem tropischen Afrika und America," etc. 



