MISCELLANEOUS PLANTS 



175 



to an association of inland xerophilous plants that in places descend 

 to the sea-border. We would therefore expect that Anona would 

 illustrate the principle exemplified by many tropical genera, such as 

 Barringtonia, Calophyllum, Clerodendron, Cordia, Guettarda, Morinda, 

 Sccevola, Terminalia, etc., that where a genus comprises both coast 

 and inland species only the coast species possess seeds or seed-vessels 

 adapted for effective dispersal by currents. This principle, which 

 is laid down in the second chapter of my book on Plant Dispersal, 

 might be considerably extended now, and the indications especially 

 concerning Anona will be stated below. But a few remarks on the 

 station characteristics of the genus are first required, as well as some 

 preliminary observations on its means of dispersal. 



The capacity of the genus for adapting itself to very different 

 stations is remarkable. Some species are at home in the humid 

 conditions of the dense mountain forests; others thrive in the drier 

 conditions of the open- wooded districts ; others grow in the savannas 

 and grassy plains; others are found in the sandy plains near the 

 coast, and others in the desert rocky regions in the company of 

 xerophytic Cactacece, Agaves, and Acacias. A few live in inland 

 and coastal marshy districts, and one is the associate of the man- 

 groves at the borders of estuaries and in the swamps at the sea- coast. 

 Probably the xerophytic habit is most typical of the Anonas of our 

 own day; but as indicative of a tendency to resume, what I would 

 regard as the primeval habit and station of the genus, these plants 

 even in their driest stations tend to gather along the streams, and 

 where the conditions are too arid for permanent streams they may 

 be found in the dry rocky beds of the channels that serve as water- 

 courses only during the rains. I would consider that the genus was 

 primarily a denizen of wet forests in warm latitudes, and that it has 

 often become adapted to drier climates during the differentiation 

 of climate in later ages. 



The modes of dispersal of these plants may be now discussed. 

 The question is at once raised when we contrast the distribution of 

 Anona palustris, the only species common to the eastern and western 

 hemispheres, with other species that are restricted to one or other 

 of the two hemispheres. Dr. Safford in a letter to Prof. Harshberger, 

 which is given below, strikes a true note regarding this tree when 

 he writes : " If it were birds that distributed the seeds, why would 

 not the more attractive species be just as widely dispersed? The 

 seeds may possibly be borne by currents." The answer to this 

 query' is indicated below, and it would seem, as far as these data 

 can guide us, that although birds and other creatures may be effec- 

 tive agents in local dispersal, the currents come into play when 

 broad tracts of ocean have to be crossed. That Anona seeds are 

 swallowed by fruit-eating birds of the pigeon family is stated by 

 Gosse in his Birds of Jamaica (pp. 308, 315 ; 1847). Both the Pea 

 Dove (Zenaida amabilis) and the White-belly Pigeon (Peristera 

 jamaicensis) feed upon them. Parrots no doubt feed on the fruits, 

 though I don't know whether they would swallow the seeds. One 

 of the Mexican species is named " the little custard apple of the 

 parrots " (Safford, p. 55). Pigs, iguanas and alligators are also 



