338 NATURAL HISTORY OF PLANTS. 



Eugenia in four. The genera Decaspermum, Bhodomyrtus, Bhodamnia 

 and FenzUa alone are limited to the tropical regions of Asia and 

 Oceania. All the other genera of this series are exclusively Ameri- 

 can ; hut many of them, as Fsidium and Pimenta, are cultivated ia 

 the old world. To the latter helong the Barringtonieoe with regular 

 andrcecium, except Gustavia and Orias which, like the Lecythece 

 with irregular andrcecium, are from tropical America. Of the two 

 NapoleonecB known, helonging each to a monotypal (?) genus, one is 

 American and the other African. Finally, of sixty-four genera, 

 nineteen are exclusively American ; three only are common to the 

 old and new world, viz. : Myrtus, Eugenia, and Metrosideros.^ 



Affinities. — The Myrtacece have very numerous affinities, very 

 close especially with the BMzophoracece, chiefly with those of which 

 the ovary is inferior. The number, ordinarily reduced, of the stamens 

 and ovules, is chiefly what distinguishes the flowers of the latter, 

 whilst the fruit is characterized by its structure and the mode of 

 germination of its seed. The organs of vegetation are often the 

 same in both families ; but the Myrtacece have not the interpetiolate 

 stipules of the Bhizophorece. The Gombretacece with opposite leaves 

 have sometimes the flower of the MyHacece; but the unilocular ovary 

 and the placentae scarcely salient in its cavity easily distinguish them. 

 The embryo is often constructed like that of the Pomegranates, the. 

 flower of which is quite different and has petals not without reason 

 compared- with those of the Lythrariacece. These latter have ordi- 

 narily a receptacular tube of special organization, and the calyx is 

 most frequently valvate, like that of the Pomegranates ; but we shall 

 flnd that the ovary is generally free at the bottom of the receptacular 

 tube, whilst in the Pomegranates, which have nearly the same 

 perianth, the ovary is completely " adherent." The fruit, the seed 

 and the embryo are equally different, and the opposite-leaved Myr- 

 tacece ha\e ordinarily punctuate leaves. The Melastomacece are 

 distinguished from the Myrtacece, either by the nervation of their 

 leaves, or by the organization of their anthers, or by the relative 

 position of the ovary in the receptacular cavity, or by all these 

 characters united. The Melastomacece have besides almost always an 



1 Not to speak of fimiea, which has douht- American ScMzocalyx of Berg, a genus not 

 less teen introduced into America, nor of the adopted by all (B. H. Gen. 720, n. 59). 



