338 NATURAL HISTORY OF PLANTS. 



Eugenia in four. The genera Decasjpermum^ BJwdomyrUis, Bliodamnia 

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

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

 can ; but many of them, as Psidium and Pimento , are cultivated in 

 the old vrorld. To the latter belong the Barringtoniece with regular 

 androDcium, except Gustavia and Grias which, like the Lecythece 

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

 NapoleonecB known, belonging 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 BhizophoracecSy chiefly with those of which 

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

 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 interp etiolate 

 stipules of the Bhizophorece. The Comhretacece with opposite leaves 

 have sometimes the flower of the Myrtacece] 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 

 find 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 have 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 



^ Not to speak of Punica, which has doubt- American Schizocalyx of Berg, a genus not 

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



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