320 NATURAL HISTORY OF PLANTS. 



fruit. What is more remarkable in this genus is that the situation 

 of the ovary is extremely variable, with all the gradations possible 

 from a total adherence to an entire independence of the gymsecium 

 completely superior, as is the case in certain Australian and New 

 Caledonian species of Xanthostemon. Mooria is scarcely distinct 

 from Metrosideros ; it has five pointed sepals, slightly imbricate, five 

 petals and somewhat numerous stamens, shorter than the calyx, with 

 an ovary semi-superior, the three cells of which enclose interiorly an 

 ascending placenta on which rise ovules indefinite in number, it is 

 true, but often inconsiderable. The fruit is loculicidal, and the 

 leaves are opposite, penninerved. It consists of small trees or shrubs 

 from New Caledonia and the neighbouring isles. Arillastrum, like- 

 wise New Caledonian, has nearly the flower of Metrosideros, tetra- 

 merous, with a very large number of stamens and two multiovulate 

 ovarian cells. But the capsular fruit, forming with the thickened 

 and hardened receptacle, a deep obconical cup, is wide at the summit, 

 and sets free a single pea-shaped seed, with thick fleshy embryo, and 

 thick folded cotyledons. The seminal coat is covered with a circle of 

 scales, resembling an aril and corresponding to as many aborted seeds. 

 The leaves are opposite, and the flowers axillary solitary or ternate 

 at the summit of a common peduncle. 



Eucalyptus (fig. 299-303) has given its name to a small sub-series 

 (Eucalyptece) constituted by it and the genus Angophora. The 

 flowers have a concave receptacle the margin of which bears a gamo- 

 sepalous calyx. In the genus Eucalyptus it is superiorly truncate 

 entire or very rarely divided into four short and distant teeth. The 

 name of the genus is derived from the corolla which here forms a 

 hood analogous to that represented by the calyx of Calyptranthes, 

 Acicalyptus, etc., and which, detaching itself circularly by the base, 

 falls off in a single piece at the time of anthesis (it is extremely rare 

 that it then divides into several segments). The stamens are very 

 numerous and have versatile anthers, with cells dehiscing longitudi- 

 nally. The capsular fruit, imbedded in the receptacle, opens from 

 the summit along the middle line of cells. The Eucalypts are 

 odorous trees, nearly all Australian ; there are very few in the Indian 

 Archipelago. The leaves are frequently variable in form, according 

 to the age of the tree ; the lower opposite and the upper often 

 alternate. The flowers are axillary, solitary or in cymes. In E. 

 Lehmanni, type of a genus Symphyomyrtus, the contracted inflo- 



