PROTEACEJE. 401 



All these plants have certain constant characters in common : a 

 tetramerous perianth, valvate in the bud ; four stamens superposed 

 to the perianth-leaves ; a free gynaeceum with a one-celled ovary ; 

 a dry fruit; an exalbuminous seed with its radicle inferior. The 

 variable characters are : the conformation of the perianth (regular 

 or irregular) ; the level of the insertion of the stamens ; the union 

 or freedom of the anthers ; the presence or absence of a disk, and, 

 if present, the extent to which it surrounds the gynseceum ; the 

 form of the style, especially its stigmatiferous portion ; the number 

 of ovules, their direction and form (anatropous or orthotropous) ; 

 the consistence of the pericarp, which may be dry or fleshy, dehis- 

 cent or indehiscent. It is on these variable characters that the 

 subdivisions of the order have been based. Since the days of 

 R. Brown it has been divided into two grand sections in the first 

 place. The fruit is indehiscent in the one {Nacameniacea) ; dehis- 

 cent in the other {Full ic id ares). But this character will sometimes 

 unfortunately separate widely two genera that would be considered 

 identical if the flowers alone were examined. Thus we may cite 

 A n drift et alum, possessing the flower of Boupala, without any ap- 

 preciable difference ; but as the follicle is not dehiscent in the 

 former, it is quite removed from the latter in the classifications in 

 vogue. Strangea, again, said to have quite the habit and inflo- 

 rescence of Persoonia, has dehiscent fruits, and cannot come in the 

 same tribe. Helicia, so similar in flowers and vegetative organs to 

 both Boupala and KnigJdia, has been relegated by several authors to 

 quite another series. Moreover, in collections are found numerous 

 examples possessing only the flowers ; there is a fair number of 

 genera, more or less contested, of which the ripe fruit is unknown, 

 and whose place it is impossible to fix, if we are to make this feature 

 of dehiscence or indehiscence of primary importance. Hence we 

 base our divisions first on the characters of the flowers. In the 

 series thus established we look for the number of seeds. This 

 enables us to distinguish in Embothriece, for instance, two secondary 

 groups : Euembothriece, which has at least four seeds ; and Grevillea, 

 which has at most two. Among these last the ovules may be 

 descending and orthotropous, or ascending and anatropous ; in this 

 way we can distinguish the genera Bettendena, Bon pal a, Lambertia, 

 &c, from Helicia and Xylomelum, which have nearly the same 

 flower. We next take into account the regularity of the perianth, 



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