OF PLANTS CALLED COMPOSITE. 279
in any natural family may with some confidence be pre- dicted by an examination of those genera where the number is complete.
Wherever the separation of sexes takes place, it may be assumed that the female flower is the more perfect pro- duction. And if this be admitted, where both sexes exist in the same simple spike the female should be found at its base, or where expansion commences, which is almost uniformly the case. For the same reason, in the trifid or trichotomous inflorescence, the female should be placed in the centre, which is also generally the fact. 1
This connexion between precocity and perfection of deve- lopment is even more constant than the order of expansion in certain forms of inflorescence; as it is found to extend to several of the exceptions to this order.
Thus in the apparently simple spike of Poterium, where the order of expansion is descendent, the female flowers occupy the upper part of the spike; and this relation also [99 exists in the more compound inflorescence of Ricinus, Siphonia, and Celtis, in which the order of expansion is equally inverted.
It may seem rather paradoxical to select Euphorbia as an example of the same relation ; this genus being considered by Linnaeus, and the greater part of the botanists who have adopted his system, as having a dodecandrous hermaphro- dite flower. We have already, however, I believe, sufficient evidence that this supposed hermaphrodite flower is in reality formed of several monandrous male flowers surround- ing a single female. 2
1 To this order the most remarkable exception occurs in Begonia, in which the male flowers are centra!, and expand long before the lateral female flowers.
2 To the arguments I have adduced (in my Remarks on the Botany of New Holland [vol. i, p. 28]) in support of this opinion, I am now enabled to add the more direct proof derived from certain species of Euphorbia itself, in which the female flower is furnished with a manifest calyx. I have formerly observed, that in a few cases the footstalk of the ovarium is dilated and obscurely lobed at top ; but in the species now referred to it terminates in three distinct and equal lobes of considerable length, and which being regularly opposite to the ceils of the capsule may be compared to the three outer foliola of the periau- thium of Phyllanthus, between which and the cells of the capsule the same rela- tion exists. This calyx is most remarkable in an undescribed species of Euphorbia from the coast of Patagonia, in the Herbarium of Sir Joseph Banks; but it is observable, though less distinct, in E. punicea and several other species.
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