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 OF CENTRAL AFRICA. 293

relations in the reduced series of pistilla should have sug- gested the opinion, that in a conij)lete flower, whose [2:57 parts are definite, the number of stamina and also of })istilla is equal to that of the divisions of the calyx and corolla united in Dicotyledones, and of both scries of the perian- thium in Monocotyledones.

This assumed complete number of stamina is actually the prevailing number in Monocotyledones ; and though in Dicotyledones less frequent than what may be termed the symmetrical number, or that in which all the series are equal, is still found in decandrous and octandrous genera, and in the greater part of Leguminos3c. The tendency to the production of the complete number, where the symmetrical really exists, is manifested in genera belonging or rchited to those pentandrous families in which the stamina arc opposite to the divisions of the corolla, as by Samohis related to Prinudaceoe, and by Bscobotrys, having an analo- gous relation to Myrsinese ; for in both these genera, five additional imperfect stamina arc found alternating with the fertile, and consequently occupying the place of the only stamina existing in most pentandrous families. Indications of this number may also be said to exist in the divisions of the hypogynous disk of many pentandrous orders.

with respect to the Pistilla, the com])lete number is equally rare in both the primary divisions of phacnogamous plants. In iMonocotyledones the symmetrical nund)cr is very general, while it is much less frequent in Dicotyledones, in which there is commonly a still further reduction.

Where the number of Pistilla in Dicotyledones is reduced to two, in a flower in wdiich both calyx and corolla are present and their division quinary, one of these pistilla is placed within a division of the calyx, the other opposite to a petal or segment of the corolla. In other words, the addition to the solitary pistillum, (which is constantly an- terior or exterior), is posterior or interior. This is the general position of the component parts of a bilocular ovarium, or an ovarium having two parietal placentae ; and in flowers whose division is quinary, I can recollect no other exceptions to it than in some genera of Dilleniaccce.

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