both the character and limits of Polygalea;, which I had proposed, though apparently not altogether satisfied with the description he himself has given of the divisions of the calyx and corolla. The disposition of the parts of the floral envelopes, with reference to the axis of the spike, in Polygalea;, namely, the fifth segment of the calyx being posterior or superior and the fifth petal anterior or inferior, is the usual relation in families the division of whose flower is quinary. This relation is in some cases inverted; one example of which I have formerly pointed out in Lobeliaceae *, as I proposed to limit it, and a similar inversion exists in Le- guminosae. But this class also deviates from the more general arrangement of the parts of the flower with regard to each other. That arrangement consists, as I have long since remarked t, in the regular alternation of the divisions of the proximate organs of the complete flower. To this arrangement, indeed, many exceptions are well known ; and M. De Candolle has given a table of all the possible deviations, but without stating how many of these have actually been observed i. In Leguminosic the deviation from the. assumed regular arrangement consists in the single pistillum being placed opposite to the lower or anterior segment of the calyx. In these two characters, namely, the relation of the calyx and corolla both to the simple pistillum and to the axis of the spike or to the bractea, Legumi- nosse differ from Rosace®, in which the more usual arrangements are found. But in those Rosace®, in which the pistillum is solitary and placed within the anterior petal, its relation to the axis of the spike is the same as that of Leguminosse, in which it is within the anterior division of the calyx. And in all families, whether dicotyledonous or monocotyledonous, this, I believe is uniformly the position of the simple solitary pistillum with regard to the spike or bractea. The frequent reduction of Pistilla, in plants having the other parts of the flower complete in number, must have been generally remarked. But the order in which these abstractions of pistilla take place, or the relations of the reduced series to the other parts of the flower, have, as far as I know, never yet been particularly attended to. It will probably appear singular, that the observation of these relations in the reduced series of pistilla should have suggested the * Flinders's Auslr. 2, p. 559. ' t Prodr. Flor. Nov. Holl. 1, p. 558. t Tlieor. etem. ed. 2. p. 183. opinion, that in a complete flower, whose parts are definite, the number of stamina and also of pistilla is equal to that of the divisions of the calyx and corolla united in Dicotylédones, and of both series of the perianthium in Monocoty- ledones. This assumed complete number of stamina is actually the prevailing number in Monocotyledones ; and though in Dicotylédones 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 Leguminosæ. Thé tendency to the production of the complete number, where the symmetrical really exists, is manifested in genera belonging or related to those pentandrous families in which the stamina are opposite to the divisions of the corolla, as by Samolus related to Primulaceæ, and by Bæo- botrys, having an analogous relation to Myrsineæ ; for in both these genera, five additional imperfect stamina are 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 hÿpogynous disk of many pentandrous orders. With respect to the Pistilla, the complete number is equally rare in both the primary divisions of phænogamous plants. In Monocotyledones, the symmetrical number is very general, while it is much less .frequent in Dicotylédones, in which there is cqmmonly a still farther reduction. Where the number of Pistilla in Dicotylédones is reduced to two, in a flower in which 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 anterior 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 placentæ ; and in flowers whose division is quinary, I can recollect no other exceptions to it, than in some genera of Dilleniaceæ. It is particularly deserving of notice, that the common position of the cells of the bilocular pericarpium with relation to the axis of the spike was well known to Cæsalpinus, who expressly distinguished Cruciferoe from all other bilocular families by their peculiarity in this respect, the loculi in that family being placed right and left, instead of being anterior and posterior*. * Ccesalp. de Plantis> p. 327. cap. xv. et p. 351. cap. liii.
27f 24
To see the actual publication please follow the link above