OF PLANTS CALLED COMPOSITE. 317
reduced, the same alternation does not exist, especially in those genera having vertically compressed pericarpia and two aristae, as Spilanthus and Salmea.
The absence of " discus epigynus" in Boopidece is a necessary consequence of the accretion of the base of the style with the tube of the corolla. It seems to me, how- ever, that a modification of the same organ may be traced in the five thickened areolae observable within and near the base of the tube formed by the filaments in Acicarpha sjjci- thdata ; and much more distinctly in the same situation in Boopis balsamitifolia, where they have the appearance of five adnate fleshy bodies alternating with the filaments.
This apparent decomposition of the glandular disk in Boopidece, compared with its state in Composite, as well as its transposition and the alternation of its parts with the stamina, seem to give some additional support to the con- jecture I have formerly hazarded in the paper on Protectees, published in the Society's Transactions (vol. x, p. 159 1 ); namely, that in several families — for the hypothesis is not meant to be extended to all — this part, even in its cui simplest state, may be considered as formed of a series of modified stamina : Or, merely to state the facts from which the conjecture originates, that there are certain families in some of whose genera this organ exists in its simplest form, that of an undivided fleshy ring ; while in other genera of the same families it consists of several distinct bodies alter- nating with the stamina, and in some cases putting on the appearance of barren filaments.
This hypothesis is chiefly applicable to families in which the number of stamina is equal to the divisions of one floral envelope only, the nectarium being supposed to be formed of the second series : but it receives its principal support from Scitaminece, 2 where the glandular bodies belong actually to the same series with the perfect stamen.
I am aware at the same time of several objections to its generalisation. Thus, the nectarium or glandular disk exists in families where, though the stamina are definite,
1 [Ante, p. 133.]
2 See Flinders's Voyage to Terra Australis, ii. p. 574 [vol. i, p. 49].
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