The inner or upper portion of the anther-leaf is that which is most intimately concerned in the formation of pollen; it comparatively rarely (query ever) happens that the back or lower surface of the antheral leaf is specially devoted to the formation of pollen. On the other hand, in cases like those of the common houseleek, where we meet with petaloid organs combining the attributes of anthers and of carpels, we find the inner layers devoted to the production of pollen, the outer to the formation of ovules.
That the pollen-lobes are not to be taken as halves of a staminal leaf, but rather as specialised portions of it, not necessarily occupying half its surface, is shown also in the case of double-flowered Malvaceæ, in which the stamens are frequently partly petal-like, partly divided into numerous separate filaments, each bearing a one-, or it may be even a two-lobed anther. This circumstance is confirmatory of the opinion held by Payer, Duchartre, Dickson, and other organogenists, as to the compound nature of the stamens in these plants. The stamens are here analogues not of a simple entire leaf, but of a lobed, digitate, or compound leaf, each subdivision bearing its separate anther. On this subject the reader may consult M. Müller's paper on the anther of Jatropha Pohliana, &c., referred to at page 255.
[310] See C. Morren, "On Spur-shaped Nectarines," &c., 'Ann. Nat. Hist.,' March, 1841, p. 1. tab. 11.
[311] Karsten, 'Flor. Columb. Spec.,' tab. xxix.
[312] See Dickson, "On Diplostemonous Flowers," 'Trans. Bot. Soc. Edin.,' vol. viii, p. 100; and on the Andrœcium of Mentzelia, &c., in Seemann's 'Journal of Botany,' vol. iii, p. 209, and vol. iv (1866) p. 273 (Potentilla, &c.).
[313] See Baillon, 'Adansonia,' iii, p. 351, tab. 12, Sinapis.
[314] 'Bull. Acad. Belg.,' xvii, part i, p. 516, c. tab., and 'Lobelia,' p. 83.
[315] Cited in 'Bull. Soc. Bot. France,' xiv, p. 253 ('Rev. Bibl.').
[316] 'Bull. Soc. Bot. Fr.,' 1858, p. 331.
[317] 'Mem. Legum.,' p. 44.