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Show 138 HETEROSTYLED TRIMORPHIC PLANTS. CHAP. IV. are considered, there are :five distinct sets of males. Two of the three hermaphrodites must coexist, and pollen must be carried by insects reciprocally from one to the other, in order that either of the two should be fully fertile; but unless all three forms coexist, two sets of stamens will be wasted, and the organisation of the species, as a whole, will be incomplete. On the other hand, when all three hermaphrodites coexist, and pollen is carried from one to the other, the scheme is perfect; there is no waste of pollen and no false coadaptation. In short, nature has ordained a most complex marriage-arrangement, namely a triple union between three hermaphrodites,-each hermaphrodite being in its female organ quite distinct from the other two hermaphrodites and partially distinct in its male organs, and each furnished with two sets of males. The three forms may be conveniently called, from the unequal lengths of their pistils, the long-styled, midstyled, and short-styled. The stamens also are of unequal lengths, and these may be called the longest, mid-length, and shortest. Two sets of stamens of different length are found in each form.. The existence of the three forms was first observed by Vaucher, *and subsequently more carefully by Wirtgen; but these botanists, not being guided by any theory or even suspicion of their functional differences, did not perceive some of the most curious points of difference in their structure. I will first briefly describe the three forms by the aid of the accompanying diagram, which shows the flowers, six times magnified, in their natural position, with their petals and calyx on the near side removed. * 'Hist. Phvs. des Plantes d'Europe,' tom.~ ii. 1841, p. 371. Wirtgen,'' Ueber Lythrum salicaria und dessen Formen," 'Verband. des naturhist. Vereins fiir preuss. Rheinl.' 5. J ahrgang, 1848, S. 7. CHAP. IV. Long- 6tyletl. Mid-styled. '' Shortstyled. LYTHRUM SALICARIA. 139 Fig. 10. Diagram of the flowers of the three forms of Lythrum ~alicaria, in thei.r n~tural position, with the petals and calyx removed on the near s1de: enlarged SIX tm1es. The dotted lines with the arrows show the directions in which pollen must be carried to each stigma to ensure full fertility. |