Treviranus[198] says that the flowers of _Hippuris_ and _Callitriche_ are apt to be hermaphrodite in summer, but female only at a later period.
For further remarks on this subject, see sections relating to suppression of stamens and pistils.
=Change from unisexuality to hermaphroditism.=--This occurrence depends on one of two causes, either organs are developed (stamens or pistils as the case may be), which are habitually absent in the particular flower; or some of the stamens may be more or less completely converted into or replaced by pistils, or _vice versâ_.
The first condition is the opposite of suppression; it is, as it were, a restoration of symmetry, and might be included under the head of regular peloria, inasmuch as certain organs which habitually undergo suppression at a certain stage in their development, by exception, go on growing, and produce a perfect, instead of an imperfect flower. In teratological records it is not always stated clearly to which of the two above-named causes the unusual hermaphroditism belongs, though it is generally easy to ascertain this point. Very many, perhaps all, diclinous flowers may, under certain conditions, become perfect, at least structurally. I have myself seen hermaphrodite flowers in _Cucurbita_,[199] _Mercurialis_, _Cannabis_, _Zea Mays_, and _Aucuba japonica_, as well as in many _Restiaceæ_, notably _Cannamois virgata_ and _Lepyrodia hermaphrodita_. _Spinacia oleracea_, _Rhodiola rosea_, _Cachrys taurica_, and _Empetrum nigrum_ are also occasionally hermaphrodite.
Gubler[200] alludes to a similar occurrence in _Pistacia Lentiscus_, wherein, however, he adds that there was a deficiency of pollen in the flowers.
Schnizlein[201] observed hermaphrodite flowers in the beech, _Fagus sylvatica_, the ovaries being smaller than usual, and the stamens epigynous.
Baillon[202] enumerates the following _Euphorbiaceæ_ as having exceptionally produced hermaphrodite flowers, _Crozophora tinctoria_, _Suregada_ sp., _Phyllanthus longifolius_, _Breynia_ sp., _Philyra brasiliensis_, _Ricinus communis_, _Conceveiba macrophylla_, _Cluytia semperflorens_, _Wall_, non _Roxb_. _Mercurialis annua_ and _Cleistanthus polystachyus_.
In some of these cases the hermaphroditism is due to the development of anthers on the usually barren staminodes, though, in other cases, the stamens would seem to be separate, independent formations, as they do not occupy the same relative position that the ordinary stamens would do if developed.[203]
