In some rain-dispersed plants of otherwise polysymmetric groups (with disymmetric gynoecium) the fruits (and the gynoecium at anthesis) are pronouncedly monosymmetric, such as Tiarella and some Chrysosplenium species of Saxifragaceae.
Tiarella and some Chrysosplenium species have a monosymmetric gynoecium giving rise to fruits with rain dispersal (see above).
Splash-cup dispersal mechanism in Chrysosplenium and Mitella.
Table 2 Changing expression of floral monosymmetry during development Early development Anthesis Monosymmetry strongest in early development Arabidopsis + - Monosymmetry strongest at anthesis (in species-rich families) Fabaceae + ++ Veronicaceae + ++ Asteraceae/(Cichorioideae) -/(+) ++ Orchidaceae + ++ Monosymmetry strongest in fruit Tiarella + + Chrysosplenium sp.
Chrysosplenium can be found in such habitats today and is particularly associated with damp, shady areas and stream banks within forests, especially gymnosperm-dominated forests (Hara, 1957; Ohwi, 1965; Yuzepchuk, 1971; Savile, 1975; Hickman, 1993).
No evidence was noted in this study of a compound-leafed ancestry for Saxifraga, Chrysosplenium, or Gunnera.
Paleobotanical considerations of eudicot origins need to incorporate a search image of small, low-rank herbaceous leaves like those of the subgenus Ostenigunnera and the genera Chrysosplenium and Saxifraga.