DISTRIBUTION OF SEXES 



31 



and hermaphrodite-female, that is, gynodioecism is united with gynomonoecism : 

 Female Pleogamy. 



To this group belong: — Hepatica, species of Ranunculus, most of the German 

 species of Dianthus, many Lychnideae, almost all Alsineae, many species of 

 Geranium, Potentilla, Epilobium, also Ribes Grossularia, Saxifraga oppositifolia, 

 Sherardia arvensis, most Dipsacaceae, Convolvulus, Anchusa, Echium, species of 

 Verbascum and Digitalis, most German Labiatae, species of Plantago, Polygonum 

 amphibium, and others. 



Group 2. — In many stocks that are fundamentally hermaphrodite some of the 

 carpels degenerate, in others they all degenerate. The individuals are therefore 

 again of three kinds : Hermaphrodite, male, and hermaphrodite-male, i. e. andro- 

 dioecism is united with andromonoecism : Male Pleogamy. 



To this group belong: — Pulsatilla alpina, Dryas octopetala; Geum urbanum, 

 rivale, reptans, and montanum; many species of Rubus, Asperula taurina, 

 Chenopodium glaucum and vulvaria, Veratrum album. 



Group 3. — In many stocks that are fundamentally hermaphrodite, the stamens 

 degenerate in all or some flowers. Similarly, in other hermaphrodite stocks the 

 carpels degenerate in all or some of the flowers. In yet other stocks degeneration 

 does not usually occiu", though it occasionally affects the stamens and carpels of 

 difierent flowers on the same plant. We have here, therefore, andromonoecism, 

 androdioecism united with gynomonoecism, and gynodioecism, so that five difierent 

 series of individuals commonly result, while to these may sometimes be added a 

 supplementary series of trimonoecious individuals. By the increasing suppression 

 of hermaphrodite flowers and hermaphrodite plants, there appears in this group 

 a tendency towards the formation of purely dioecious plants, but three stages 

 may still be distinguished : 



1. TTie hermaphrodite forms predominate markedly, while the pleogamous forms 

 are very common. 



Euonymus europaeus. Mostly hermaphrodite. Among several thousand 

 shrubs will be found only 1-3 purely unisexual individuals. Gynomonoecism 

 and andromonoecism are here and there more common. 



Fragaria vesca. Mostly hermaphrodite. The pleogamous forms are some- 

 times entirely wanting. They occur in approximately equal numbers. 



F. collina. Purely hermaphrodite forms nearly always predominate. Pleo- 

 gamous forms are always rather more abundant than in the preceding species. 



Plantago media. Mostly hermaphrodite. Female-pleogamous forms, when 

 present, amount to 2-3 %. Male-pleogamous forms are still scarcer. 



Swertia perennis. Occasionally gynomonoecious, rarely gynodioecious, andro- 

 monoecious, or androdioecious. 



2. Hermaphrodite forms less dominant, while pleogamous forms appear somewhat 

 more frequently. Among the latter either female or male may predominate,, or they may 

 occur in approximately equal numbers. 



(a) Female Forms predominate. 

 Geranium sylvaticum. Female-pleogamous up to 25 %. Male forms scarce. 



