296 THE CROSSING OF FLOWERS. 



phrodite flowers exclusively. Although this group is not so comprehensive as it 

 was thought to be in the time of Linnaeus, it is nevertheless the most important, 

 and includes more than a third of all the Phanerogams. The Al^pinia, Lilac, 

 Cornel, Gagea, Spurge Laurel, Flowering Rush, Phytolacca, Agrimony, Lime, 

 Anemone, Bitter-cress, Baobab, and Melaleuca, all figured on pp. 289, 292, 293, may 

 be mentioned as examples. 



Close to these comes a second group of species which bear pseudo-hermaphrodite 

 female flowers as well as truly hermaphrodite flowers, as, for example, Oxyria 

 digyna and Geranium lucidv/m. 



The third group includes those species whose individuals develop both true 

 hermaphrodite flowers and those which appear to be so, but are really pseudo- 

 hermaphrodite male flowers. Though instances of the second group are rare, the 

 third comprises hundreds of species from widely-difierent families. Special instances 

 are furnished by the North American Shrubby Trefoil (Ptelea trifoliata), the 

 common Bistort {Polygonwm Bistorta), the Horse -Chestnuts {JEscuhis, Pavia), 

 some Aralias (e.g. Aralia nudicauUs), several species of Bed-straw and Woodrufl" 

 (e.g. Galium Gruciata, Asperula taurina), and many Umbelliferse. In the last- 

 named the arrangement and distribution of the two kinds of flowers is quite deter- 

 minate for each genus, and has the closest connection with the processes of pollen- 

 transfer. In Anthriscus the umbellate heads of the central umbel contain for the 

 most part true hermaphrodite flowers surrounded by a few pseudo-hermaphrodite 

 male flowers. The heads of the lateral umbels, however, are composed entirely of 

 these staminate flowers. In Caucalis the central umbellate heads consist exclusively 

 of pseudo-hermaphrodite male flowers, while the other heads are formed of 2 true 

 hermaphrodite flowers and 4-7 pseudo-hermaphrodite male flowers. In Astrantia 

 the large central umbels contain 12 hermaphrodite flowers surrounded by a few 

 pseudo-hermaphrodite male flowers, but the lateral, smaller umbels contain the latter 

 only. Athavianta cretensis, GhcerophylluTn aromaticum and Meum Mutellina have 

 in all their umbels a central hermaphrodite flower surrounded by staminate flowers 

 {i.e. male pseudo-hermaphrodites), and these in turn are surrounded by true 

 hermaphrodite flowers. All the umbels of Ghcerophyllum Gicutaria and Laser- 

 pitiwm latifolium, contain short-stalked pseudo - hermaphrodite male flowers 

 surrounded by long-stalked truly hermaphrodite flowers. In the centre of all the 

 umbels of Turgenia latifolia are 6-9 pseudo-hermaphrodite flowers which do not 

 radiate, and 6-8 true hermaphrodite flowers, ray-like on the circumference ; whilst 

 in Sanicula europ(Ba there are three central hermaphrodite flowers in each umbel 

 surrounded by 8-10 pseudo-hermaphrodite male flowers. 



In the fourth group each plant bears both truly hemaphrodite and truly pistil- 

 late flowers. A large number of Composites come under this heading, of which 

 the Asters may be taken as a type {Aster, Bellidiastrum, Stenactis, Solidago, 

 Bwpthalmum, Inula, Arnica, Boronicum, &c.). The tubular florets of the disc are 

 truly hermaphrodite in each capitulum, while the tongue-shaped ray-florets are 

 truly pistillate. This division of the sexes also occurs in other Compositse, of which 



