464 



ANGIOSPERMAE—DICOTYLEDONES 



even in the third type (C), where hermaphrodite and female flowers are associated, 

 for here the primary umbels possess but few male flowers, while in those which 

 bloom last scarcely any others are present. 



Something has already been said about the geitonogamy that so frequently 

 takes place among Umbelliferae (Vol. I, pp. 41-2). Kerner describes some very 

 diverse arrangements of the kind ('Nat. Hist. PI.,' Eng. Ed. i, II, pp. 323-5). In 

 the crowded capitula of Eryngium and Hacquetia, when the filaments elongate 

 their pollen -covered anthers come into contact with the mature stigmas of 

 neighbouring flowers, in consequence of the divergence of the styles. In 

 Sanicula, Astrantia, and Laserpitium, there is a deviation from this form of 

 geitonogamy owing to the fact that pollen flowers as well as hermaphrodite ones 

 are present ; but here again the same thing happens, because the elongating 

 styles bend over and entangle themselves with adjacent flowers, so that their 

 stigmas can take up pollen. The converse is true for Pachypleurum, where 

 the stamens ultimately radiate in an almost stellate manner, and touch the mature 

 stigmas of neighbouring flowers. The relations are similar in the case of Siler ; 

 while in Athamanta, Meum, and Chaerophyllum, hermaphrodite and pollen flowers 

 are associated. After the stamens of the former have dehisced and fallen off, the 

 pollen flowers ripen their anthers, and drop their pollen upon the still receptive 

 stigmas of the originally hermaphrodite flowers. (Cf. Fig. 155 B.) 



For Anthriscus, Foeniculum, Coriandrum, Slum, and Ferulago, Kerner describe.s 

 inflorescences of two kinds. The umbels that blossom first mostly contain her- 

 maphrodite flowers, with a few scattered pollen flowers, while those which do so later 

 contain only the latter kind. After the stamens of the protandrous hermaphrodite 



flowers have shed their pollen and fallen off', 

 the stigmas become receptive and remain so 

 for some days. Meanwhile the lateral axes 

 bearing male inflorescences continue growing, 

 so that ultimately their umbels lie above the 

 mature stigmas of the hermaphrodite flowers. 

 These stigmas are consequently pollinated by 

 the shower of pollen from the dehiscing anthers 

 of the pollen flowers. 



319. Hydrocotyle L. 



Flowers small, white in colour, and arranged 

 in imperfect umbels ; with exposed nectar. 



1089. H. vulgaris L. (Herm. MiiUer,' Weil. 



Beob.,' I, pp. 302-3; MacLeod, Bot. Jaarb. Do- 



donaea, Ghent, vi, 1894, p. 257 ; Knuth, ' Bl. u. 



Insekt. a. d. nordfr. Ins.,' p. 76 ; Warnstorf, Verb. 



bot. Ver., Berlin, xxxviii, 1896.) — The flowers of 

 this species are extremely inconspicuous, and only 3-5 of them are found in an 

 umbellule. Hermann iNIiiller says they are so feebly protandrous that automatic 



Fig. 156. Hydrocotyle Titilgaris, /.. (after 

 Drude). A. Flower at the close of pollina- 

 tion: the stamens have fallen off, and the styles 

 are erect (X 5) B. Stamens with dehisced 



anthers; stigmas still immature 1 > 5). C. 

 Dried poUen-f^rains swollen by immersion in 

 water (X 400), i, bract. 



