GEITONOGAMY. 



flowers causes no alteration in the process of fertilization described. We would 

 merely observe that in these plants the hermaphrodite flowers always open earlier 

 than the staminate flowers of the same umbel. Not until the stamens of the 

 hermaphrodite flowers have dehisced and fallen away, whilst their rtigmM 1 

 been waiting for two days for pollen from other plants, do the anthers of the 

 staminate flowers open after growing up far beyond their corollas. Their poll, n 

 then falls on the stigmas of the hermaphrodite flowers. Since there are so many 

 more staminate than hermaphrodite flowers, the success of the process is doubly 

 assured. For example, the umbel of Ghcerophyllum aromaticum (see figs. 294 3 and 

 294 4 ) contains 20 staminate flowers besides one central and 3-5 peripheral herma- 

 phrodite flowers, and therefore to 8-12 functional stigmas there are about 100 

 anthers. Moreover, the hermaphrodite flowers in these Umbelliferra assume such a 

 position at the moment the staminate flowers open that a pollination of their stigi \ 

 by the falling pollen is almost unavoidable (fig. 294 4 ). 



One of the most remarkable instances of geitonogamy is observed in such 

 Umbelliferse as the Beaked Parsley (Anthriscus), Fennel (Foeniculum), Coriander 

 (Coriandrum), Water Parsnip (Sium), and Ferulago. All the species of these 

 genera have two kinds of inflorescence. The umbels which blossom first contain 

 principally true hermaphrodite flowers with a few isolated staminate flowers here 

 and there; the later umbels consist only of staminate flowers. The hermaphrodite 

 flowers which come first are completely protandrous; the anthers, borne on very 

 thin filaments, are brought one after the other to the centre of the flower, where they 

 dehisce and scatter their pollen, and the day following they drop off. After all the 

 five stamens have dropped off the stigmas become mature and receptive. They 

 continue in this condition for two days, and during this period are liable to crossing 

 with the pollen of other plants. Then the umbels bearing only staminate flowers 

 come under consideration. The pedicels which bear them have meanwhile 

 elongated, and have thus obtained such a position that these umbels stand right 

 over the hermaphrodite flowers with their mature stigmas, so that they seem to 

 form an upper story, so to speak, in the inflorescence as a whole. Now, when the 

 anthers in the staminate flowers of this upper story open, and when their walls 

 shrivel up, the pollen is thrown out and falls vertically downwards in minute 

 crumbling masses. The stigmas of the lower, older flowers are thus subjected to a 

 rain of pollen, and it is easy to see that the majority of the stigmas are pollinated 



in this manner. 



The instances of geitonogamy described in Composite and Umbe 

 regarded as typical of what occurs in many representatives of other families. 

 Stellate section of Rubiacese, Caprifoliace*, Cornace*, Scrophularia*e*. I 

 Polygonace*, Liliace*, and Aroide*, whose flowers are crowded together m capi 

 balls, fascicles, spikes, and racemes, repeat these processes sometimes down t 

 minutest detail. For example, the two styles in the protandrous fascicled flowers 

 a Woodruff, Aspernla taurina, elongate, separate from each other and bend 

 just like those of Laserpitium', by this alteration of position they gel 



