130 ACADEMIC BOTANV. 



tion ; yet they produce perfect seeds, which produce perfect plants, 

 continuing the generation. Fertilization is the rule among phan- 

 erogams. These plants being dioecious, however, may often be too 

 widely separated for the pollen of one to reach the stigma of the 

 other; and this parthenogenesis is perhaps — with all respect to Mr. 

 Darwin — a "survival of the fittest;" the fittest being the mother, who 

 has the chief, often the whole care of her young. 



295. Many solf-pollinating flowers require foreign aid, from insects, 

 the wind, or other agencies. Tlie ten stamens of the Kalmia are con- 

 fined by their anthers in as man}' little pouches in the corolla. There 

 they remain, incapable of extricating themselves, until released by 

 some insect, or the wind, or a blow of some sort ; then they spring up 

 towards the pistil mechanically, lilce a bow unstrung, and their pollen 

 is shod upon it. The Barberry stamens lie out against the petals. 

 The sun's heat arouses them ; or an insect, foraging for honey in the 

 nectaries of the petals, touches the irritable base of the stamen, which 

 immediately springs up by spontaneous action and projects its pollen 

 on the stigma. Here, and in the Kalmia, the insect bears off pollen 

 to another flower, thus securing foreign pollination also. In the 

 Milkwort (Fig. 185), which is self-pollinating, special provision to 

 secure foreign fertilization also is made in the viscid disk behind the 

 stigma, to which pollen brought by an insect will cohere. 



296. Foreigrn Pollination is the prevailing habit through- 

 out the vegetal kingdom. In monoecious plants the sta- 

 mens and pistils of flowers on the same plant usually ripen 

 at different times. 



297. This rule governs the greater number of mono- 

 clinous flowers also ; they are furnished with both organs, 

 as a reserve, apparently, in case of the failure of pollen 

 from distant flowers. At any rate, we are taught, from 

 the first hint at two sexes in the Diatoms (44), tiiat for- 

 eign pollination gives the best results, almost invari- 

 ably. 



298. Dichogamy. — Monoclinous flowers with pistils and stamens 

 ripening at different times are termed Dickogamous, or separate- 

 wedded (Gr. dike, separate) When the pistils ripen first, as in the 

 Aristolochia (Fig. 186), the fiower is Froterogynous ({jr. protos, 

 first). When the stamens ripen first, as in the Sage (Pig. 187), the 

 flower is Proierandrous. The proterogynous flower is, therefore, 

 first female and then male ; the proterandrous flower first male and 

 then female. 



299. Homomorphous and Heteromnrphous flowers. — In most flowers 

 the stamens and pistils have relatively the same length and position 

 towards each other in the same species ; they are therefore termed 

 Homomorphous (Gr. homo, similar; morphe, form). Sometimes, 

 however, we find Heteromorphous flowers (Gr. heteros, another, un- 

 like), — that is, with stamens and pistils different in length and posi- 



