CRYPTOGAMS AND PHENOGAMS 



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Fig. 381. — Japanese Cycad {t ycu6 rtvoluia, Cyead Family, Cycadacew) . 

 1, seed-bearing plant. 2, macrosporangial leaf or carpel showing the 

 naked ovules (macrosporangia) near its base. 3, microsporangial leaf, 

 or stamen, showing the numerous microsporangia (anthers) on its lower 

 face. (Wossidlo.) — Tree growing about 3 m. tall; fruit densely hairy. 

 Native home, Japan; commonly cultivated as "sago-palm." 



vided with numerous swimming-hairs. One of these fertilizes the 

 egg-cell. After fertilization a seed is formed, an abundance of extra 

 food being stored about the single embryo. The sporophyte as it 

 develops becomes, as we have seen, singularly like a tree-fern and 

 at the same time so closely resembles a Metroxylon as to be called 

 by florists a "sago-palm." While we must of course regard this 

 outward resemblance as more or less superficial, it gains significance 

 from the presence of much deeper resemblances which have led 

 botanists to regard the Cycad-type as a connecting link between 

 the fern and the angiosperm. 



As already shown, the main difference between a gymnosperm 

 and an angiosperm is that the latter_ incases its macrosporangia in 

 carpellary leaves. Fertilization is accomplished, however, as before 

 by means of a pollen-tube, which, starting from the stigma, has 

 simply a longer road to travel before its tip reaches the egg-cell. 

 Moisture to enable the microspore to germinate is afforded by a 

 stigma, while food for the tubular cell is supplied by the tissues 

 along its route. The parts concerned in angiospermic fertilization 

 are shown in Fig. 382. When germinating, the pollen-cell produces 

 two nuclei, one of which represents the vegetative part of the male 



