142 MORPHOLOGY 



plants like Globa bulbifera (see fig. 23) and other 

 species of Globa, rasun, murga, Agave Cantula (see 

 fig. 22), Furcraa gigantea, aerial bulbils separate 

 from the inflorescence, fall to the ground, and give 

 rise to new plants. Several species of Dioscorea 

 (chupri-aloo) (see fig. 24) produce little tubers, or 

 corm - like bodies, on their climbing stems, which, 

 separating from the stems, fall to the ground, and 

 give rise to new plants. The principle of vegetative 

 reproduction has been imitated in gardening and 

 farming. Thus propagation of plants by CUTTING, 



LAYERING, BUDDING, GRAFTING, &C. , is nothing morC 



than artificial imitation of nature. 



Sexual reproduction, as already explained, consists 

 in the production of new plants from seeds which are 

 the results of the union of two sexual cells, male and 

 female. In Phanerogamia and the higher Crypto- 

 gamia, where the sexual cells are differentiated, the 

 process of their union is known as fertilization. 

 In many lower Cryptogamia the sexual cells are not 

 differentiated, and the union of these undifferentiated 

 sexual cells is known as conjugation. The product 

 of fertilization is known as oospore, and that of con- 

 jugation as ZYGOSPORE. The Oospore and Zygospore . 

 are both known by the name of zyote. In rare cases 

 the female cell or oosphere alone, without fusion with 

 the male cell, develops into an embryo. This is 

 known as parthenogenesis. 



Asexual reproduction is a means of propagation by 

 single cells, which are specially formed for the pur- 

 pose, and known by the name of spores. , As this 

 method of reproduction is confined to Cryptogamia, 

 readers are referred to a detailed description of it in 

 the part devoted to Cryptogamia. Asexual repro- 

 duction is really a variety of vegetative reproduction, 



