THE MICROSPORANGIUM 



31 



manyam, 1948) in which the fibrous thickening are absent but the 

 walls of the epidermal cells undergo a general cutinization and 

 lignification over the entire surface. Oryza (Juliano and Aldama, 

 1937), Ditepalanthus (Fagerlind, 1938), and Balanophora (Fager- 

 lind, 1945) are peculiar in that the parietal layers, one or two in 

 number, become crushed and disorganized during the development 

 of the anther so that a fibrous layer is absent and the epidermis 

 abuts directly on the tapetum. 1 



A 



Fig. 25. Development of anther of Erica hirtiflora. A, B, l.s. young stamens, 

 showing gradual inversion of anther. C, l.s. stamen at spore mother cell stage, 

 showing almost complete inversion of anther, so that its lower end comes to lie 

 toward the upper side. (After Matthews and Taylor, 1926.) 



Next to the endothecium there are usually one to three "middle" 

 layers. As a rule, all of them become flattened and crushed at the 

 time of the meiotic divisions in the microspore mother cells, but 

 there are a few exceptions. In Holoptelea (Capoor, 19376) there are 

 three to four middle layers, of which the outermost persists for a 

 long time. In Ranunculus (Singh, 1936) there are two middle 

 layers, of which the inner soon disappears but the outer persists; 



1 In Styphelia (Brough, 1924), Arceuthobium (Pisek, 1924) and some members 

 of the Ericales it is the epidermis which is said to develop fibrous thickenings and 

 function as an endothecium, but this deserves confirmation. 



