THE MICROSPORANGIUM 39 



Formation of sterile septa is also known in a few other plants. 

 Caldwell (1899) reports that in Lemna the archesporial tissue orig- 

 inally comprises a single mass of cells. After the usual wall layers 

 have been cut off, a plate of sterile cells divides this mass into two 

 and then into four. In Limnophyton (Johri, 1935) and Ranunculus 

 (Singh, 1936) a cross section of the young anther shows an oval or 

 somewhat dumbbell-shaped outline with a plate of archesporial 

 cells on each side. Both of these become partitioned by the ap- 

 pearance of a sterile septum resulting in the usual tetralocular con- 

 dition. In Quamoclit (Fedortschuk, 1932) there is a single row of 

 sporogenous cells in each lobe of the anther but one or two of these 

 fail to keep pace with the others and become nonfunctional. These 

 give rise to sterile partitions separating the loculus into two or three 

 parts. 



In some plants there are fewer than four groups of sporogenous 

 cells. In the family Malvaceae (Stenar, 1925) the anthers are uni- 

 formly bisporangiate and the two loculi eventually fuse to form a 

 single loculus. In Elodea (Wylie, 1904), Styphelia (Brough, 1924), 

 Circaeaster (Junell, 1931), Phoradendron (Billings, 1932), Wolffia 

 (Gupta, 1935), and Moringa (Puri, 1941) also, there are two micro- 

 sporangia which may later become confluent by the breaking down 

 of the intervening cell layers. The anthers of Naias (Campbell, 

 1897) are said to be unilocular, but the developmental stages have 

 not been traced satisfactorily. In Vallisneria (Witmer, 1937) there 

 are all gradations from a unilocular to a tetralocular condition. 

 Typically two loculi are formed, owing to the appearance of a sterile 

 septum in the sporogenous tissue, but sometimes the septum is 

 incomplete, resulting in a unilocular condition, and frequently each 

 of the two loculi becomes bisected so as to form four loculi. 



The stamens of Piper betle (Johnson, 1910) are peculiar in that the 

 number of microsporangia in an anther may be four, three, two, or 

 one, and it remains constant from the time of initiation of the 

 sporangia to the maturation of the anther. There is no secondary 

 fusion of the sporogenous tissue. 



In Korthalsella (Stevenson, 1934; Rutishauser, 1935) there are 

 three stamens, each of which consists of two microsporangia, but 

 since all the anthers fuse to form a synandrium, a cross section of 

 the flower shows six microsporangia arranged in a ring. At matur- 



