AZOLLA AND SALVINIA. 



555 



Leaves opposite, so close together as to become imbricated, espe- 

 cially the lower membranous ones, entire, obliquely ascending, thick, 

 fleshy, outer surface covered with stout whitish papillae of a single 

 somewhat conical cell, the oldest ones rather the smallest, upper 

 ones more or less trapeziform. Under ones quite membranous, hya- 

 line, larger, nearly reniform, with a tendency, especially in the 

 young ones, to have the points incurved ; these are composed of a 

 single layer of cellular tissue. 



The growing points especially, present a number of minute con- 

 fervoid filaments, the assumed male organs, which at certain periods 

 may be seen passing into the foramen, the ovula becoming resolved 

 into their component cells within the cavity of that body. 



Organs of reproduction in pairs, attached to the stem and branch - 



one above the other, concealed in a membrauous involucrum. 

 Ovula atropous, oblong-ovate, with a conspicuous foramen and nu- 

 cleus, around the base of which are cellular protuberances. 



Capsules of each pair either difform — in which case the lowest 

 one is oblong-ovate, the upper globose — or both of either kind, ge- 

 nerally perhaps the globose, presenting at the apex the brown re- 

 mains of the foramen* and still enclosed in the involucrum. Upper 

 half generally tinged with red. 



The oblong -ovate capsule opens by circumcision ; with the apex se- 

 parate the conteuts, which consist of a large yellow sac contained in 

 a fine membrane, the remains of the nucleus (or the secondary cap- 

 sule.) The sac is filled with ole.iginous granular fluid, and sur- 

 tnounted by a mass of fi-brous-tissue, by which it adheres slightly to 

 the calyptra ; on the surface of the fibrous tissue are 9 cellular 

 lobes (the three upper the largest), which when pulled away, se- 

 parate with some of the fibrous tissue, and so appear provided with 

 radicles. 



* See also Martius,*;. 74, f, 10, and Meyen f. 23, for the apex of the 

 round capsule containing the pedicelled secondaries. 



M. Meyen indeed says, his figure is a representation of the base of this 

 organ, his common indusium ; but this is probably a mistake. For the 

 mere punctum in the centre is too small an indication of a rather large 

 hilum, and the disposition of the cells and whole appearance is that of 

 the apex. 



