51 



-aestivation. The aestivation of the sepals and petals is : 



crumpled, when they are irregularly folded ; 



valvate, when ..their margins are in contact and there 

 is no overlapping. When the margins, besides 

 being in contact, are turned straight inwards it 

 is valvate-induplicate, and when the margins are 

 involute it is valvate -involute ; 



imbricate, when their margins overlap and at least 

 one of each whorl has both margins covered ; 



contorted, when every one of the same whorl has one 

 margin covered and one margin uncovered. Assum 

 ing that the observer stands outside the whorl and 

 therefore behind the sepals, or petals, as the case 

 may be, when the right-hand margin of each is un- 

 covered they are said to overlap to the right and 

 when the left-hand margin of each is uncovered to 

 overlap to the left. 



In addition to overlapping the leaves may be twisted, 

 and this twisting may, or may not, be in the same 

 direction as the overlap. 



plaited, or plicate, when they are in longitudinal 

 folds. 



For illustrations see Figs. 15 19, Plate X. 



49. As already noted a normal characters 



.-stamen consists of a swollen head (the anther) on a stalk of Stamens, 

 (the filament). 



A typical anther consists of two longitudinal halves, or 

 lobes, called thecae, each of which, at least when young, contains 

 2 cells, or chambers. These cells contain the pollen and are 

 called the pollen-sacs. When mature the anther opens (i.e., 

 dehisces) and allows the pollen to escape. Each theca com- 

 monly opens by a longitudinal slit in such a way that one slit 

 opens at once into both sacs, each theca thus appearing to be 

 one-celled. The two sacs in each theca also are sometimes 

 confluent before dehiscence. In a few cases the anther has only 

 one cell. According to the number of cells it is uni-, bi-, or 

 quadri-locular. The anthers sometimes dehisce by means of 

 small holes (pores) and sometimes by valves. That portion of 

 the filament which runs up between the anther-lobes is called 

 the connective. The filament is sometimes wanting and then 

 the anther is said to be sessile. Sometimes the anther is not 

 developed and sir.ch an imperfect stamen is called a siaminodium 



f)T staminode. 



E 2 



