138 Plants and their Ways in South Africa 



central placentation," including basal, where the axis is not 

 prolonged. 



Different Kinds of Stamens. Stamens may have long 

 filaments, but in some flowers they are very short. Like the 

 style and the petiole of a leaf, the length is adapted to place 

 the essential part of the organ in a favourable position. When 

 filaments are wanting the anthers are said to be sessile. In 

 S.A. Proteacece, where they seem to be wanting, they have 

 fused with (are adnate to) the perianth lobes. 



Anthers are differently attached to the filaments. In 

 Gladiolus, Lobelia, and some Heaths the filament is joined to the 



dV 



FIG. 129. Section through flower of 

 Barosma crenulata, Hook., after the 

 removal of the petals (magnified) : st, 

 fertile stamens ; sto, barren stamens 

 (staminodes) ; d, lobes of disk. (From 

 FIG. 128. Stamens of Cyanella ca- Edmonds and Marloth's " Elementary 

 pensis, L. Botany for South Africa".) 



base of the anthers (basifixed). In Jasmine the filaments ex- 

 tend between the anthers (adnate) In grasses and in Bulbinella 

 the filaments are so joined to the centre of the anther at the back 

 that they easily swing (versatile). Versatile anthers are fre- 

 quently found where pollen is conveyed from them to the stigmas 

 by wind. The continuation of the filament to which the anther 

 is attached is called the connective. 



Examine anthers in buds. Usually the anther consists of 

 two lobes. On cutting across the anther, each lobe will be 

 seen to contain two pollen sacs or microsporangia. When 

 the pollen grains or microspores are ready to be discharged, 

 the tissue separating the two pollen sacs of each lobe is broken 

 down and the two cavities merge into one. Such anthers are 



