360 



STAMENS 



A single vascular bundle traverses filament and connective. 

 In the vast majority of cases the anther bears four pollen sacs, 

 two on either side of the connective (Fig. 209, A), although 

 the stamens of the Mallow-family (Malvaceae), for instance, have 

 but two pollen sacs. In transverse sections through very young 

 immature flower-buds, the anthers are seen to consist of uniform 



D. 



FIG. 209. Development of the anther. A, Section of rather more than 

 half the anther of a young stamen, showing the pollen-sacs at the 

 mother-cell stage (the mother-cells are seen in various phases of 

 division). B, Section of young anther before the archesporia are 

 differentiated. C and D, Later stages, a., dividing archesporial cells ; 

 ep., epidermis of anther ; /., fibrous layer ; fil., filament ; m.l., middle 

 layer ; t., tapetum ; v.b., vascular bundle of connective. (A original, 

 the remainder after Warming.) 



thin-walled tissue bounded by a distinct epidermis, whilst a 

 slight lobing foreshadows the future pollen sacs (Fig. 209, B). At 

 a slightly later stage four subepidermal strips of varying \\idth 

 (often of only a single cell) become distinguishable, one in each 

 lobe ; these strips consist of cells with prominent nuclei and 

 dense contents and constitute the archesporia (Fig. 209, C, a.), each 

 of which extends as a narrow band of tissue for almc-st the whole 



