THE STAMENS. 



13 



FIG. 28. 



differentiated are they as to lose all semblance of leaves (Fig. 26c) . A 

 stamen consists of two parts: a stalk-like portion (Fig. 2$a), called 

 the filament and an end or head (b), which is the anther. The anther com- 

 monly consists of two cells miniature cases which open at the proper 

 season, each usually by a longitudinal slit, to liberate their contents 

 a very fine, golden yellow powder. 



69. This is the pollen, which is to perform a very important function, 

 the fertilization of the ovule in order that it may become a seed. 

 Although to the unaided eye it is a mere powder, under the microscope 

 it is shown, to be a mass of symmetrical bodies, usually spherical 



but sometimes elongated, cubical, triangular etc., and often 

 beautifully marked with bands, checks, spines, etc., in fantastic 

 figures of endless diversity, but always constant in the same 

 species. One form of pollen grain is shown in Fig. 42-16, 17. 



70. The Insertion of the Stamens is usually the same as that 

 of the corolla, and they are said to be hypogenmu, when they 

 are inserted beneath the ovary, as in Figs. 41-2, 6; perigynous, 

 when around the ovary on the calyx-tube, the ovary itself 

 being free, as in Fig. 29; epigynous, when on the top of the 

 ovary, or on the calyx-tube adherent to the ovary to that point. 



An example of the last type is seen in the apple blossom. The stamens 

 are called epipetalous, wlien inserted on the corolla, as in most monope- 

 talous flowers. 



71. The Union of the Stamens with each other may be by means of their 

 filaments or anthers, and when no union at all exists, they are said to be 



distinct. United by their filaments they 

 are monadelphous (from Greek words sig- 

 nifying a single brotherhood), when 

 united in one set so as to form a tube or 

 ring; diadelphous (two brotherhoods), 

 when united into two sets, and so on; 

 polyadelphous when in many sets. When 

 the stamens are united by their anthers, 

 they are said to be syngenesious (from 

 Greek GVV, together, and ysvsaiS, birth.) 

 72. The Attachment of the Anther to 

 the Filament is important. The anther 



is said to be innate when it is seated, as it were, on the end of the 

 filament; adnate, when the lobes are attached, throughout nearly or 

 quite their whole length, to the opposite sides of the filament. The 

 portion of the filament between the anther-cells is called the connective. 

 A versatile anther is one balanced at about its center across the tip of 

 the filament and upon which it turns. 



73. The Dehiscence of the Anther (L. dehisco, to gape or yawn) is the 

 opening of the cells, for the discharge of its pollen. It is usually by a 

 vertical slit in each cell extending their full length, but in some classes 

 of plants it is by a chink, a terminal pore or a lid. When they open on 

 the side towards the pistil they are introrse, and when away from it 

 extrorse. 



Fig. 28. Stamen, a, filament and, b, anther with escaping grains of pollen. (From Gray.) 

 Fig. 29. Flower of the cherry, cut through lengthwise. (From Gray.) 



FIG. 29. 



