STKUCTUEAL BOTANY. 



row ; on its back a ridge, and on the face of each lobe a seam, 

 the usual place of dehiscence or opening, all running parallel 

 with the filament and connectile. 



114. The stamen, as thus described, may be considered regular or typical in form, and 

 is well exemplified in that of the Buttercup (fig. 83). But the variations of structure are 

 as remarkable here as in other organs, depending on such circumstances as, 1st, the at- 

 tachment of filament to antbf.r. This may occur in three ways. The anther is said to be 

 innate when it stands centrally erect on the top of the filament ; adnafe when it seema 

 attached to one side of the filament ; ve?'satile when connected to the top of the filament 

 by a single point in the back. 2d, The modes of Dehiscence or opening, are also three 

 viz., valvular, where the seam opens vertically its whole length, which is the usual way; 

 porous, where the cells open by a chink or pore, usually at the top, as in Rhododendron 

 and Potato ; opercular, when by a lid opening upward, as in Sassafras, Berberis (92). 3d, 

 The facing of the anther is also an important character. It is introrse when the lines of 

 dehiscence look toward the pistil, as in Violet ; extrorse when they look outward toward 

 the corolla, as in Iris. 4th, The connectile is usually a mere prolongation of the filament, 

 terminating, not at the base, but at the top of the anther. If it fall short, the anther will 

 be emarginate. Sometimes it outruns the anther, and tips it with a terminal appendage 

 of some sort, as in Violet, Oleander, and Paris. Again, its base may be dilated into spurs, 

 as in two of the stamens of Violet. 5th, If the connectile be laterally dilated, as we see 

 gradually done in the various species of the Labiate Order, the lobes of the anther will 

 be separated, forming two dimidiate (halved) anthers on one filament, as in Sage and Bru- 

 nella. Such are, of course, 1-celled (96). 



P 



91 



93 



95 



Peculiar forms of stamens. 89, Pyrola rotundifolia; p, dehiscence by pores at top. 90, Vaccinium 

 nliginosum; p, dehiscence. 91, Berberis aquifolium, anthers opening (92) by valves upward. 93, An- 

 ther of Violet, introrse, with aii appendage at top. 94, Oleander, sagittate, appendaged. 95, Catalpa, 

 lobes of anther separated. 96, Sage, lobes of anther widely separated, on stipes; 6, barren lobe without 

 pollen. 97, Malva, anther 1-celled. 98, Ephedra (after Peyer), anther 4-celled. 



115. The cells of the anthers are at first commonly four, all 

 parallel, becoming two only at maturity. In some plants the 

 four are retained, as in the anthers of Ephedra (98). In others, 

 as Mallows, all the cells coalesce into one (97). 



116. Appendages of many kinds distinguish the stamens of different species. In the 

 Ericaceae there are horns, spurs, tails, queues, etc. In Onions and Garlic, the filament is 

 2 or 3 forked, bearing the anther on one of the tips. Sometimes a pair of appendages 

 appear at base, as if stipulate. It is often conspicuously clothed with hairs, as in Trades- 

 cantia. (See 89-94, .) 



117. Staminodia, or sterile filaments with abortive anthers or none, occur singly in 

 many of the Figworts and Labiates, or in entire whorls nest within the petals, alternat- 

 ing with them, as in Loose-strife. The curious fringes of the Passion-flower are regarded 

 as composed of staminodia (112). 



