356 HUTCHINSON'S POPULAR BOTANY 



runs transversely to the filament, to which it is attached by a movable 

 joint, the purpose of which will be explained hereafter. From some stamens 

 the filament is entirely absent, and the anthers, which are then described as 

 sessile, may be attached either to the petal of the flower, as in Vervain 

 (Verbena), or to some part of the pistil, as in the Birthwort (Aristolochia). 

 In a large number of cases the connective is perfectly continuous with 

 or, in other words, is a direct prolongation of the filament, the point of 

 attachment of the anthers being immediately upon the top of the filament ; 

 but far more frequently the latter is prolonged up behind the anther-lobes. 

 The terms basifixed or innate and dorsifixed or adnate are applied respectively 

 to these two kinds of attachment. 



When the face of the anther or, in other words, the surface opposed to 

 that to which the connective is attached is turned towards the pistil of the 

 flower, the stamens are said to be introrse ; when, on the other hand, the 

 face is turned towards the petals, the stamens are extrorse. The direction in 

 which the anthers dehisce that is, discharge their pollen is thus largely 

 dependent upon the position of the stamens a fact to be carefully noted. 



The mode of de- 

 hiscence is chiefly 

 determined by the 

 nature of the aper- 

 tures through which 

 the pollen escapes. 

 When, as is most 

 frequently the case, 



FIG. 437.-STAMENS OF (a) LITS^A ; (6) PYBOLA ; (c) GAKCINJA. the anther Opens by 



narrow upright slits 



running from top to bottom of the lobes, the dehiscence is said to be 

 longitudinal ; when the lobes are slit crosswise, the dehiscence is transverse. 

 In not a few flowers the lobal orifices are wide and concealed by delicate 

 valves or flaps, which lift up like a trap-door at the moment of shedding 

 the pollen. This is valvidar dehiscence. When, as in the case of the 

 Common Whortleberry (Vaccinium myrtillus), the dehiscence is effected 

 by minute fissures or pores at the tips of the lobes, we speak of it as 

 porous. 



The anthers assume the most various shapes globular and oval, 

 pear-shaped and worm-shaped, curved and undulating (the latter a form 

 which reminds one of the convolutions of the human brain), pitcher-like 

 and box-shaped, etc., etc. ; while many of these forms are rendered still 

 more striking by the presence of appendages in the shape of hairs, tubes, 

 fleshy hooks, leaf-like expansions, coloured bladders for attracting insects, 

 feathery growths, and other singular contrivances whose name is Legion. 

 Such appendages are usually prolongations of the connective. The almost 

 naked stamens of Leitneria floridana, a shrub with willow-like leaves 



