THE STAMENS. 291 



protruding, they are said to be exserted ; when shorter or concealed 

 within, they are included ; terms which apply to other organs as 

 well. So of terms which indicate their direction ; as declined, when 

 curved towards one side of the blossom, as in the Horsechestnut. 



521. The stamens are mostly too narrow to furnish any charac- 

 ters of aestivation, except as to the manner in which each one is 

 separately disposed. In this respect they exhibit several varieties, 

 to which the same terms are applied as to the vernation of indi- 

 vidual leaves (257). 



522. When the stamen is destitute of the filament, or stalk (Fig. 

 369, a), the anther (b) is said to be sessile : the 



filament being no more essential to the stamen l 

 than the claw is to the petal, or the petiole to 

 the leaf. When the anther is imperfect, abor- ( 

 tive, or wanting, the stamen is said to be sterile, 

 abortive, or rudimentary ; its real nature being 

 known by its situation. 



523. The Filament, although usually slender 

 and cylindrical, or slightly flattened, assumes a 



great variety of forms : it is sometimes dilated so as to be undis- 

 tinguishable from the petals, except by its bearing an anther ; as 

 in the transition states between the true petals and stamens of 

 Nymphsea (White Water-Lily, Fig. 266, 267). The filament is 

 anatomically composed of a central bundle of spiral vessels or 

 ducts, which represents the fibro-vascular system of the leaf, in 

 the same state as in the petiole, enveloped by parenchyma ; the 

 outer stratum of which forms a delicate epidermis. 



524. The Anther (Fig. 369, b), which is the essential part of the 

 stamen, is usually borne on the apex of the filament ; and com- 

 monly consists of two lobes, or cells (theccc), placed side by side, 

 and connected by a prolongation of the filament called the connec- 

 tivum, or connective. As the filament answers to the petiole, so 

 the connectivum answers to the midrib of the leaf, and the lobes, 

 or cells, to the blade of the leaf; the portion each side of the mid- 

 rib forming an anther-lobe. The pollen, or powdery substance 

 contained in the anther, originates from a peculiar transformation 

 of the cellular tissue, or parenchyma of the leaf. 



525. The attachment of the anther to the filament presents three 

 principal modes. 1st. When the base of the connective exactly 

 corresponds with the apex of the filament and with the axis of the 



