220 ESSENTIAL ORGANS. — STAMENS. 



Orchidacese. The column is called gynostemium (yuvfi, pistil, and 

 (rryifiiav, stamen), and the flowers are denominated gynandrous (yuvri, 

 pistil, avri^, male or stamen). 



In the case of certain Achlamydeous (p. 192) flowers, as Euphorbia, 

 with only one stamen developed, there is the appearance of a jointed 

 filament bearing one anther. This, however, is not a true iilament, 

 but a peduncle with a single stamen attached to it, as proved by the 

 fact, that in some species of Euphorbia one or more verticils are pro- 

 duced at the joint. In this case the apparent anther represents a 

 single flower supported on a stalk, all the parts being abortive except 

 a solitary stamen. 



The Anther corresponds to the blade of the leaf, and consists of 

 lobes or cavities containing minute powdery matter, called pollen, 

 which, when mature, is discharged by a fissure or opening of some 

 sort. The anther-lobes may be considered as formed by the two halves 

 of the lamina, their back corresponding to the under surface, and their 

 face to the upper surface, united by the midrib, the pollen being 

 cellular tissue, and the fissure of the anther taking place at the margin, 

 which, however, is often turned towards the face. In this view, the 

 two cavities which are foimd to exist in each lobe may correspond 

 with the upper and under layer of cells, separated by a septum 

 equivalent to the fibro-vascular layer of the leaf Others view the 

 anther as formed by each half of the lamina being folded upon itself, 

 so that the outer surface of both face and back corresponds to the 

 lower side of the leaf, and the septum dividing each cavity into two is 

 formed by the united upper surfaces of the folded half 



There is a double covering of the anther — the outer, or exothe- 

 cium (s^M, outwards, Si^xiov, a covering), resembles the epidermis, and 

 often presents stomata and projections of different kinds (fig. 350 ce) ; 

 the inner, or endothecium (svBov, within), is 

 formed by a layer or layers of flbro-cellular 

 tissue (fig. 350 c/), the cells of which have 

 a spiral (fig. 23), annular (fig. 24), or reti- 

 culated (fig. 25) fibre in their interior. 

 This" internal lining varies in thickness. 

 Fig. 360. generally becoming thinner towards the part 



where the anther opens, and there disappears entirely. The membrane 

 of the cells is frequently absorbed, so that when the anther attains 

 maturity the fibres are alone left, and these by their elasticity assist 

 in discharging the pollen. The cells in the endothecium of Armeria 

 maritin?^ and Pinguicula vulgaris are reticulated, while annular cells 

 occur in the endothecium of Cardamine pratensis. 



Fig. 350. Transverse section of a portion of the covering of the anther of Cobeea scandens 

 at the period of dehiscence, ce, Exothecium, or external layer, consisting of epidermal 

 cells, c/, Endothecinra, or inner layer, composed of spiral cells or Inenchyma. 



