MOEPHOLOGY OF EEPEODrCTIVE ORGANS 171 



of the filament to the other, but in some cases the original direc- 

 tion is departed from in a remarkable manner, and the upper 

 part of the filament forms an angle more or less obtuse with 

 the lower, in which case it is termed geniculate, as in Mahernia. 

 A similar appearance sometimes arises from the presence of 

 an articulation at the point where the angle is produced, as 

 in Ewphorbia (fig. 338, a). In such a case, or whenever an 

 articulation exists on the apparent filament, this is not to be 

 considered as a true filament, but as consisting in reality of a 

 flower-stalk supporting a single stamen. The flower here, 

 therefore, is reduced to a single stamen, all the parts except 

 the latter being abortive. This is proved by the occasional 

 production in some allied plants of one or more whorls of 

 floral envelopes at the point where the joint is situated. 

 In the Pellitory [Parictaria), the filament assumes a spiral 

 direction. 



Duration. — The filament usually falls off from the thalamus 

 soon after the flower opens, or is deciduous ; but in rare cases, 

 as in the species of Campanula, the filament is persistent, and 

 remains attached to the ovary in a withered condition. 



2. The Anther ^The anther is essentially a cluster or 



sorus of microsporangia, the latter being coherent together. 

 The number of the sporangia varies in different families ; there 

 are many in some of the Cycads, two in the genus Pinus, and 

 usually four in the Angiosperms. The sorus is not covered 

 by any indusium as in the Ferns, though this structtu'e is repre- 

 sented in the young anthers of the Cupressinese by a slight out- 

 growth irom the surface of the sporophyU. The sporangia 

 being coherent together, the anther has usually a somewhat 

 swollen appearance. Their disposition enables us to observe 

 in a transverse section two parallel lohes, B, e, separated by a 

 portion, A, a, called the connective, to which the filament is 

 attached. Each lobe shows the cavities of two microsporangia, 

 d, d, d, d, separated by a septum which passes from the con- 

 nective to the walls of the anther. The microsporangia contain 

 the pollen-grains or microspores. The anthers of Angiosperms 

 in an early stage of development possess four microsporangia, 

 and this is considered the normal state. When a fully developed 

 anther exhibits a similar structure, as in the Flowering Eush,it 

 is four-celled or guadrilocular {figs. 340, b, and 861, I) ; when, 

 as is far more commonly the case, the partitions separating the 

 two sporangia of each anther-lobe become absorbed, it is tivo- 

 celled or bilocular {fig. 360). In rare cases the anther is 



