460 PART IV. CLASSIFICATION. 



and structure, or from their relation to allied hermaphrodite forms, 

 that they are typically monoclinous, but have become unisex- 

 ual by suppression : thus, in the Cucurbitacese some genera (e g. 

 Cucurbita, Cucumis, Bryonia, etc.) have unisexual flowers, whilst 

 in others the flowers are always hermaphrodite ; similarly, in the 

 Caryophyllacese, the flowers are generally hermaphrodite, but in 

 the species Lychnis vespcrtina and L. diurna they are unisexual. 

 In some unisexual flowers traces of the missing organs are to be 

 found, such as staminodes in carpellary flowers (e.g. Feuillea 

 among the Cucurbitacese ; Laurus nobilis), or rudimentary pistils 

 in staminate flowers (e.g. Rhamnus cathartica, Lychnis vespcrtina 

 and diurna). 



It sometimes happens that typically dioecious plants become 

 exceptionally monoecious (e.g. development of ? flowers on ^ 

 plants of Cannabis sativa ; or of ^ flowers on ? plants of 

 Cannabis sativa and Mercurialis annua) : or that a typically 

 monoecious diclinous plant bears some monoclinous flowers (e.g. 

 Ricinus). 



The Andrcecium comprises the microsporophylls (one or more) 

 of the flower, the stamens. Each stamen usually consists of two 

 parts ; a slender stalk called the filament (Fig. 276 s), and a 

 placental portion which bears the pollen-sacs (Fig. 276 D p,) known 

 as the anther (Fig. 276 a). The anther consists of two longi- 

 tudinal halves, termed thecce, each of which usually contains two 

 pollen-sacs ; these two halves are united by the placental portion 

 of the filament which is known as the connective (Fig. 276 c). 

 This is occasionally very narrow, so that the two halves of the 

 anther lie close together (Fig. 276 A l a): in this case it may be 

 that the anther is not sharply marked off from the filament, and 

 is attached throughout its whole length to the filament (aclnatc, 

 Fig. 277 C) : when the anther is sharply marked off from the 

 filament, it may be attached to the filament by its base, when it is 

 said to be innate or basifixcd (e.g. Tulip) ; or the filament is in- 

 serted in the middle of its dorsal surface, when it is dors (fixed 

 (Fig. 277 A) ; in the last case it may be articulated as by a joint, 

 so that the anther with the connective can oscillate on the apex 

 of the filament (versatile anther, Fig. 276 C), as in Grasses aucl 

 some other plants. But the connective is often broader, so that 

 the two halves of the anther are widely separated (Fig. 276 B) : 

 it may be much elongated (distractile) and very delicate, so that 

 with the filament it forms a T-shaped body (Fig. 276 C) ; in this 



