258 



STRUCTURE AND VITAL PROCESSES OF PLANTS 



stamens are free, bat tlieir syiigenesious anthera cohere and 

 form a tube. 



(6-) Filament. — The lila- ,- . 



ments may he long as in 



Crinum, or short as in Ixora, 



or absent as in Anona. Rare- 

 ly the tilament is flattened, 



as in Lotus. In the Labiatse 



and in some Acanthacese 



there are four stamens in 



two pairs of different lengths; 



in the Crucifers we find six 



Fig-. 240. -Flower StameUS, four longer and two l^'ig-- 24 l. — Flower of a 

 ofCorapositfe: shorter; in the Bilimbi tree Crucifer: four long-er and 

 Hlaments (fj) free 



five stamens are long and 



two shorter stamens. 



anthers (e) united. 



five short. 



{d) Connective. — The connective is fixed to the filament 

 usually by its base (basifixed), but in some flowers, as in Gloriosa, 

 by the middle of its back (dorsifixed). In the latter case the 

 filament becomes very thin at its end, and the heavy anther can 

 freely swing on it. This is advantageous to the plant which is 

 visited by night-moths (see pollination). Usually, the pollen-bags 

 are attached to the broad frontal sides of the connective; in the 

 Labiata^, however, they are placed at their ends (see Salvia, 

 page 106). In some flowers, again, the connective is produced 

 beyond the anther; in the Compositie it ends in a triangular 

 flap; in tlie Anonaceie in a round cap. 



(e) Anthers. — Tlie ways in which the anther-bags open 

 (dehisce) to let the pollen escape, are also difierent in difi'erent 

 plants. Commonly they dehisce in two longitudinal rents, the 

 rent beginning at the upper end. The slits become so wide and 

 th(; pollen proceeds so richly from the two bags that tlie pollen 

 becomes one lump. In the Potato the anther-bags open by pores 

 at tlioir ui)i)er ends; in Cinnamon l)y valves. In the Orchises 

 the pollen coheres and ioi'ins a dense mass. 



Finally, it may be remarked that the anthers in some flowers 

 open towards the centre (SunHower), and in others towards the 



