222 



FLOWERS AND THEIR WORK. 



..CONNECTIVE 



--POLLEN 



Fig. 72. An Anther with the top 

 cut off. 



254. The Andrecium is the collective term applied to the whole 

 of the stamens present in any single flower. Each stamen usually con- 

 sists of two parts, a stalk or fila- 

 ment, and a head or anther. There 

 may be no filament, so that the 

 anther is sessile, or the anther may 

 not develop, when what remains is 

 known as a staminode or sterile stamen. 

 The anther is usually divided into 

 two halves or lobes, in each of which 

 are two longitudinal compartments, 

 filled, when ripe, with pollen grains. 

 When the anther splits open, or 

 dehisces, the partition between the 

 paired pollen sacs of each lobe breaks 

 down to a greater or less extent, so 

 that each lobe appears to have only 

 a single cavity (Fig. 72). 



The prolongation of the filament 

 between the two lobes of the anther 

 is termed the connective. When the 

 lobes are close together, this is nar- 

 row ; but in Labiates and some other 

 The right anther lobe is represented plants the connective is elongated 

 as being dehisced. laterally, and the anther lobes are 



widely separated. Special append- 

 ages are occasionally developed from the connective ; each anther of 

 the Violet has a membranous orange -coloured outgrowth at its apex, 

 and in addition each of the two anterior stamens has an elongated 

 process extending downwards into the spur of the anterior petal. 

 The tip of this process is glandular, and secretes nectar into the 

 spur. 



As a general rule the different stamens of a flower are alike in 

 shape, size, and in length of filament. Two of the stamens of the 

 Wallflower, however, are shorter than the other four (tetrady- 

 namous), while the Dead-nettle has two long and two short stamens 

 (didynamous). 



The fully grown anther breaks open and allows the pollen 

 to escape. It usually happens that the wall of each lobe splits 

 longitudinally along the dividing line between its two compart- 

 ments, but in many Labiates the anther opens transversely. In 

 Potato, Rhododendron, Milkwort, etc., small pores are formed at 

 the top of the anther. In the Barberry the whole side of each 

 anther-lobe bends upwards ; in the Laurel small doors or valves 

 open at the sides of the anther. 



Examine and sketch the stamens of the following flowers : 

 Buttercup, Gorse, Sweet Pea, Mallow, Potato, Violet, Pansy, 

 Wallflower, Rhododendron, Heather, Dead-nettle, Foxglove, Bar- 

 berry, Bay Laurel, Fumitory, Dicentra ("Bleeding Heart"), Garden 



