II 



86 A TEXTBOOK OF THEORETICAL BOTANY 



Diapensiaceae. More frequently, though ahnost Hmited to the large 

 families of Berberidaceae and Lauraceae, the lines of dehiscence are U- 

 shaped, and mark out either two or four flaps, or valves, which fold back, 

 exposing large openings (Fig. 1 158). 



The attachment of the anther to the filament is by means of the con- 

 nective. 'J'his is generally a narrow shaft of tissue, through which runs a 

 single vascular bundle from the filament. When the connective itself forms 

 a direct prolongation of the filament the anther is called basifixed. If, on 

 the contrary, the filament is attached to the abaxial side of the connective 

 it is called dorsifixed. Filaments attached to the upper end of the con- 



Fio. T 159. — Liliuni mortagott showing versatile 

 anthers. 



nective (apicifixed) are rare and are usually associated with widely diver- 

 gent anther lobes {e.g., Lamiwn). When the attachment to the filament is 

 limited to a single point of the connective, the anther may be free to oscillate 

 on this point, as in Passiflora, Liliiim (Fig. 1159), and the Gramineae 

 generally. It is then known as versatile, and in the grasses this freedom of 

 movement is certainly useful in promoting wind-pollination. 



The behaviour of the stamens at anthesis is very variable, according to 

 the mode of pollination in particular species, and details are given of a 

 number of examples in Chapter XXIV. 



A not infrequent occurrence is the successive development and growth, 

 either of individual stamens or of complete whorls, the later-formed re- 

 placing in turn the earlier stamens, whose pollen has already been shed. 

 1 his is often accompanied by growth curvatures whereby the anthers as 



