160 BETONICA, CALAMINTHA, THYME. [CHAP. 



palustris the tube is shorter than in 5. sylvatica ; the 

 four stamens are of equal length ; and when the flower 

 opens, the anthers of the outer ones lie in front of 

 the inner ones. When they have shed their pollen 

 they turn outwards, thus exposing the inner ones, 

 which in their turn shed their pollen, and then 

 move outwards to make room for the pistil, which 

 thus occupies the place which they had previously 

 rilled. 



Betonica officinalis is also proterandrous ; the pistil 

 being comparatively short when the flower first opens, 

 and not attaining its full length until the anthers 

 have shed their pollen. 



In Calamintha Clinopodium the upper process of the 

 stigma varies considerably in size. The stamens are 

 still more remarkable in this respect, presenting vari- 

 ations which, as mentioned in the case of Galeopsis 

 tetrahit, are very interesting. 



I have already in the introductory chapter referred 

 to the Thyme (Thymus Serpyllum, Figs. 32 and 33) 

 as a type of a proterandrous flower. It is extremely 

 rich in honey, much frequented by insects, and, 

 according to Muller, has lost the power of self- 

 fertilisation. Besides the ordinary flowers, which 

 contain both stamens and pistils, there are other 

 smaller ones, which contain a pistil only. In Italy, 

 Delpirio has observed not only these two kinds, but 

 also a third in which the pistil is quite rudimentary. 

 Ogle also in England has observed that in some 

 flowers the pistil never becomes fully developed. On 

 the contrary in Germany, Hildebrand, Ascherson, and 

 Muller, have sought in vain for these male flowers. 



