160 Plants and their Ways in South Africa 



in use. When a flower is visited, the tongue is uncoiled and 



^ thrust down the flower after 



:3j> 3$&-, honey. If the bee has just 



FIG. 157-Diagram of bee's tongue after visited * fl W6r with Ion g 



visiting Oxalis with long and short and short stamens, there 

 stamens - will be tell-tale marks on 



its tongue, as shown in Fig. 157. When it visits another 

 flower with long stigmas the pollen will be brushed off on the 

 upper part of the tongue, and short stigmas of a flower will 

 brush it off below. 



In Gazania and Cryptostemma the stamens are joined by 

 their anthers, making a collar around the stigma. Watch the 





FIG. 158. Trimorphic flowers of Oxalis cernua, Thunb. The arrows 

 indicate the legitimate combinations. (From Edmonds and Marloth's" Ele- 

 mentary Botany for South Africa".) 



flowers of the disk in the centre. The outer flowers of the disk 

 open before the inner ones on successive days. On a bright 

 morning their long club-shaped stigmas push up through the 

 collar, well covered with pollen. On the following day the 

 elastic style has shortened, the five teeth made by points of the 

 stamens brush off the pollen in rings in each flower which soon 

 disappears. These stigmas open later at the top and receive 

 pollen, while closed stigmas of an inner whorl brush out rings 

 of pollen from their flowers! When they in turn are ready to 



