1728 



A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 1603. — Stellaria holostea. Stitchwort. 

 Flower. 



Fig. 1604. — Stellaria i^raiiiinea. Polli- 

 nation. A, P'lower in male stage. 

 B, Flower in female stage with 

 expanded stigmas. {After Kutitli.) 



In many genera the petals are 

 bifid and there is great variation in 

 the number of the styles and the 

 number of valves in the capsule. 



The pollination mechanism is 

 interesting. All the flowers secrete 

 nectar and most are visited by flies 

 and the less specialized bees, in con- 

 trast to the members of the Sileno- 

 ideae in which long-tongued insects, 

 such as butterflies and moths, are 

 the chief visitors. This is because 

 the long tubular calyx of the latter 

 renders the nectar inaccessible to 

 short-tongued insects. 



Many of the flowers are dichoga- 

 mous, in which case they are nearly 

 always protandrous. Automatic self- 

 pollination is probably possible in all 

 species. Though the details differ 

 appreciably in the different genera 

 we may cite the condition in Stellaria 

 graminea (Fig. 1604) ^^ an example. 

 In this flower five nectaries are 

 arranged in the form of a green, 

 fleshy ridge, at the base of each of 

 the five outer stamens. The flowers 

 are protandrous and when they open 



