322 



THE LOWER DICOTYLEDONS. 



STIGMA 



more or less perigynous. The honey, secreted by a narrow 

 ring, or by 5 or 10 glands, at the bases of the stamens, 

 is accessible to short-tongued insects, though those with 

 rather large flowers (e.g. Greater Stitchwort) are also visited 

 by bees. 



Knawel (Scleranthus), Pearlwort, and Chickweed are homo- 

 gamous and largely self-pollinated, Chickweed having in 

 winter cleistogamic flowers. These, as well as the Sandworts 

 and Spurreys, are visited by flies. Sagina nodosa (Pearlwort), 

 Cerastium (Mouse-ear Chickweed), Lesser Stitchwort, and the 

 Spurreys (Spergula and Spergularia) are more or less pro- 

 tandrous but capable of final self-pollination, while Greater 

 Stitchwort is almost completely protandrous with but little 

 self-pollination. Arenaria trinervia is exceptional in being 

 protogynous, while Arenaria peploides (Sea Purslane) is poly- 

 gamous. 



In the Sileneae the flower is made tubular by the gamo- 

 sepalous calyx, the petal-claws and stamens partly filling the 



tube and making the 

 honey (secreted by a 

 nectary on the receptacle 

 at the base of corolla, 

 Fig. 125) inaccessible to 

 any but long-tongued 

 insects (bees, butterflies, 

 moths), small insects 

 being further excluded 

 by the "corona" of 

 scales on the petals in 

 Silene and Lychnis (exc. 

 L. githago). The Silene- 

 ae are generally very pro- 

 tandrous ; the Red and 

 the White (Evening) 

 Campions are dioecious, 

 while Bladder Campion 

 is polygamous. 



In most cases butterflies are probably the chief visitors, 

 but Evening Campion and several kinds of Catchfly are 

 moth-pollinated, the flowers opening and becoming heavily 

 scented only at night and having conspicuous white or pale 



NECTARY 



Pig. 125. Longitudinal Section of Flower of 

 Clove Pink. 



