132 Elementary Botany 



centre of the mouth. If a bee visits one of the flowers which 

 has its pollen matured, in order to seek for honey, it will, on enter- 

 ing the flower and plunging its proboscis into the tube, strike 

 its head against the lower anther lobes, bringing the fertile 

 lobes down against its sides, covering its body with pollen (c). 

 If it now visits another flower in the same condition, it will 

 simply have its stock of pollen increased ; but if it visits a 

 flower which has its pistil bent over, evidently the stigmas will 

 strike against the insect's back, and some of the pollen scattered 

 there will adhere to the glutinous stigmatic surface. 



Other protandrous flowers are met with in the Mallows, the 

 Geraniums, many Campanulas, the Pinks and other members of 

 the Caryophyllaceffi, many Compositse, Umbelliferse, and others. 

 Protogynous flowers are much less common, but they are 

 met with amongst the Plantains, the Scrophularias, the Mag- 

 nolias, and other species of plants. 



Another arrangement is known under the name of hetero- 

 stylism, where the pistils and stamens of different flowers are 

 of various lengths. A good example of a heterostylic flower 

 is to be found in the common Primrose. If we examine a 

 bunch of common Primroses we shall find the flowers of two 

 different kinds. Some have a little knob filling up the mouth 

 of the corolla tube, and others a rosette. On making a vertical 



section of one of each kind of 

 flower, we 'find the arrangement 

 as shown in fig. 253. In the 

 first case we have the pistil with 

 a long style (253, i.), the stigma 

 of which forms the ' knob ' filling 

 up the corolla tube, whilst the 

 stamens are placed low down in 

 Fig. 2S3.-Diinorphic flower oiPri. the tube. In the Other case the 



mula. I. Long-styled, II. Short- 

 styled form : a, corolla ; b, anthers ; stamcns are high up, forming the 



c, ring of hairs ; d, pistil. , , , , / v , ., , 



'rosette (253, 11.), whilst the 

 style is short and the stigma at about the same height as the 

 stamens in the preceding variety. Such a flower is said to be 

 dimorphic, and we can speak of the ' long-styled ' and ' short- 

 styled ' varieties of Primrose. There is a slight difference in the 



