158 FLOWERS OF THE ROADSIDES AND HEDGES 



The plant is often 15 ft. high, and grows in clumps, several being 

 associated together forming bush-land. It is one of the earliest wild 

 flowers in March and April. The Sloe is a deciduous shrub, propa- 

 gated by seeds. 



The flowers are conspicuous, and contain abundant honey, and 

 owing to their appearance before the leaves and the early flowering are 

 much visited by insects. The stigma matures before the anthers. 

 In the first stage the style is considerably above the stamens. The 



BLACKTHORN (Pntnus spinosa, L.) 



anthers have not yet opened, and are bent down towards the centre 

 The stigma is already receptive, and projects. It is therefore first 

 touched by an insect visitor, the petals becoming more or less hori- 

 zontal. The stamens become erect, and bend outwards. The outer 

 anthers open first. The style lengthens and overtops the short 

 stamens, which stand near the centre. As the stigma is at this stage 

 still receptive, self-pollination may thus occur by the agency of insect 

 visitors. In their absence self-pollination may occur as the flowers 

 turn to the sun, from the inflection of the stamens toward the centre 

 above the stigma, causing pollen to fall on the latter. 



The flower is visited by Hymenoptera (Apidse), Diptera (Empidae. 



