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 
Photo. Rev. C. A. Hall 
BLACKTHORN (Prunus 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 (Apidz), Diptera (Empide, 
