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A TEXTBOOK OF THEORETICAL BOTANY 



swells out and is covered by hairs. It narrows again and at its apex bears 

 an anther w4th tw^o inwardly directed anther lobes with long tail-like 

 appendages, which extend outwards to the corolla. Only the most skilful 



I 



Fig. 1773. — Arctostophylos uva-itrsi. A, Longitudinal 

 section of flower in bud stage. B, Stamen with apical 

 dehiscence pores and filamentous appendages. (After 

 Kiuith.) 



Humble Bee and Hive Bee are able to get at the nectar by probing with their 

 probosces through the tubular opening in the pendulous flowers. If the 

 insect's head is covered with pollen it is almost certain to touch the stigma, 

 which lies centrally just below the opening of the corolla. As the proboscis 

 is thrust further down it meets the appendages of the anthers causing pollen 

 to be shaken on to the insect's head. Thus cross-pollination is almost 

 certainly ensured. Since the flowers are pendulous, pollen at the end of 

 anthesis may become loose and fall on the stigma, so that as a last resort 

 self-pollination may occur. 



As already mentioned, the members of the Vaccinioideae are sometimes 

 separated as a distinct family. The genera are mostly temperate in distribu- 

 tion or occur on the tops of tropical mountains, and are usually modified as 

 xerophytes or epiphytes. The 350 species are distributed among about 

 twenty-five genera, of which Vaccinium, with 100 species, is the best 

 known. 



The flowers are feebly protandrous, with concealed nectar, and are 

 pollinated by bees. In V. myrtillus (Fig. 1774) the flowers are bright green 

 in colour with a reddish tint, and are quite devoid of scent, but despite this 

 they are very rich in nectar. The pendulous corolla is contracted at its tip 



