THE DICOTYLEDONES 



1925 



at the base into a very short tube. The posterior sepal is missing and the 

 two posterior petals are fused into one large member. There are only two 

 stamens which, with the style, project considerably beyond the flower. 

 The flowers (Fig. 1852) are mostly pollinated by hover flies which 

 alight on the stamens. A fly visiting a flower finds the lowermost 

 corolla lobe the most convenient place to settle and in doing so 



Fig. 1852. — Vsronica. Flowers to illustrate pollination. See in 



in text. 



comes into contact with the stigma, which is projecting slightly 

 downwards. At the same time the visitor seizes the filaments of 

 the stamens, drawing them together and thereby dusting the lower 

 surface of its body with pollen. In this way it follows that, akhough 

 style and stamens mature at the same time, the style is pollinated by pollen 

 from the body of the fly before it becomes dusted with the pollen of 

 that flower. According to Kerner in those species in which the flowers 

 develop in spikes geitonogamy may also take place. 



LAMIALES 



The Lamiales may be defined as Metachlamydeae in which the leaves 

 are mostly opposite or in whorls, the corolla is zygomorphic and funda- 

 mentally pentamerous, the stamens fewer than the corolla lobes, the ovary 

 deeply lobed with a gynobasic style, and ovules are mostly paired. 



This order as treated by Hutchinson includes five families, one of which, 

 the Selaginaceae, we have already dealt with as a tribe of the Scrophu- 

 lariaceae. Two only need be considered here, the Verbenaceae and the 

 Labiatae. 



The Verbenaceae are a small family of eighty genera and about 800 

 species, which are almost entirely tropical or subtropical in distribution. 

 Only Verbena officinalis occurs in Britain. It is a small herbaceous plant 

 with long flower spikes bearing rather inconspicuous violet flowers and is 

 interesting for having been the object of superstitious veneration from the 



