8o PROCEEDINGS OE TITE 



of attractina; visitors required for cross-fertilization, if its slender 

 stems lost themselves amongst surrounding vegetation, instead of 

 forming dense tufts covered with bright flowers. These tuFts also 

 send out much larger volumes of tl>e odour so characteristic of the 

 plant than isolated stems would do, and thus afford an additional 

 attraction to insects. 



In the pretty little moscatel (Ado.va Moschatellhia) we have a 

 rare instance of an entomophilous plant emitting a slight odour, 

 secreting nectar, and yet being devoid of the brightly coh)ured 

 corolla which we associate with such distinctly entomophilous 

 plants. Grrant Allen tells us that no reason Ciin be given for the 

 green corolla of this plant, but I would suggest that the formation 

 of colonies of these bright green plants bjf undert/round stems 

 renders them very conspicuous in contrast with the brown colora- 

 tion of our woodlands in spring, and thus bright-coloured corollas 

 are not necessary. 



I would now direct attention to the two most characteristic 

 cleistogamic flower-producing plants of our British flora. Careful 

 observation will show us that these cleistogamous flowers not only 

 serve the plants by producing mature seeds without the aid of 

 wind or insects — an important service, but also by keeping the 

 colonies of plants dense in their very centres, and by this means 

 enabling the colonies to maintain themselves against outside attack 

 for much longer periods. 



The sweet violet (Viola odorata), growing in woods and hedges 

 surrounded by luxurious vegetation, would soon be smothen^d if 

 growing as isolated plants or in straggling colonies. Tlie plant 

 thrusts the capsules, produced by the cleistogamous flowers 

 abundantly in the autumn, to the ground close to the parent 

 plant; thus a number of vigorous young seedlings are introduced 

 into the colonies, reinvigorating them at their centres, whilst the 

 creeping stems spread outwards and extend the colonies in a 

 centrifugal manner. The seeds produced by the jierfect flowers, 

 which serve to start new colonies, are very sparingly produced, 

 hence it is important to the plant that the colonies, when once 

 established, should hold their own for a lengthened period. 



It is noteworthy that the dog violet (Viola canina), growing in 

 more open situations and surrounded by less luxuriant vegetation, 

 relies much more u])on its perfect flowers for the reproduction of 

 the species. These perfect flowers are produced later in the 

 season, when insects are more abundant, and consequently pro- 

 duce an abundance of seed. They thrust the capsules produced 

 by these perfect flowers well above the surrounding vegetation 

 and scatter their seeds very widely. The plant appears to realize 

 that it lives under different conditions to those under which its 

 near relative the sweet violet has to struggle, and takes full 

 advaTitnge of the more favourable conditions. Nevertheless it 

 develops cleistogamic flowers, and plants the seeds produced by 

 them inside the colonies, though relying less upon them. It is 



