THE DICOTYLEDONES 



1637 



Corydalis are myrmecochorous, the seeds being attractive to ants. Some of 

 the species of both genera are pecuHar in having only a single cotyledon, a 

 condition which, it has been suggested, may be associated with the develop- 

 ment of a fleshy tuber or rhizome. 



The pollination mechanism is quite distinct from that in either of the 

 other sub-families. The flowers are zygomorphic and are pollinated by bees. 

 The nectar is secreted in spurs or pouches formed from the petals; there 

 being two nectaries in Dicentra but only one in Corydalis and Fiimaria. 

 The two inner petals are fused at the top to form a hood-like sheath which 

 encloses the stamens and stigmas. The bee presses down the hood when 

 seeking nectar, but it springs back to its original position when the pressure 

 is removed. In the younger flowers the bees become dusted with pollen 

 and later transfer it to older flowers. The bee in visiting each flower of an 

 inflorescence from below upwards will, therefore, effect pollination mainly 

 from one inflorescence to another. 



Fig. 1498. — Dicentia spectabilis. 

 Longitudinal section of flower. 



In Dicentra spectabilis (Fig. 1498) the petals and stamens form grooves, 

 at the base of which lies the nectar. So elaborate is this system of grooves 

 that only two native bees are able to reach the nectar and they alone nor- 

 mally perform pollination. 



In Corydalis (Fig. 1499) one of the two outer petals is prolonged back- 

 wards into a spur containing nectar. The two inner, lateral petals are fused 

 at their tips and cohere at their bases with the two outer petals, thus forming 

 a hood which encloses the anthers and stigma. Long-tongued bees in 

 search of the nectar must insert their probosces between the hood and the 

 upper spurred petal and in doing so they press down the hood, with the 



