RHCEADINJE. 



397 



others a two-locular (half) anther. Cori/dalis and Fumaria stand alone in the 

 symmetry of the flower, differing from Dicentnt in having only one of the lateral 

 petals (Fig. 893 B, sp) prolonged into a spur, while in Dicentra both the 

 petals are spurred. This structure has been interpreted in various ways. 

 According to Asa Gray the median stamens are absent in the last-named 

 genera, and the lateral cues are split in a similar manner to the petals of 

 Hypecomn. Another, and no doubt the most reasonable theory (adduced by 

 De Candolle), is : that two median stamens are split, the two parts move 

 laterally, each to their respective sides and become united with the two lateral 

 stamens ; this affords a natural explanation of the two half-anthers, and estab- 

 lishes a close relationship to the Cruciferas. A third interpretation, held by 

 Eichler and others, is as follows : the median stamens are always wanting ; 

 when they appear to be present, as in Hypecouni, it is due to the fact that the 



FIG. 393. .Fumaria officin- 

 alis : A the flower in longi- 

 tudinal section ; B the anrlroe- 

 cium nnd gvnoeceuin ; nectary 

 to the right. 



FIG. 396. Conjdalis cava: a a flower (Literal viaxv); 

 b the anthers lying round the stigma ; o the anthers 

 shortly before the opening of the flower; A the head 

 of the stigma; p relative position of the parts of the 

 flower during the visit of an insect. 



side portions of the lateral stameus approach each other (as interpetiolar 

 stipules) and coalesce into an apparently single stamen. 



130 species ; mostly from the northern temperatures. 



POLLINATION. Fumaria, with its inconspicuous flowers, has to a great 

 extent to resort to self-pollination. Cori/dalis, on the other hand, is dependent 

 oil cross-pollination ; C. cava is even absolutely sterile with its own pollen. 

 Corydalis is pollinated by insects with long probosces (humble-bees, bees), 

 which are able to reach the honey secreted in the spur ; as they alight on the 

 flowers they press the exterior petals on one side (Fig. 396 e}, so that the 

 stigma, surrounded by the anthers, projects forward ; the proboscis is intro- 

 duced in the direction of the arrow in the figure, and during this act the 

 under-surface of the insect is covered with pollen, which is transferred by similar 



