112 Flowers and their Unbidden Guests. 



nium, e.g.. Geranium Rdberiianwn. Here there is a 

 single ridge on each petal. These ridges jut out to- 

 wards the centrally-placed ovary with its surround- 

 ing stamens, and are closely pressed against it Hke 

 so many huttresses. This results, as shown in the 

 transverse section of a flower of this species (Plate II. 

 fig. 62), in the formation of five narrow passages 

 leading directly to the nectar, which is secreted by the 

 base of the filaments at the bottom of the flower. 



In many cases the self-same saccular pouch of the 

 perianth that secretes or stores the nectar is also so 

 developed as to constitute the narrow passage. The so- 

 called spurs which are found in the most widelyseparated 

 families, sometimes on the calyx, as in Tropseolum, 

 sometimes on the perianth, as in Platanthera, some- 

 times on the corolla, as in Epimedium macrantlmrn,, 

 are for the most part of this character. Gymnadmia 

 odoratissiTna, of which a representation is given at 

 Plate II. fig. 54 (longitudinal section of flower), may be 

 quoted as an example. Frequently again these nectari- 

 ferous pouches are twisted in a spiral manner. This 

 makes them still more inaccessible to the smaller insects, 

 while it does not interfere in the very least degree with 

 such as have a proboscis that can be coiled up. Such, 

 for instance, is the case in Aquilegia and Aconitum (Plate 

 II. fig. 44, petal of Aconitum faniculatuTn), where the 

 limb of the petal is deeply saccate, and the resulting 

 pouch rolled back in a spire. Another and analogous 



