PETIOLES 



39 



In another species of Delphinium (D. nudicaule) (fig. 82) 

 the cotyledons are raised well above the surface of the ground 

 on a stem consisting of their own two stalks or petioles, which 

 are connate, though readily separable from one another. 

 Connate cotyledons also occur in Phlomis tuberosa, Smyrnium 

 perfoliatum (fig. 77), Polygonum Bistorta, 1 &c. Gray 2 ob- 

 serves that the economy of this arrangement is not apparent. 

 Assuming, however, that the elevation of the cotyledons is 

 an advantage, perhaps, as I have suggested, from carrying 



FIG. 77. Seedling of Smyrnium 

 perfoliatum. Half nat. size 



FIG. 78. Germinating seedling of 

 Geranium bohemicum, x 6. 



them above the surrounding herbage, the combination of the 

 two petioles reversing the old fable of the bundle of sticks 

 would, with the same amount of material, give a considerable 

 addition of strength. 



For instance, in Smyrnium perfoliatum (fig. 77) the 

 hypocotyl is undeveloped, the cotyledons are oblong-elliptic, 

 emarginate, obtuse, generally unequal-sided or subfalcate, 

 with long petioles, 3-nerved from the base, and finely reticulate, 



1 Winkler, 'Ueber die Keimbliitter der deutschen Dicotylen,' Bot. Verh. 

 Brandenburg, 1874. 2 Structural Botany, p. 21. 



