290 



THE STRUCTURE OF FLOWERS. 



and blades of the leaves is seen in Bipterocarpus and Mus- 

 scBnda (Fig. 68). Transitional states from a single to a 

 double flower of Saxifraga decipiens, described and figured 

 by M. C. Morren,* shows that the newly foi-med petals in 

 the place of stamens, as also the normal petals of the flower, 

 exactly correspond, both in shape and venation, with tbe 

 cotyledons. Palmate venation thus simply represents a more 

 primitive type ; and, since flowers are constructed out of 

 metamorphosed leaves — ^the vegetative being replaced by 

 reproductive energies, — one naturally expects to find the 

 calyx and corolla, which more nearly approach leaves in 

 structure, to show arrested foliar con- 

 ditions, as, e.g., are seen in palmate 

 nervation and absence of blade or 

 petiole, as the case may be. 



In Musscenda (Fig. 68) the teeth 

 of the sepals are usually subulate and 

 acuminate ; but in the one foliaceous 

 and snbpetaloid sepal it is drawn out 

 into a long petiolar form, which then 

 expands into a palmately nerved 

 lamina. The fact that a "tooth" is 

 in this case prolonged into a " petiole " 

 seems to imply that the sepal arises 

 at once from the receptacnlar tube, 

 which, therefore, one would infer to 

 be axial. A somewhat analogous pro- 

 cedure is in the monstrous Trifolium, 

 where the unifoliate blades, supported on long pedicels with 

 stipular appendages as well, all arise from the border of tbe 

 so-called calyx-tube (Fig. 67). There the inference would 

 be the same, only that the receptacnlar tube is free from the 



• Les Bull, de I'Acad. Ray. de Bruxelles, t. xvii., p. i., p. 415. 



Fig. 68.— Flower and leaf of 



