290 



THE STRUCTURE OF FLOWERS. 



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

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

 doable flower of Saxifraga decipiens^ described and figured 

 by M. C. Morren,* shows that the newly formed petals in 

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

 exactly correspond, both in shape and venation, with the 

 cotyledons. Palmate venation thus simply represents a more 

 primitive type; and, since flowers are constructed oufc 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 subpetaloid sepal it is drawn out 

 into a long petiolar form, which then 

 VVI /// \ \M /(/ expands into a palmately nerved 

 nW \ n r // lamina. The fact that a "tooth" is 



1 1 \\ // ^^ ^^^^ ^^^® prolonged into a " petiole " 



-■' ^ '' seems to imply that the sepal arises 



at once from the receptacular 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- the 

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

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



* Les Bull, de I'Acad. Roy. de Bruxelles, t. xvii., p. i., p. 415. 



Fig. 68.— Flower and leaf of 

 Musscenda. 



