METAMORPHOSES OF INFLORESCENCES AND FLOWERS. 97 



not the petaloid calyx, but an enlargement of the corolla, which renders 

 the corymb conspicuous. In the garden form all the flowers have 

 enlarged corollas, by the sacrifice of the essential organs. Hence the 

 globular mass of flowers is now of no use to the plant at all. 



In some few plants the corolla has been known to bear abortive anthers. 

 Such has occurred in Foxgloves, Campanula, and Begonias. There may 

 be even an effort to produce or convert a petal into a carpel with ovules. 

 Begonias not infrequently exhibit various kinds of such malformations, 

 but they are always abortive. 



A large number of plants have flowers which show an entomophilous 

 ancestry, but are now in a state of degradation, having become self -fertilis- 

 ing and far more fertile than was their previous condition. Under this 

 changed condition the corolla is greatly reduced or has vanished. 

 Shepherd's Purse is a case of the first ; cleistogamous flower-buds of violet, 

 the second. Such degradations may be regarded as metamorphoses into 

 rudimentary organs. 



Stamens. 



Useful Changes. — The change from stamens to petals has laid the 

 foundation, as it were, for the whole floral world. The first flowers, as 

 far as we know, had no corolla nor coloured calyx. The Gymnosperms 

 certainly preceded both Dicotyledons and Monocotyledons ; and if exist- 

 ing forms of Gymnosperms have retained their primitive and ancestral 

 characters, nothing but yellow anthers existed to tell us both what was 

 the primitive colour, other than green, and what was the origin of petals. 

 That stamens of Gymnosperms originated out of green scales appears 

 revealed in such types as Cypress and Juniper ; while, turning to ordinary 

 flowering plants of the above-named classes, we seem to see the process of 

 petal-making at work in such plants as Water-lilies and Cannas. 



In the former, as the filament broadens, the anther- cells become 

 arrested, till complete petals are formed, in tracing them from within out- 

 wards, as may be readily seen in dissecting the flowers of the Water- 

 lily. 



In Canna all stamens are petaloid with the exception of one. 



As another useful change, we find the filaments broadening in 

 Atragene, forming quasi petals, but really destined to secrete honey. 



In several other members of the Banunculacece, it is the anthers which 

 have undergone a change and become converted into honey- secreting 

 nectaries, as may be well seen in the Winter Aconite and Hellebore. In 

 the Buttercup one half of the anther constitutes a petal, the other half 

 remains as a minute flap at the base. Between the two is the honey- 

 secreting surface. Besides the Hellebores, in the Aconite, Larkspur, 

 and Columbine the anthers have become variously spurred nectaries. 



Useless Changes. — Double flowers are usually composed of metamor- 

 phosed stamens and carpels, coupled with a great multiplication of their 

 number. Thus a Wallflower has normally six stamens and two carpels, 

 but a double flower of this plant may have more than fifty petals. 



In such flowers, whenever all sexuality is lost the doubling is of no 

 utility to the plant itself. 



This kind of doubling is mostly the result of the formation of petals 



n 



