124 



W. H. GILBURT ON THE 



calyx in the Composita?, Dr. Masters refers in his paper to the 

 various opinions held by botanists of authority upon the subject, and 

 says, " For my own part, I am disposed from the facts above- 

 mentioned, and from my examination of a large number of teratolo- 

 gical specimens, to agree with those who, like Buchenau and Warm- 

 ing, are of opinion that at present Composites have no true calyx, 

 or only traces of it, and that the pappus consists of mere appendages 

 or outgrowths not referable to distinct sepals. Buchenau suggests 

 that pre-historic Composites had a five -leaved calyx, which has 

 become effaced as time has rolled on, from the pressure exerted by 

 the densely packed flowers." Then, after citing the opinions of 

 Lund and Hofmeister, that each pappus hair, or scale, represents a 

 sepal ; and pointing out that Warming, in opposition to this 

 theory, shows that they do not correspond in position, nor agree as 

 to period of development with sepals, and that the slight rim which 

 forms beneath the corolla should be regarded as the true calyx, Dr, 

 Masters says, " In all these points I am disposed to concur with the 

 Danish naturalist (Warming), who further refers these organs to 

 Trichomes rather than to Phyllomes, on anatomical grounds, upon 

 the validity of which I am in no position to offer an opinion." 



In Helianthas we have two series of structures which have been 

 referred to calyces by different authorities, viz., Trichomes, or hairs, 

 which are found at the base of the corolla, and the two scale-like 

 leaflets which surmount the ovary. 



Duchartre appears to have been the first to observe and refer the 

 former to the calyx, and he describes their development, first as a 

 ring of tissue, which afterwards, for the want of parenchyma, splits 

 up into plates and eventually into hairs composed of a single series 

 of cells. In this developmental history I cannot help thinking he 

 was mistaken, as after a very careful examination of a large number 

 of florets in all stages of development I have not been able to see 

 them in any other form than that which he describes as the final 

 one. Moreover, they do not occupy one plane, but extend over a 

 considerable space ; they each have their origin in a single epidermal 

 cell, and are but the termination, though more fully developed, of a 

 series which extends upward from the base of the ovary. Again, if 

 we regard them as representing the calyx, the difficulty as to 

 retarded development is greatly increased (this Duchartre himself 

 points out), as they are not seen till the ovule is well advanced. 

 From these considerations it would appear that they are only refer- 

 able to Trichomes. 



