Heteromorphism in Helianthemum 



By John Hendley Barxhart 



It is no new discovery that in some of our common North 



American species of Helianthemum the flowers are of different 



forms on the same plant. In 1824, Dunal, in the first volume of 



DeCandolle's Prodromus, described 112 species of Helianthemum 



known to him ; only seven of them were American, and of these he 



constituted the section Lechioides., but no mention is made of the 



occurrence of heteromorphism. In the same year, however, Elliott 



(Bot. S. C. & Ga. 2 : 5), at the end of his description of H. corym- 



bosum, remarks : " Frequently in a corymb, one or two flowers rise 



conspicuously above the rest, and the capsules then become much 

 larger." 



Sweet's great illustrated work on the Cistineae was published 

 in parts from 1825 to 1830, and it is easy to trace through its 

 pages the development of the author's ideas about heteromorphism 

 in the American species of Helianthenmm. Under No. II, H. 

 polygalaefolium, published in November, 1825, he says: "we have 

 not seen any perfect flowers of H. Brasiliense, as it did not bloom 

 till autumn, and the flowers were all apetalous, which was also the 

 case with the autumn flowers of the present species, and all the 

 other species of this section that we have had an opportunity of 

 examining this season ; the apetalous flowers all produce perfect 

 seeds, but we cannot understand the reason of their producing per- 

 fect flowers only in summer." 



Under No. 21, H. Canadense (May, 1826): "Its handsome 

 flowers are produced in abundance in July and August ; after that 

 time it continues to bloom and ripen seeds plentifully until October ; 

 but the flowers after August are all without petals, the calyx and 

 capsules are also smaller and of a different form from those pro- 

 duced by the flowers with petals ; this is also the case with H. 

 polygalaefolium and Brasiliense, and we expect with the whole of 

 this section." Under No. 43, H. Brasiliense (March, 1827) : " the 

 present drawing was taken last May, the first time that it produced 

 perfect flowers ; those that were produced the preceding autumn 



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