590 Bar:; hart : Heteromorphism in Helianthemum 



being all apetalous, as are the autumn flowers of all the species of 

 this section that we have had an opportunity of seeing ; but those 

 apetalous flowers produce as perfect seeds as the complete flowers. 



Under No. 99, H. Carolinianum (July, 1829), no mention of 

 heteromorphism is made, although it is placed in the section 

 Lechioides ; yet under No. 1 10, H. glomeratum (January, 1830), is 

 given the following broad generalization : " Like all the other 

 American species that we have yet seen or heard of, it belongs to 

 the section Lechioides of DeCandolle ; all the species of which pro- 

 duce flowers with petals, in the spring and early in summer, whereas 

 all those that are produced in autumn, which are much more numer- 

 ous, are all apetalous. " 



Spach (Ann. Sci. Nat. II. 6: 370. D. 1836) segregates 

 all the American species formerly referred to Heliantliemum, ex- 

 cept H. Carolinianum, in a new genus Heteromeris, characterized 

 by the two kinds of flowers on each plant ; Torrey and Gray (FI. 

 N. Am. 1 : 151. 1838) correctly attribute heteromorphous flow- 

 ers to all their North American species except H. scoparium and 

 H. Caroliniamim ; and the investigation here reported shows that 

 of all the species since described from the same territory (Califor- 

 nia excepted) none is truly homomorphous. 



My attention was first called to this subject by finding an ap- 

 parently undescribed species of Helianthemum in Florida, which 

 upon examination proved referable to the heteromorphic group. 

 Yet its affinity was evidently with H. Nashii, which was originally 

 described as having the flowers alPalike, and this led to a careful 

 reexamination, first of the available material of H. Nashu, and 

 then of the other North American species. 



The most recent review of our species is to be found in Gray s 

 Synoptical Flora (i l : 189-191. 1895) where four species, H. 

 Canadense, H. majus, H. capitatum and H. corymbosum, are said 

 to have heteromorphous flowers, while five, H. arenicola, H. Nashu, 

 H. Carolinianum, H. scoparium and H. Greenei, are described with 

 the flowers homomorphous. H. arenicola and H. Nashu must 

 have been placed among the homomorphous species merely be- 

 cause of their original descriptions. Since the appearance of the 

 portion of the Synoptical Flora here referred to, an excellent new 

 species (//. Gcorgianuni) has been added (Chapman, Fl. So. U. 5. 



