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  Croptilon Raf. 

Scratchdaisy

A small genus of three annual species native to the southeastern U.S. with a center of diversity in eastern Texas.  The genus includes an chromosomal aneuploid series from x=7 to x = 4 (Smith 1966 ).  It has been treated as Haplopappus sect. Isopappus (Hall 1928; Smith 1965 Rhodora 67: 217-238.), but phylogenetically it belongs in subtribe Chrysopsidinae, not subtribe Machaerantherinae.  In a cladistic study by Semple and Tebby (1999), Croptilon was closely related the Braduria and Heterotheca.  DNA sequence data also place it close to Heterotheca (Luc Brouillet, pers. comm.).

Smith (1981 Sida 9: 59-63) treated the taxa in Croptilon and proposed the following nomenclature:

• C. hookerianum var. graniticum (x = 7)
• C. hookerianum var. hookerianum (x = 6)
• C. hookerianum var. validum (x = 5)
• C. rigidifolium (x = 5)
• C. divaricatum (x = 4)

Croptilon divaricatum (Florida), C. hookerianum var. hookerianum (Texas, cult. WAT), and C. rigidifolium (Carr 21953 TEX)

Last update 24 October 2005 by J.C. Semple            © 2005  J.C. Semple