12 E. B. Babcoc\ 



of the Cichorieae, the tribe which includes all species of the Com- 

 positae having only ligulate florets in the flowerhead. The largest 

 genus is Hieracium, with hundreds of species and thousands of 

 subspecies, varieties, and forms, the constancy of which (at least 

 of many) is made possible by some type of apomictic reproduc- 

 tion. In marked contrast with this condition in Hieracium is the 

 nearly complete absence of asexual reproduction in Crepis. A 

 few species are stoloniferous and certain others spread from root 

 sprouts, but apomixis is apparendy at a minimum and actually 

 has been demonstrated in only one species, C. tenui folia, which 

 is a peculiar species in other respects. (The occurrence of apo- 

 mixis is also suspected in certain American species with odd 

 chromosome numbers.) Next to Crepis in size is Lactuca, which 

 in its present vaguely defined state contains between seventy- 

 five and one hundred species. These largest genera, Hieracium, 

 Crepis, and Lactuca, are well differentiated, although there 

 are borderline species or sections as well as certain small inter- 

 mediate genera which are discussed below. The other larger 

 genera in the Crepidinae are Chondrilla, Taraxacum, Launea, 

 Sonchus, and Prenanthes. All these but the last are sharply dis- 

 tinguished from the three largest genera. Prenanthes, like Lac- 

 tuca, is at present rather vaguely defined. At any rate, both are 

 in need of thorough revision. Nevertheless, for purposes of the 

 present discussion it is possible to deal with them as well-known 

 groups. 



These four larger genera, Crepis, Hieracium, Lactuca, and 

 Prenanthes, include annual, biennial, and perennial herbs, a few 

 of the perennials being somewhat suffrutescent. The earlier 

 leaves usually form a rosette. The flower stems may be simple, 

 scapiform, and merely bracteate, or more or less branched with 

 few or many heads and with the cauline leaves more or less re- 



