1926] Bahcocl'-Lesley : Chromosomes and Taxonomic BelationsJiips 321 



Sec. X. Youngia Cass.* 



Distinct from preceding section in the small few-flowered (8-15) 

 heads. Stem few-leaved; involucre in mature fertile heads little 

 changed. Pappus readily deciduous. Fig. 6, v, v'. 

 C. japonica (L) Benth. 



Sec. XI. Catonia Much.* 



Involucre imbricate, often black hairy; outer bracts shorter 

 but at least half as long as inner bracts and forming no distinct 

 outer calyx, in mature fertile heads flat and unchanged. Fig. 6, 

 w, X,; fig. 7, y. 

 C. sibirica L., aurea (L) Cass., tlattarioides Vill. 



We shall first discuss Hoffmann's grouping of the twenty-one 

 species now before us, and then suggest a more natural grouping, in 

 order that the cytologic data to be presented may be more intelligently 

 considered. It will be noted that the genus, as treated by Hoffmann, 

 is divided into three subgenera but without designating them as such. 

 The first consists of the monotypic section, Ceramiocephalum ; the 

 second (a) contains three sections all characterized by having fruits 

 wdth definite beaks; and the third (&), comprising the remaining 

 seven sections, contains species none of which have manifestly beaked 

 fruits. It was long ago pointed out (Bischoff, 1851) that all degrees 

 of development of the beak are found in group (a), while some of the 

 species included in group ( h ) have fruits with very short or obscurely 

 developed beaks. But this seems to be generally looked upon as 

 merely part of the evidence of relationship within the whole group 

 and as part of the argument for treating it as a single genus. 



Section I is set apart from all the other species, probably justifiably, 

 but as we have not yet been able to work with living material of this 

 interesting species, it is unnecessary to give it further consideration 

 at present. 



Subgenus (a), on the basis of fruit characters alone, would be 

 better rearranged as follows : 



Sec. II. Fi'uits large, the inner ones 10-18 mm. long. 



C. alpiiia, foetida rubra (cf. figs. 1 and 2). 

 Sec. III. Fi'uits small, all alike, the inner ones 5-8 mm. long. 



C. bursifolia, setnsa, taraxacifolia (cf. fig. 3, d, e, g). 

 Sec. IV. Fruits small, of two shajies, marginal ones winged. 



C. aspera (cf. fig. 3, h, h'). 



Furthermore, the above rearrangement is not inconsistent with 

 other jnorphologieal characters of diagnostic value. This is especially 

 interesting in connection wdth the cytological evidence, the species 



* Described as a genus. 



