2S2 BOTANICAL GAZETTE [October 



scintillans appeared as mutants, showing that the mutation coeffi- 

 cients for these three forms do not essentially differ from one 

 another. 



Stray mutations into cana have appeared in later years in 

 different cultures, as, for instance, in 1913 in those of 0. laevifolia 

 and 0. scintillans. Three mutations from O. pallescens will have 

 to be recorded in the pedigrees relating to this form. It seems 

 probable that cana mutants also have appeared in previous years, 

 but have not been distinguished from other narrow-leaved types, 

 of which there have always been quite a number in the larger cul- 

 tures. Many other mutations also have escaped observation 

 during a series of years until a single specimen developed into 

 a strikingly new type. 



I have cultivated 0. cana mostly as annuals, but in some 

 instances as biennials. In both cases the stature is the same as that 

 of 0. Lamarckiana, but in the annuals the stems are slender and the 

 fohage rather loose, whereas the biennials have thick and strong 

 stems with dense foHage. The leaves are narrow, with a shorter 

 blade and a longer petiole, and of a very striking gray color. The 

 flower buds are long and thin, contrasting sharply with those of 

 0. Lamarckiana and even more so with those of 0. pallescens and 

 0. Lactuca. The spike is less dense than in the parent species and 

 the fruits are more cylindrical and narrower, containing fewer seeds 

 (fig. 2) . In the flowering condition, as weU as in the stage of young 

 rosettes, the plants are now easily recognized, but at other periods 

 of their development it is often difficult to identify and count 

 them, some specimens showing their marks very clearly, but others 

 resembling more or less their Lamarckiana-]ik.& sisters. 



The easiest marks are afforded by the flower buds. Measured 

 the day before opening and with the tube and ovary, their size 

 varies, as a rule, from 75-80 mm., against 80-95 i^^^^ii- in 0. Lamarck- 

 iana cultivated under the same conditions; means 77.5 against 

 90 mm. The breadth, measured at the base of the conical part 

 above the tube, is only 7 mm. The 4 tips at the top of the bud 

 are more or less bent on one side, and this curious mark is so striking 

 that it is often the first which draws the attention to a stray 

 mutant of the cana type (fig. 2). The 4 lobes of the stigma are 



