270 Male-Sterility in Flax 



the ground, turning upward as flowering begins, and finally 

 standing more or less erect. 



2. The style is very pale in colour, and when the petals of an opening 

 flower are pulled off it projects well above the sepals, which are 

 perhaps slightly shorter than those of ordinary flaxes. But like 

 other forms of usitatissimum the variety is definitely homostyled, 

 the tops of the anthers just reaching beyond that of the stigma. 



3. It is very late in flowering, about 10 days later than any other 

 variety that we have. 



In other respects there is nothing special to note. The capsule and 

 seeds are of the ordinary size, not large as those of our oil-flaxes are. 



The first crosses were made in 1916 by Miss M. Michell of Cape 

 Town, who fertilised the procumbent with pollen from a tall white- 

 flowered fibre-flax. The object of this cross was to study the genetics of 

 height. Though from the extraordinary uniformity in height character- 

 istic of pure lines of flaxes these plants seem well adapted for such 

 work, the distribution of height in F. is complicated, all intergrades 

 occurring, with indications of segregation so imperfect that useful results 

 could only be obtained by measurements on a very large scale continued 

 through several generations. Much work of this kind has been carried 

 out on which we may publish a report later, but at present it must 

 suffice to say that though segregation in respect of height occurs, and 

 though the parental types, both procumbent and tall, reappear in F^, 

 they are rare, and the height-curves of these families show no obvious 

 dimorphism. 



The purpose of the present paper is to give the facts respecting the 

 behaviour of a male-sterile form which appeared in F<, in 1918. F^ is 

 erect and intermediate in height, and in colour also (as T, Tammes 

 found ^ in crosses between blue and white flaxes, and as we have also 

 often seen in other cases). In F.^ Miss H. Garlick, who was then in 

 charge of these experiments, observed certain plants, both blue, white 

 and intermediate in colour, which had flowers with reduced petals, as a 

 rule scarcely opening at all. In these flowers the anthers are more or 

 less completely aborted. A row of such plants growing beside a row of 

 normally flowered flaxes is shown on PI. XXVI, together with photo- 

 graphs of drawings of the normal and of the abnormal flowers in 

 various stages. 



1 Tammes, T., Rec. Trav. hot. Neerl., 1911, viii. pp. 264-5. 



