Testing Farm Seeds. . 387 



TESTING FLAXSEED. 



Properly cleaned flaxseed should be praetically free from impuri- 

 ties, thus showing a purity of nearly 100 per cent. The viability should 

 reach 99 per cent or higher in two or three days. Both domestic and im- 

 ported seed are in the market. Poorly cleaned grades contain many 

 kinds of weed seeds which, in general, include most of those found in 

 millet seed and in wheat. In a test of flaxseed especial attention should 

 be given to the discovery of seed of flax dodder. As shown in figure 12, 

 some of these dodder seeds are double and thus fail to pass a sieve which 

 will remove most of the single seeds. Fairly well-cleaned lots of flax are 

 thus likely to contain these double seeds of dodder. ]\Iuch of the im- 

 ported flaxseed contains seed of flax dodder. The very destructive nature 

 of this dodder justifies every effort to prevent the introduction of its 

 seed. Seed of false flax (fig. 17, p) is a common noxious impurity which 

 should be avoided. 



TESTING WINTER RAPE SEED. 



Popular tests of rape seed are not likely to be wholly satisfactory be- 

 cause of the difficulty in identifying with certainty the seeds of the dif- 

 ferent kinds of rape and the closely allied mustard weeds. Seed of the 

 more important winter, or Essex, rape may generally be recognized by 

 the relatively large size of the individual seeds (somewhat larger than 

 those of summer rape or of turnip), by their steel-black color, and their 

 roundness, allowing them to roll readilj^ on a plane surface. Summer 

 rape seeds are mostly smaller, consisting of a mixture of black and red- 

 dish seeds, some of the black seeds being distinctly pitted, or nearly all 

 the seeds reddish. Some lots of seed, particularly of summer rape, are 

 adulterated with seed of English charlock (fig. 17, t). As a rule, the 

 charlock seeds may be distinguished 1\v their smaller size, more nearly 

 spherical form, their smoother surface and by the presence of mature 

 reddish or brown seeds with the black ones. Some lots of rape seed are 

 heavily adulterated with seed of Indian mustard (fig. 18, a) . These seeds 

 are readily recognized by their uniformly reddish-brown color and by the 

 netted or pitted surface as seen under a magnifier. The purity of winter 

 rape should be 99 per cent or higher, the viability as high under a test 

 of two or three days' duration. A miscellaneous series of weed seeds, 

 most of which are previously described and figured, is likely to appear in 

 poorly cleaned grades of rape seed, particularly the summer variety. 



