Testing Farm Seeds. 



351 



plant, appears as a small but distinct ring. (See figs. 22 and 26.) In the 

 more or less spherical seeds of the vetches the scar is an oval, wedge- 

 shaped, or slender spot on the curved surface. (See fig. 32.) In this- 

 class of seeds the scar is an impprtant mark of distinction. In several of 

 the small-seeded kinds of leguminous plants occasional pods appear even. 

 in well-cleaned lots of seed. (See figs. 22, 23 and 27.) 



Most of the grass seeds, also oats and barley, appear "in the chaff,"' 

 that is, the grains or kernels of the seed, illustrated by the kernels of 

 wheat and the hulled seeds of timothy, are usually covered by the dried 

 chaffy flower scales. (See fig. 16.) The difference in size, form and 

 structure of this chaff marks the different kinds of grass seeds. 



Seeds of the Grasses. — Grass seeds are produced in clusters (spike- 

 lets). Some clusters contain several seeds arranged along a common axis 

 (rachilla). At maturity the clusters break apart, each seed carrying a 



piece of the cluster axis (rachil- 

 la segment). Such seeds have 

 two chaff scales, one (the lem- 

 ma) larger than the other (the 

 palet or palea). (See fig. 16.) 

 Examples of this class of grass 

 seeds are found in orchard 

 grass, meadow fescue, rye-grass^ 

 brome-grass and in the blue- 

 grasses. (See figs. 10 and 9.) 

 In another class of grasses each 

 cluster contains but a single 



Fig. 16. — A spikelet and florets ("seeds") of 

 Kentucky bluegrass : a, Spikelet as it ap- 

 pears at maturity ; b, the same having the 

 florets spread apart, showing the jointed 

 rachiUa; c, back vie^v of a floret, show 



ing the lemma (1) ; d, front view of the seed which, therefore, has no ra- 



floret, showing the edges of the lemma 

 (1), the palet (2), and the rachilla seg- 

 ment (3) ; e, the grain or kernel of the 

 seed. 



chilla segment. The seeds of 

 broom corn (or grain) millet 

 are a good example of this class, the seed scales, lemma and palea being 

 hard, smooth and shining. (See fig. 31, a.) Part of the seed of foxtail 

 millet, Japanese millet, and the foxtail weeds differs structurally from 

 the last only in being covered by two or three additional chaffy scales, 

 which constitute the "outer chaff." (See fig. 31, b and c.) 



These features of form and structure are easily recognized when 

 representative seeds come to be compared under a magnifier, and it is ad- 

 visable to understand them in making tests of clover and grass seeds, 

 because the element of certainty is essential to satisfactory results. 



