EXERCISE XXXIII. 

 CHARACTERISTICS OF LEGUME SEEDS. 



Supplies for a Laboratory Section of Twelve. Twelve small vials of each of the following: crimson clover, 

 common alfalfa, burr clover, yellow trefoil, white sweet clover, white clover, alsike clover, rea clover, and smal" 

 yellow annual sweet clover. "Prepared Mixtures of Legume Seeds." Twelve tripod magnifiers. 



INTRODUCTION. As has been said in the introduction to the study of grass "seeds, s 

 legumes are one of the two great botanical families which include most of our common and 

 valuable forage crops. Legumes, being a very different family from the grasses, have seeds 

 which are very different in structural points. A study of the cereals made a good preparation 

 for work with the so-called "seeds" of forage grasses, but we have had no such preparatory 

 study to help us with legumes. We must, therefore, find and study the peculiarities of the 

 legume seed. 



From Exercise XIII, Part A, you have at least some idea as to the gross structure of 

 the legume seed. A careful examination of the small leguminous seeds before you will prove 

 that these seeds are essentially like the seed of a bean and that they have a number of 

 characteristic structural points in common. A more careful study will show that these com- 

 mon structural points vary considerably as between one species of legume and another. It is 

 through study of these points ("scar," "nose," "notch," and "groove," together with such 

 things as shape, size, skin texture, color and odor) that we become able to identify with con- 

 siderable certainty the seeds of the more common small-seeded legumes. 



1. Scar. Under a small lens observe that each seed has a "scar." The scar is sit- 

 uated on one edge of the seed — usually in a "notch" near the middle. Because of its large size 

 and the surrounding ring of reddish color, the "scar" is very prominent in crimson clover. 

 The botanist calls the "scar" the "hylum.' What is your explanation of the "scar"? 



2. Nose. It will be observed that one end of the seed of the average small-seeded legume 

 is wider than the other. At a point very near one end of the "scar," where this broader end 

 more or less suddenly narrows on one side to meet the narrower end, there is, in effect at 

 least, a sort of projection. This projection in some seeds, red clover for instance, suggests 

 the thumb of a catching mitt, or boxing glove. 



Botanists call this projection "the free end of the radical." Practical seed analysts are 

 more apt to call it the "nose" or the "beak." In some legumes, sweet clover, for instance, 

 the "nose" is rather large, but not very sharp or abrupt. In others, red clover, for instance, 

 the "nose" is quite variable and may be rounded, abrupt, or even hooked. Which seed has a 

 small but abruptly projecting "nose" of the "pug" type? 



3. Notch. The "notch" in which the scar is situated is a depression in the edge of the 

 seed. The notch is, in part at least, formed on one side by the more or less abrupt ending of 

 the "point of the radicle." 



(a) In which two is the rather deep, but not very abrupt notch near the middle of one 

 end? 



(b) In which two is the notch rather prominent and near to the corner of one end? 



(c) In which one is the notch rather deep, abrupt, and very near the middle of one side? 



(d) In which one is such notch as exists formed mainly by the abrupt projection of the 

 "nose" or "free end of the radicle"? 



(e) In which three is such notch as there is nearly in the middle of one side? 



4. Groove. Note that there is normally a furrow-like depresssion or "groove" which be- 

 gins in the notch and runs along side, and nearly parallel to one edge. This furrow or groove 

 extends toward one end of the seed, but usually disappears before reaching it. The groove 

 divides the seed into two parts of different size and shape. There is a marginal roll or ridge 

 lying between the groove and the edge alongside of which the groove runs. It is the outer- 



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