Grade. 

 Date.. 



EXERCISE 36 

 WEED SEEDS 



Object. To identify some important weed seeds (Fig. 43) . 



Material. About twenty (or more if time is available) important weed 

 seeds. Part of these should be chosen because of their prevalence in the 

 locality and part of them because of their prevalence in commercial seed. 



v r 



FIG. 43. Mixture of weed seeds commonly found in low grade alsike clover seed: a, alsike clover; 

 b, white clover; c, red clover; d, yellow trefoil; e, Canada thistle; /, dock; g, sorrell; h, buckhorn; ?', rat-tail 

 plantain; k, lamb's quarter; I, shepherd's purse; m, mayweed; n, scentless camomile; o, white campion; 

 p, night-flowering catchfly; q, oxeye daisy; r, small fruited false flax; s, cinquefoil; /, two kinds of pepper- 

 grass; u, catmint; r, timothy; x, chickweed; y, Canada blue grass; z, clover dodder; 1, mouse-ear chickweed; 

 2, knot grass; ?, tumbling amaranth; 4, rough amaranth; -5, heal all; 6, lady's thumb. Enlarged (U. S. D. A.) 



Drawings. Draw each seed under the low power microscope and make 

 each drawing one mch the longest way. This rule will overcome the tendency 

 of many students to draw seeds natural size. If it is desired to indicate 

 relative size of the seeds, the class may number the largest seed No. 1, the 

 second largest No. 2, etc. Weed seed holders as shown in figure 37 

 are convenient. 



Identification. Examine numbered but unlabeled mixtures of the weed 

 seeds drawn above. Each mixture should contain three or four kinds of seeds. 



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