26 



PLANT BIOLOGY 



sheath, c, m ; the epicotyl has grown to / ; the first plu- 

 mule-leaf is at c. 



In studying corn or other fruits or seeds, the pupil should 

 note how the seeds are arranged, as on the cob. Count the 



rows on a corn cob. Odd or 

 even in number ? Always the 

 same number? The silk is 

 the style : find where it was 

 attached to the kernel. Did 

 the ear have any coverings ? 

 Explain. Describe colors and 

 markings of kernels of corn ; 

 and of peas, beans, castor 

 bean. 



Gymnosperms. The seeds 

 in the pine cone, not being 

 inclosed in a seed-vessel, 

 readily fall out when the cone 

 dries and the scales separate. 

 Hence it is difficult to find 

 cones with seeds in them after 

 autumn has passed (Fig. 29). 

 The cedar is also a gymno- 

 sperm. 



Remove a scale from a 

 pine cone and draw it and 

 the seeds as they lie in place 

 on the upper side of the scale. 

 Examine the seed, preferably with a magnifying glass. Is 

 there a hilum ? The micropyle is at the bottom or little 

 end of the seed. Toss a seed upward into the air. Why 

 does it fall so slowly ? Can you explain the peculiar whirl- 

 ing motion by the shape of the wing ? Repeat the ex- 



FIG. 28. GERMINATION is COM- 

 PLETE. 



p, top of epicotyl ; 'o, plumule-leaf; 

 nt, roots; c, lower roots. 



