46 PRACTICAL COURSE IN BOTANY 



at the upper end of the hypocotyl, just above the point where 

 the cotyledons are attached ; this is the epicotyl, or part 

 above the cotyledons, here identical with the plumule ; does 

 it develop as rapidly as in the other seedlings you have ex- 

 amined ? 



46. Relation of parts in the seedling. Before leaving this 

 subject, it is important to fix clearly in mind the different 

 parts of the germinating seedling and their relation to both 

 the embryo from which they originated and the plant into 

 which they are to develop. The part labeled " hypocotyl " 

 in your sketches is all that portion of the embryo below the 

 point of attachment of the cotyledons. In germination its 

 upper part will become the stem, and in the embryo con- 

 stitutes the caulicle, or stemlet, while its lower part, from 

 which the root will develop, is the radicle, or rootlet ; hence 

 the term " hypocotyl " includes both the future root and 

 stem. The plumule is that part of the embryo between the 

 cotyledons and above their point of attachment to the caulicle. 

 It is the upward growing point of the young plant, and hence 

 the place of attachment of the cotyledon is the first node, or 

 point of leaf origin, on the stem. 



The epicotyl, in contradistinction to the hypocotyl, is all 

 that part of the plant above the insertion of the cotyledons. 

 Before germination it is identical with the plumule. As the 

 seedling grows, the epicotyl advances its growing point by 

 adding new nodes and internodes, as the spaces between the 

 successive points of leaf insertion are called. 



47. Botanical terms. As the prefixes hypo and epi are 

 of frequent occurrence in botanical works, it will aid in 

 understanding their various compounds if you will remem- 

 ber that hypo always refers to something below or beneath, 

 and epi, to something over or above. With this idea in mind 

 you will see that botanical terms are a labor-saving device, 

 since it is much easier, in making notes, to use a single de- 

 scriptive word than to write out the long English equivalent, 

 such as " the part under (or over) the cotyledons," 



