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 catyledons, 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. — Lefore 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 emhryo 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 plart 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 ept, 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.” 
