Fig. 2.—No Two Leaves are Alike.
Variation, or differences between organs and also between organisms, is one of the most significant facts in nature.
Suggestions.—The first fact that the pupil should acquire about plants is that no two are alike. The way to apprehend this great fact is to see a plant accurately and then to compare it with another plant of the same species or kind. In order to direct and concentrate the observation, it is well to set a certain number of attributes or marks or qualities to be looked for. 1. Suppose any two or more plants of corn are compared in the following points, the pupil endeavouring to determine whether the parts exactly agree. See that the observation is close and accurate. Allow no guesswork. Instruct the pupil to measure the parts when size is involved.
(1) Height of the plant.
(2) Does it branch? How many secondary stems or “suckers” from one root?
(3) Shade or colour.
(4) How many leaves.
(5) Arrangement of leaves on stem.
(6) Measure length and breadth of six main leaves.