82 NATURE STUDY AND AGRICULTURE 
5. The flower of a legume. — (a) Take the flower of a sweet pea, a 
garden pea, or a bean. Note the general form — the large upper petal, 
two smaller ones at the side, and the two smallest at the bottom fastened 
together into a boat-shaped object. Now observe the smaller: flowers 
of clover, alfalfa, and other legumes, and notice that they have the same 
form. Bya little practice you can become quite skillful in distinguishing 
legumes in this way. 
(b) Remove the petals of the pea or bean and notice the stamens. 
How many are there? Are they all united? If not, how many are free 
from the rest? Note the form of the pistil— its resemblance to the 
mature pod. 
(c) When the pea or bean is ripe, notice how the pod splits open on 
both seams and exposes a single row of seeds. Now find well-grown pods 
on clover, alfalfa, and other legumes and note that they have the same 
structure as the larger pods of peas and beans. The trained observer 
can safely classify a plant as a legume by the pod alone. 
6. The nodules on the roots of legumes. — Dig up a well-grown garden 
pea, white clover, or other legume and look for small whitish growths on 
the smaller roots. By a little practice you will learn to find them very. 
easily. Explain the part that these nodules play in the enrichment of 
the soil. 
7. The structure of a composite flower. — Take either a cultivated 
or a wild sunflower and cut it as shown in the picture on page 77. You 
will easily see that the bulk of the sunflower is really made up of scores 
of perfect little flowers with a yellow, tubular corolla having five points 
on its rim. With the aid of a pin tear away this corolla and try to find 
the five stamens and the pistil with its long style, its two stigmas above, 
and its ovary or seed at the bottom. Examine the petal-like objects 
called “rays” on the margin of the sunflower. Notice that the ray has 
five little points at the end and is slightly rolled up at the base, indicating 
that it has been developed from a tubular corolla by splitting it down 
the side, flattening it out, and lengthening it. The remnant of the ovary 
at the bottom may also be recognized, though in the sunflower it cannot 
develop into a seed because there is no stigma. 
Now examine other composite flowers and note resemblances and 
differences as compared with the structure of the sunflower. After a 
little practice you should be able to distinguish a composite flower at 
sight. What is the difference between such a flower and a clover blossom? 
