idea, and believe it is better to let them first imbibe it unconsciously
in their study. Whenever their minds are ready for it, it will be readily
understood. The chief difficulty is that they imagine that there is a
direct metamorphosis of a leaf to a petal or a stamen.

Briefly, the theory is this: the beginnings of leaf, petal, tendril, etc.,
are the same. At an early stage of their growth it is impossible to tell
what they are to become. They develop into the organ needed for the
particular work required of them to do. The organ, that under other
circumstances might develop into a leaf, is capable of developing into a
petal, a stamen, or a pistil, according to the requirements of the plant,
but no actual metamorphosis takes place. Sometimes, instead of developing
into the form we should normally find, the organ develops into another
form, as when a petal stands in the place of a stamen, or the pistil
reverts to a leafy branch. This will be more fully treated under flowers.
The study of the different forms in which an organ may appear is the study
of _morphology_.


1. _Forms of Stems_.--Stems may grow in many ways. Let the pupils compare
the habits of growth of the seedlings they have studied. The Sunflower and
Corn are _erect_. This is the most usual habit, as with our common trees.
The Morning Glory is _twining_, the stem itself twists about a support.
The Bean, Pea and Nasturtium are _climbing_. The stems are weak, and
are held up, in the first two by tendrils, in the last by the twining
leaf-stalks. The English Ivy, as we have seen, is also climbing, by means
of its aërial roots. The Red Clover is _ascending_, the branches rising
obliquely from the base. Some kinds of Clover, as the White Clover, are
_creeping_, that is, with prostrate branches rooting at the nodes and
forming new plants. Such rooting branches are called _stolons_, or when