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Outlines of Lessons in Botany, Part I; from Seed to Leaf by Jane H. Newell
page 73 of 105 (69%)
2. _Vernation_. This term signifies the disposition of leaves in the bud,
either in respect to the way in which each leaf is folded, or to the
manner in which the leaves are arranged with reference to each other.
The pupils have described the folding of the leaves in some of their
specimens.

In the Beech, the leaf is _plicate_, or plaited on the veins. In the Elm,
Magnolia, and Tulip-tree, it is _conduplicate_, that is, folded on
the midrib with the inner face within. In the Tulip-tree, it is also
_inflexed_, the blade bent forwards on the petiole. In the Balm of Gilead,
the leaf is _involute_, rolled towards the midrib on the upper face.

Other kinds of vernation are _revolute_, the opposite of involute, where
the leaf is rolled backwards towards the midrib; _circinate_, rolled from
the apex downwards, as we see in ferns; and _corrugate_, when the leaf is
crumpled in the bud.

[Illustration: FIG. 20.--Branch of Norway Spruce.]

In all the trees we have studied, the leaves simply succeed each other,
each leaf, or pair of leaves, overlapping the next in order. The names of
the overlapping of the leaves among themselves, _imbricated, convolute,
etc_., will not be treated here, as they are not needed. They will come
under _æstivation_, the term used to describe the overlapping of the
modified leaves, which make up the flower.[1]

[Footnote 1: Reader in Botany. VIII. Young and Old Leaves.]


3. _Phyllotaxy_. The subject of leaf-arrangement is an extremely difficult
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