leaf

The definition of a leaf is a part of a plant or tree attached to the stem or branches.

Categorizing Leaves

Complexity - Simple leaves are those which the leaves go outward, and they are all in a unified shape. compound leaves, you will notice that they appear to be like multiple leaves that have been combined together.

Stem - Leaves with stems on them are known as petiolated. If a leaf does not have a stem on it, then are known as sessiles.
Shape - Ovate leaves are shaped like eggs, and they have sharp, pointed ends. Cordate leaves are shaped like hearts. Lanceolate leaves tend to look like lances. Elliptic leaves are thin and egg-shaped. Hastate leaves are comprised of three connected leaves which stretch out from one main point. Acicular leaves are long, needle-like, and have pointed tips. Linear leaves are like acicular leaves, except they have rounded ends.
Edge - Lobed leaves have lobes on them that point out at random intervals. Dentate leaves, which come from the Latin word for "teeth," have little teeth-like markings along the edges of the leaf. Serrate leaves are similar to dentate leaves, except the little teeth are much closer together. Sinuate leaves have curved edges with waves or bumps along the sides. Leaves with smooth edges are known as "entire edges."

The leaf's color comes from the three natural pigments that are present in the plant’s cells structures - chlorophyll (green color), carotenoid (orange, yellow and brown colors) and anthocyanin (red, purple and crimson color).
During the fall, less chlorophyll is produced since the days are shorter and cooler. The rate of chlorophyll production decreases, fading the green color and the leaves produce vibrant anthocyanin pigments.
Red and yellow pigments will soon start to disintegrate and decompose once the leaf falls to the ground.

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(noun)

An example of a leaf is the part of the tree that is green in the summer and may change colors and fall off of the tree before the start of winter.

See leaf in Webster's New World College Dictionary

noun pl. leaves

any of the flat, thin, expanded organs, usually green, growing laterally from the stem or twig of a plant: it usually consists of a broad blade, a petiole, or stalk, and stipules and is involved in the processes of photosynthesis and transpiration
in popular usage
1. the blade of a leaf
2. a petal
leaves collectively: choice tobacco leaf
a design resembling a leaf, used as an ornament in architecture
a sheet of paper, esp. as part of a book, with a page on each side
1. a very thin sheet of metal; lamina
2. such sheets collectively: covered with gold leaf
1. a hinged section of a table top, forming an extension when raised into place
2. a board inserted into a table top to increase its surface
a flat, hinged or movable part of a folding door, shutter, etc.
☆ one of a number of metal strips laid one upon another to make a leaf spring

Origin: ME lefe < OE leaf, akin to Du loof, Ger laub < IE base *leubh-, to peel off, pull off > Lith lupù, to skin, pare off

intransitive verb

transitive verb

turn the pages of

Related Forms:

See leaf in American Heritage Dictionary 4

noun pl. leaves leaves (lēvz)

A usually green, flattened, lateral structure attached to a stem and functioning as a principal organ of photosynthesis and transpiration in most plants.
A leaflike organ or structure.
a. Leaves considered as a group; foliage.
b. The state or time of having or showing leaves: trees in full leaf.
The leaves of a plant used or processed for a specific purpose: large supplies of tobacco leaf.
Any of the sheets of paper bound in a book, each side of which constitutes a page.
a. A very thin sheet of material, especially metal.
b. Such leaves considered as a group: covered in gold leaf.
A hinged or removable section for a table top.
A hinged or otherwise movable section of a folding door, shutter, or gate.
One of several metal strips forming a leaf spring.