Leaf Definition

The ax leaf describes the body organ that forms the main lateral appendage top top the stem that vascular plants. In general, leaves are thin, flat organs responsible because that the photosynthesis of the plant. Back photosynthesis frequently only wake up on the upper surface of the leaf, it can happen on both political parties in some plant species. Pipeline are frequently comprised of a distinct upper and lower surface, stomata for gas exchange, waxy coating, hairs, and venation. Each side of the sheet differs in concerning the level to which these attributes are expressed. Although pipeline are typically located above ground, some species have pipeline which reside underground (e.g., pear scales) or underwater (e.g., aquatic tree species). Moreover, the leaves of some plants might not be associated with photosynthesis (e.g., cataphylls). Leaves are generally oriented on a tree to protect against blocking the sunshine of the leaves positioned underneath.

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Function that the Leaf

As one of the most essential constituents that plants, leaves have actually several crucial functions:


The primary duty of the leaf is the conversion of carbon dioxide, water, and also UV light into sugar (e.g., glucose) via photosynthesis (shown below). The basic sugars formed via photosynthesis are later processed right into various macromolecules (e.g., cellulose) required for the development of the plant cell wall surface and other structures. Therefore, the leaf have to be highly dedicated to incorporate the carbon dioxide, water, and UV light for this process. Carbon dioxide is diffused native the environment through dedicated pores, termed stomata, in the outer layer that the leaf. Water is directed to the pipeline via the plant’s vascular conducting system, termed the xylem. Leaves are orientated to ensure maximal exposure to sunlight, and are frequently thin and also flat in form to permit sunlight to pass through the sheet to with the chloroplasts, i m sorry are devoted organelles that carry out photosynthesis. As soon as sugar is developed from photosynthesis, the leaves function to carry it down the tree via dedicated structures called the phloem, which run in parallel to the xylem. The sugar is frequently transported to the roots and shoots that the plant, to assistance growth.



Some pipeline have also evolved defense instrument to stop being consumed or damaged. Part examples incorporate the spines that cacti, cones of gymnosperms, respectively. In addition, hairs discovered on leaves stop water lose in dry climates and also sting animals that detour herbivores (e.g., Urticaceae). Moreover, the waxy coatings found on leaves serve to protect against water loss, rain, and also forms the contamination. Oils and also other secreted substances also detract from being consumed through herbivores.

Types of Leaf

In general, the types of leaf have the right to be divided into six major types, although there are likewise plants with highly specialized leaves:

Conifer Leaf

Conifer leaves are needle-shaped or in the form of scales. Conifer leaves are typically heavily waxed and also highly adjusted to colder climates, i ordered it to dispel snow and also resist freeze temperatures. Part examples include Douglas firs and also spruce trees. The images below illustrate this type of leaf.


Microphyll Leaf

Microphyll pipeline are characterized by a single vein the is unbranched. Back this form of sheet is plentiful in the fossil record, couple of plants exhibit this kind of sheet today. Some examples incorporate horsetails and clubmosses. The image listed below illustrates this type of leaf.


Megaphyll Leaf

Megaphyll leaves are defined by multiple veins that deserve to be extremely branched. Megaphyll pipeline are vast and flat, and also generally comprise the foliage of most plant species. The image listed below illustrates this kind of leaf.


Angiosperm Leaf

Angiosperm leaves room those found on flowering plants. These leaves are identified by stipules, a lamina, and also a petiole. The illustration listed below shows an instance of one angiosperm leaves.



Fronds room large, split leaves characteristics of ferns and palms. The blades can be singular or divided into branches. The image below presents an instance of a frond.


Sheath Leaf

Sheath leaves are usual of grass varieties and monocots. Thus, the leaves are long and also narrow, v a sheathing surrounding the stem at the base. Moreover, the vein framework is striated and each node contains only one leaf. The image below presents an instance of a sheath leaf.



1. The primary duty of a leaf is: A. Water evaporation for cooling B. Photosynthesis C.

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provide shade come the shoot and root structures of the plant D. Transpiration