Pinnately-compound leaves have their leaflets arranged along the middle vein. The bumps protruding from the lower surface of the leaf are glandular trichomes.
Below the palisade parenchyma are loosely-arranged cells of an irregular shape.
Unlike hydrophytes, mesophytes have adapted to form a waxy cuticle since shortage in water supply could be a problem due to the unique niches of these plants. Leaves may be simple or compound.
Both layers of the mesophyll contain many chloroplasts. Spongy mesophyll cells also contain chloroplasts and photosynthesis occurs here too. However, in plants that grow in very hot or very cold conditions, the epidermis may be several layers thick to protect against excessive water loss from transpiration.
How is a leaf adapted for photosynthesis bbc bitesize
Figure 23 In xerophytes, it is common for plants to either have extremely small leaves, or even an absence of leaves . Bipinnately-compound double-compound leaves have their leaflets arranged along a secondary vein, which is one of several veins branching off the middle vein. Leaves are classified as either alternate, spiral, opposite, or whorled. Some leaves have a petiole, which attaches the leaf to the stem; leaves that do not have petioles are directly attached to the plant stem and are called sessile leaves. It produces a waxy layer, called the cuticle, which is not made of cells but is a waterproof barrier to prevent excessive evaporation through the hot upper surface of the leaf. These are the cells of the spongy parenchyma or spongy mesophyll. Simple and compound leaves: Leaves may be simple or compound. A thin shape A thin shape means a short distance for carbon dioxide to diffuse in and oxygen to diffuse out easily. The air space found between the spongy parenchyma cells allows gaseous exchange between the leaf and the outside atmosphere through the stomata. This layer consists of irregularly shaped cells with large air spaces between them allowing gas exchange diffusion between stomata and photosynthesising cells. The palisade cells have many chloroplasts in their cytoplasm and the box-like shape and arrangement of these cells ensures they are packed tightly together. The mesophyll is found between the upper and lower epidermis; it aids in gas exchange and photosynthesis via chloroplasts. In a compound leaf, the leaf blade is completely divided, forming leaflets, as in the locust tree. The waxy cuticle found on mesophytes is absent in underwater hydrophytes, since water loss is not a limitation for these plants, in contrast, transpiration is required to ensure that the limitation of having excess amounts of water is prevented. The mesophyll has two layers: an upper palisade layer and a lower spongy layer.
This is required so hydrophytes do not receive too much water. Petioles, stipules, veins, and a midrib are all essential structures of a leaf.
Leaf structure and function
It contains stomata, which are openings through which the exchange of gases takes place. It consists of the upper and lower epidermis, which are present on either side of the leaf. Learning Objectives Describe the internal structure and function of a leaf Key Takeaways Key Points The epidermis consists of the upper and lower epidermis; it aids in the regulation of gas exchange via stomata. The arrangement of leaves on a stem is known as phyllotaxy; leaves can be classified as either alternate, spiral, opposite, or whorled. Vein: The vein contains tubes called the xylem and phloem. It is where photosynthesis takes place. Leaf adaptations vary for different hydrophytes, due to the differences in their ecological niches. Botanists call the upper side the adaxial surface or adaxis and the lower side the abaxial surface or abaxis. In compound leaves, the lamina is separated into leaflets. A waxy cuticle covers all aerial surfaces of land plants to minimize water loss.
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