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A leaf (pl.: leaves) is a principal appendage of the stem of a vascular plant, [1] usually borne laterally above ground and specialized for photosynthesis.Leaves are collectively called foliage, as in "autumn foliage", [2] [3] while the leaves, stem, flower, and fruit collectively form the shoot system. [4]
The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients. The epidermis of most leaves shows dorsoventral anatomy : the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve ...
Water beads on the waxy cuticle of kale leaves. A plant cuticle is a protecting film covering the outermost skin layer of leaves, young shoots and other aerial plant organs (aerial here meaning all plant parts not embedded in soil or other substrate) that have no periderm. The film consists of lipid and hydrocarbon polymers infused with wax ...
Bulb: A short vertical underground stem with fleshy storage leaves attached, e.g. onion, daffodil, and tulip. Bulbs often function in reproduction by splitting to form new bulbs or producing small new bulbs termed bulblets. Bulbs are a combination of stem and leaves so may better be considered as leaves because the leaves make up the greater part.
The functions of the stem are to raise and support the leaves and reproductive organs above the level of the soil, to facilitate absorption of light for photosynthesis, gas exchange, water exchange (transpiration), pollination, and seed dispersal. The stem also serves as a conduit, from roots to overhead structures, for water and other growth ...
Parenchyma cells have a variety of functions: In leaves, they form two layers of mesophyll cells immediately beneath the epidermis of the leaf, that are responsible for photosynthesis and the exchange of gases. [2] These layers are called the palisade parenchyma and spongy mesophyll. Palisade parenchyma cells can be either cuboidal or elongated.
Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem Detail of the vasculature of a bramble leaf Translocation in vascular plants. Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem ...
Leaf of Pyrus calleryana with petiole. In botany, the petiole (/ ˈ p iː t i. oʊ l /) is the stalk that attaches the leaf blade to the stem. [1]: 87 [2]: 171 It is able to twist the leaf to face the sun, producing a characteristic foliage arrangement (spacing of blades), and also optimizing its exposure to sunlight.