palmately compound leaf
(noun)
leaf that has its leaflets radiating outwards from the end of the petiole
Examples of palmately compound leaf in the following topics:
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Types of Leaf Forms
- In a compound leaf, the leaf blade is completely divided, forming leaflets, as in the locust tree.
- A palmately compound leaf has its leaflets radiating outwards from the end of the petiole, like fingers off the palm of a hand.
- Examples of plants with palmately compound leaves include poison ivy, the buckeye tree, or the familiar house plant Schefflera sp.
- In a pinnately compound leaf, the middle vein is called the midrib.
- Compound leaves may be palmate or pinnate.
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Leaf Structure, Function, and Adaptation
- Leaves have many structures that prevent water loss, transport compounds, aid in gas exchange, and protect the plant as a whole.
- The outermost layer of the leaf is the epidermis.
- Trichomes help to avert herbivory by restricting insect movements or by storing toxic or bad-tasting compounds.
- Leaf trichomes include (b) branched trichomes on the leaf of Arabidopsis lyrata and (c) multibranched trichomes on a mature Quercus marilandica leaf.
- Stomata on the leaf underside allow gas exchange.
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The Chemical Basis for Life
- Carbon is the most important element to living things because it can form many different kinds of bonds and form essential compounds.
- Carbon exists in many forms in this leaf, including in the cellulose to form the leaf's structure and in chlorophyll, the pigment which makes the leaf green.
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Abscisic Acid, Ethylene, and Nontraditional Hormones
- Ethylene is associated with fruit ripening, flower wilting, and leaf fall.
- Horticulturalists inhibit leaf dropping in ornamental plants by removing ethylene from greenhouses using fans and ventilation.
- Recent research has discovered a number of compounds that also influence plant development.
- They contribute to the production of volatile compounds that attract natural enemies of predators.
- Signals between these compounds and other hormones, notably auxin and GAs, amplify their physiological effect.
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Plant Tissues and Organ Systems
- Intercalary meristems occur only in monocots at the bases of leaf blades and at nodes (the areas where leaves attach to a stem).
- This tissue enables the monocot leaf blade to increase in length from the leaf base; for example, it allows lawn grass leaves to elongate even after repeated mowing.
- Phloem tissue, which transports organic compounds from the site of photosynthesis to other parts of the plant, consists of four different cell types: sieve cells (which conduct photosynthates), companion cells, phloem parenchyma, and phloem fibers.
- Phloem cells, which transport sugars and other organic compounds from photosynthetic tissue to the rest of the plant, are living.
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Stem Anatomy
- They are found in the stem, the root, the inside of the leaf, and the pulp of the fruit.
- Both types have secondary cell walls that are thickened with deposits of lignin, an organic compound that is a key component of wood.
- The epidermis of a leaf also contains openings, known as stomata, through which the exchange of gases takes place .
- Two cells, known as guard cells, surround each leaf stoma, controlling its opening and closing and, thus, regulating the uptake of carbon dioxide and the release of oxygen and water vapor.
- They help to reduce transpiration (the loss of water by aboveground plant parts), increase solar reflectance, and store compounds that defend the leaves against predation by herbivores.
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Essential Nutrients for Plants
- The first of these macronutrients, carbon (C), is required to form carbohydrates, proteins, nucleic acids, and many other compounds; it is, therefore, present in all macromolecules.
- Hydrogen and oxygen are macronutrients that are part of many organic compounds and also form water.
- Symptoms of copper deficiency include browning of leaf tips and chlorosis (yellowing of the leaves).
- Inadequate magnesium also leads to (c) intervenal chlorosis, seen here in a sweetgum leaf.
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Mutualistic Relationships with Fungi and Fungivores
- Some cyanobacteria fix nitrogen from the atmosphere, contributing nitrogenous compounds to the association.
- In a second example, leaf-cutting ants of Central and South America literally farm fungi.
- They may be (a) crust-like, (b) hair-like, or (c) leaf-like.
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Mosses
- Such salts are a common ingredient of compounds marketed to eliminate mosses from lawns.
- The plants absorb water and nutrients directly through these leaf-like structures.
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Subphyla of Arthropoda
- Typically, the head bears one pair of sensory antennae, mandibles as mouthparts, a pair of compound eyes, and some ocelli (simple eyes), along with numerous sensory hairs.
- Myriapods are typically found in moist soils, decaying biological material, and leaf litter.