[8] Green plants are autotrophic, meaning that they do not obtain food from other living things but instead create their own food by photosynthesis. There is a regularity in these angles and they follow the numbers in a Fibonacci sequence: 1/2, 2/3, 3/5, 5/8, 8/13, 13/21, 21/34, 34/55, 55/89. A noble majestic tree presented itself as a sunset on a stick; covered with a thick dense fog of leaves. While playing around with word vectors and the "HasProperty" API of conceptnet, I had a bit of fun trying to get the adjectives which commonly describe a word. [2] Leaves are collectively referred to as foliage, as in "autumn foliage". The Role of Anthocyanins in Senescing Leaves of Red-Osier Dogwood", "Classification of the Architecture of Dicotyledonous Leaves", "The Bases of Angiosperm Phylogeny: Vegetative Morphology", "Influence of light availability on leaf structure and growth of two, "Shoot and compound leaf comparisons in eudicots: Dynamic morphology as an alternative approach", "The Role of Elastic Stresses on Leaf Venation Morphogenesis", "Venation patterns of neotropical blueberries (Vaccinieae: Ericaceae) and their phylogenetic utility", "Evolution and Function of Leaf Venation Architecture: A Review", "Leaf Vascular Systems in C3 and C4 Grasses: A Two-dimensional Analysis", "The Pea Key: An interactive key for Australian pea-flowered legumes", Institute of Food and Agricultural Sciences, International Code of Nomenclature for algae, fungi, and plants, International Code of Nomenclature for Cultivated Plants, International Association for Plant Taxonomy, https://en.wikipedia.org/w/index.php?title=Leaf&oldid=990323775, Short description is different from Wikidata, All Wikipedia articles written in American English, Wikipedia indefinitely move-protected pages, Articles with unsourced statements from April 2019, Pages using multiple image with manual scaled images, Pages using multiple image with auto scaled images, Wikipedia articles incorporating a citation from the 1911 Encyclopaedia Britannica with Wikisource reference, Creative Commons Attribution-ShareAlike License, Even; with a smooth margin; without toothing, Saw-toothed; with asymmetrical teeth pointing forward, With deep, wave-like indentations; coarsely crenate, Indented, with the indentations not reaching the center, Long-pointed, prolonged into a narrow, tapering point in a concave manner, Ending in a sharp, but not prolonged point, With a sharp, elongated, rigid tip; tipped with a cusp, Indented, with a shallow notch at the tip, Mucronate, but with a noticeably diminutive spine, All veins aligned mostly with the midvein, All veins branching repeatedly, net veined, Veins coming from the center of the leaf and radiating toward the edges, Tertiary veins running perpendicular to axis of main vein, connecting secondary veins, Other specialized leaves include those of, Alternate leaves have an angle of 180° (or ​. Leaf identification is helpful in classifying the variety of plant and its family. Monocots typically have such linear leaves that maximize surface area while minimising self-shading. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls and spines. Smothered with a dense collection of leaves. [11] Some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. Sometimes green, brown, yellow, yellow/red, or withered and crumbly Touch-some are smooth, some are rough and some have hairs on … In turn, smaller veins branch from the secondary veins, known as tertiary or third order (or higher order) veins, forming a dense reticulate pattern. However, the leaf may be dissected to form lobes, but the gaps between lobes do not reach to the main vein. The sheath is a structure, typically at the base that fully or partially clasps the stem above the node, where the latter is attached. Get answers by asking now. [26] Each subsequent branching is sequentially numbered, and these are the higher order veins, each branching being associated with a narrower vein diameter. Leaves provide trees with all their food because they turn sunlight into food energy. The characteristic features in an oak leaf are its lobes and sinuses (space between the lobes). It is covered with a waxy cuticle which is impermeable to liquid water and water vapor and forms the boundary separating the plant's inner cells from the external world. [42] Optical masking of chlorophyll by anthocyanins reduces risk of photo-oxidative damage to leaf cells as they senesce, which otherwise may lower the efficiency of nutrient retrieval from senescing autumn leaves. However, there are exceptions. Subpetiolate leaves are nearly petiolate or have an extremely short petiole and may appear to be sessile. [10] These are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. They are crucial to gathering energy, respiration and protection. Tear them and hear them rip, like thin cloth. In this regard, veins are called obscure and the order of veins that are obscured and whether upper, lower or both surfaces, further specified. The longest leaves are those of the Raffia palm, R. regalis which may be up to 25 m (82 ft) long and 3 m (9.8 ft) wide. [13], Leaves also function to store chemical energy and water (especially in succulents) and may become specialized organs serving other functions, such as tendrils of peas and other legumes, the protective spines of cacti and the insect traps in carnivorous plants such as Nepenthes and Sarracenia. In essence, leaves form a helix pattern centered around the stem, either clockwise or counterclockwise, with (depending upon the species) the same angle of divergence. For instance Pimenta racemosa has a channelled midrib on the upper surfae, but this is prominent on the lower surface. Leaves in temperate, boreal, and seasonally dry zones may be seasonally deciduous (falling off or dying for the inclement season). Carnelian can be used to describe leaves having a reddish-orange or brownish-red color, like the colors often found in the quartz by that name. [25] There are many elaborate variations on the patterns that the leaf veins form, and these have functional implications. True leaves or euphylls of larger size and with more complex venation did not become widespread in other groups until the Devonian period, by which time the carbon dioxide concentration in the atmosphere had dropped significantly. In peltate leaves, the petiole attaches to the blade inside the blade margin. In angiosperms the venation is typically parallel in monocotyledons and forms an interconnecting network in broad-leaved plants. Oak tree leaves may be deeply pinnatifid-like seen in Canada. There are different leaf types, exemplified by their form and shape as well as other characteristics. A pseudo-reticulate venation that is actually a highly modified penniparallel one is an autapomorphy of some Melanthiaceae, which are monocots; e.g., Paris quadrifolia (True-lover's Knot). beginners in secondary school). Simpson,[25] (and others)[55] divides parallel and netted (and some use only these two terms for Angiosperms)[56] on the basis of the number of primary veins (costa) as follows; These complex systems are not used much in morphological descriptions of taxa, but have usefulness in plant identification, Describing a tree in summer, spring, autumn and winter. The number of lobes may be from 5 up to 20 in a leaf. [41] Hydrostatic leaves such as in Prostanthera lasianthos are large and thin, and may involve the need for multiple leaves rather single large leaves because of the amount of veins needed to support the periphery of large leaves. A leaf (plural leaves) is the principal lateral appendage of the vascular plant stem,[1] usually borne above ground and specialized for photosynthesis. These primary and secondary veins are considered major veins or lower order veins, though some authors include third order. [27] In parallel veined leaves, the primary veins run parallel and equidistant to each other for most of the length of the leaf and then converge or fuse (anastomose) towards the apex. [52][25] At its simplest the primary vein types can be considered in three or four groups depending on the plant divisions being considered; where palmate refers to multiple primary veins that radiate from the petiole, as opposed to branching from the central main vein in the pinnate form, and encompasses both of Hickey types 4 and 5, which are preserved as subtypes; e.g., palmate-acrodromous (see National Park Service Leaf Guide).[53]. [41], Many leaves rely on hydrostatic support arranged around a skeleton of vascular tissue for their strength, which depends on maintaining leaf water status. [19] The terminology associated with the description of leaf morphology is presented, in illustrated form, at Wikibooks. [24][23][25], The vein or veins entering the leaf from the petiole are called primary or first-order veins. The leaves of bryophytes are only present on the gametophytes, while in contrast the leaves of vascular plants are only present on the sporophytes, and are associated with buds (immature shoot systems in the leaf axils). The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. [33] The epidermis serves several functions: protection against water loss by way of transpiration, regulation of gas exchange and secretion of metabolic compounds. [22] Thus, minor veins collect the products of photosynthesis (photosynthate) from the cells where it takes place, while major veins are responsible for its transport outside of the leaf. First, there is the blade. Deciduous plants in frigid or cold temperate regions typically shed their leaves in autumn, whereas in areas with a severe dry season, some plants may shed their leaves until the dry season ends. The colours in this photo are amazing – the leaves are gold, orange, yellow and brown. Leaves are normally extensively vascularized and typically have networks of vascular bundles containing xylem, which supplies water for photosynthesis, and phloem, which transports the sugars produced by photosynthesis. The flat, or laminar, shape also maximizes thermal contact with the surrounding air, promoting cooling. The proximal stalk or petiole is called a stipe in ferns. Because each leaflet can appear to be a simple leaf, it is important to recognize where the petiole occurs to identify a compound leaf. After the lesson, please also try my IELTS Interactive course. The leaves take in sunlight and use water and food from the roots to make the tree grow, and to reproduce. The word I'm looking for is something like "Leafing" or "Foliaging". Active 2 years, 7 months ago. [21][22] Within the lamina of the leaf, while some vascular plants possess only a single vein, in most this vasculature generally divides (ramifies) according to a variety of patterns (venation) and form cylindrical bundles, usually lying in the median plane of the mesophyll, between the two layers of epidermis. Golden leaves had begun their weakening, and gradually began to let go of their old lives for a new fading existence below on the surface world. Leaf sheathes typically occur in grasses and Apiaceae (umbellifers). In these a high proportion of longitudinal main veins provide additional support.[41]. Watch the leaves in the summer, when most of them had already acquired its final shape. These three tissue systems typically form a regular organization at the cellular scale. The leaves and stem together form the shoot. The lamina is typically the location of the majority of photosynthesis. The stem conducts water, minerals, and food to other parts of the plant and may also store food or be photosynthetic itself. Use words that describe the type of the tree it is (apple, oak, etc. [14] Leaves are the fundamental structural units from which cones are constructed in gymnosperms (each cone scale is a modified megaphyll leaf known as a sporophyll)[6]:408 and from which flowers are constructed in flowering plants. The light energy is trapped by the chlorophyll in the chloroplasts. Plants that lack chlorophyll cannot photosynthesize. (commonly called “umbrella plant”). The leaflets may have petiolules and stipels, the equivalents of the petioles and stipules of leaves. When the leaf is shed, it leaves a leaf scar on the twig. The phloem and xylem are parallel to each other, but the transport of materials is usually in opposite directions. Leaves are the most important organs of most vascular plants. 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