85-507: The Meikleour Beech Hedge(s) (European Beech = Fagus sylvatica ), located near Meikleour , Perth and Kinross , Scotland , was planted in the autumn of 1745 by Jean Mercer and her husband Robert Murray Nairne on the Marquess of Lansdowne 's Meikleour estate. It is said the hedge grows towards the heavens because the men who planted it were killed at the Battle of Culloden . The hedge lies alongside
170-422: A bud can produce a shoot with ten or more leaves. The terminal bud emits a hormonal substance in the spring that halts the development of additional buds. This tendency, though very strong at the beginning of their existence, becomes weaker in older trees. It is only after the budding that root growth of the year begins. The first roots to appear are very thin (with a diameter of less than 0.5 mm). Later, after
255-408: A decussate pattern, in which each node rotates by 1/4 (90°) as in the herb basil . The leaves of tricussate plants such as Nerium oleander form a triple helix. The leaves of some plants do not form helices. In some plants, the divergence angle changes as the plant grows. In orixate phyllotaxis, named after Orixa japonica , the divergence angle is not constant. Instead, it is periodic and follows
340-419: A few days). It is more precise in the north of its range than the south, and at 600 m (2,000 ft) than at sea level . The European beech invests significantly in summer and autumn for the following spring. Conditions in summer, particularly good rainfall, determine the number of leaves included in the buds. In autumn, the tree builds the reserves that will sustain it into spring. Given good conditions,
425-476: A heavy crop until the tree is at least 30 years old. F. sylvatica male flowers are borne in the small catkins which are a hallmark of the Fagales order (beeches, chestnuts, oaks, walnuts, hickories, birches, and hornbeams). The female flowers produce beechnuts, small triangular nuts 15–20 mm ( 5 ⁄ 8 – 3 ⁄ 4 in) long and 7–10 mm ( 1 ⁄ 4 – 3 ⁄ 8 in) wide at
510-789: A line from about north Suffolk across to Cardigan. Oak are the dominant forest trees north of this line. One of the most beautiful European beech forests called Sonian Forest ( Forêt de Soignes/Zoniënwoud ) is found in the southeast of Brussels, Belgium. Beech is a dominant tree species in France and constitutes about 10% of French forests. The largest virgin forests made of beech trees are Uholka-Shyrokyi Luh (8,800 hectares or 22,000 acres) in Ukraine and Izvoarele Nerei (5,012 ha or 12,380 acres in one forest body) in Semenic-Cheile Carașului National Park , Romania . These habitats are
595-504: A petiole like structure. Pseudopetioles occur in some monocotyledons including bananas , palms and bamboos . Stipules may be conspicuous (e.g. beans and roses ), soon falling or otherwise not obvious as in Moraceae or absent altogether as in the Magnoliaceae . A petiole may be absent (apetiolate), or the blade may not be laminar (flattened). The petiole mechanically links the leaf to
680-463: A plant matures; as a case in point Eucalyptus species commonly have isobilateral, pendent leaves when mature and dominating their neighbors; however, such trees tend to have erect or horizontal dorsiventral leaves as seedlings, when their growth is limited by the available light. Other factors include the need to balance water loss at high temperature and low humidity against the need to absorb atmospheric carbon dioxide. In most plants, leaves also are
765-468: A range of fungi including many Russula species, as well as Laccaria amethystina , and with the species Ramaria flavosaponaria . Tomentella Pat. species and Cenococcum geophilum have been found in Danish and Spanish beech forests. These fungi are important in enhancing uptake of water and nutrients from the soil. In the woodlands of southern Britain, beech is dominant over oak and elm south of
850-419: A regular organization at the cellular scale. Specialized cells that differ markedly from surrounding cells, and which often synthesize specialized products such as crystals, are termed idioblasts . The epidermis is the outer layer of cells covering the leaf. 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
935-475: A scaffolding matrix imparting mechanical rigidity to leaves. 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. Many leaves are covered in trichomes (small hairs) which have diverse structures and functions. The major tissue systems present are These three tissue systems typically form
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#17328477525651020-541: A severe dry season, some plants may shed their leaves until the dry season ends. In either case, the shed leaves may be expected to contribute their retained nutrients to the soil where they fall. In contrast, many other non-seasonal plants, such as palms and conifers, retain their leaves for long periods; Welwitschia retains its two main leaves throughout a lifetime that may exceed a thousand years. The leaf-like organs of bryophytes (e.g., mosses and liverworts ), known as phyllids , differ heavily morphologically from
1105-475: A short trunk with low branches. Fagus sylvatica is a large tree , capable of reaching heights of up to 50 metres (160 feet) tall and 3 m (10 ft) trunk diameter, though more typically 25–35 m (82–115 ft) tall and up to 1.5 m (5 ft) trunk diameter. A 10-year-old sapling will stand about 4 m (13 ft) tall. Undisturbed, the European beech has a lifespan of 300 years; one tree at
1190-402: A single (sometimes more) primary vein in the centre of the leaf, referred to as the midrib or costa, which is continuous with the vasculature of the petiole. The secondary veins, also known as second order veins or lateral veins, branch off from the midrib and extend toward the leaf margins. These often terminate in a hydathode , a secretory organ, at the margin. In turn, smaller veins branch from
1275-573: A single leaf grows from each node, and when the stem is held straight, the leaves form a helix . The divergence angle is often represented as a fraction of a full rotation around the stem. A rotation fraction of 1/2 (a divergence angle of 180°) produces an alternate arrangement, such as in Gasteria or the fan-aloe Kumara plicatilis . Rotation fractions of 1/3 (divergence angles of 120°) occur in beech and hazel . Oak and apricot rotate by 2/5, sunflowers, poplar, and pear by 3/8, and in willow and almond
1360-523: A single point. In evolutionary terms, early emerging taxa tend to have dichotomous branching with reticulate systems emerging later. Veins appeared in the Permian period (299–252 mya), prior to the appearance of angiosperms in the Triassic (252–201 mya), during which vein hierarchy appeared enabling higher function, larger leaf size and adaption to a wider variety of climatic conditions. Although it
1445-409: A small leaf. Stipules may be lasting and not be shed (a stipulate leaf, such as in roses and beans ), or be shed as the leaf expands, leaving a stipule scar on the twig (an exstipulate leaf). The situation, arrangement, and structure of the stipules is called the "stipulation". Veins (sometimes referred to as nerves) constitute one of the most visible features of leaves. The veins in a leaf represent
1530-410: A smoke flavouring, is produced from Fagus sylvatica. The wood of the European beech is used in the manufacture of numerous objects and implements. Its fine and short grain makes it an easy wood to work with, easy to soak, dye, varnish and glue. Steaming makes the wood even easier to machine. It has an excellent finish and is resistant to compression and splitting and it is stiff when flexed. Milling
1615-405: A specialized cell group known as the stomatal complex. The opening and closing of the stomatal aperture is controlled by the stomatal complex and regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Stomata therefore play the important role in allowing photosynthesis without letting the leaf dry out. In a typical leaf, the stomata are more numerous over
1700-483: A variety of patterns (venation) and form cylindrical bundles, usually lying in the median plane of the mesophyll , between the two layers of epidermis . This pattern is often specific to taxa, and of which angiosperms possess two main types, parallel and reticulate (net like). In general, parallel venation is typical of monocots, while reticulate is more typical of eudicots and magnoliids (" dicots "), though there are many exceptions. The vein or veins entering
1785-422: A wave of above ground growth, thicker roots grow in a steady fashion. Fagus sylvatica and other beeches are prone to false heartwood ('red heart') a condition where drought, nutrient deficient soil, branch breakage, pathogen infestation or other stressor induces formation of protection wood. False heartwood often manifests in the areas of the trunk associated with symplastless branches. As branch symplast dies,
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#17328477525651870-463: Is a stub . You can help Misplaced Pages by expanding it . This tree -related article is a stub . You can help Misplaced Pages by expanding it . European Beech Fagus orientalis (syn. F. sylvatica subsp. orientalis ) Fagus sylvatica , the European beech or common beech , is a large, graceful deciduous tree in the beech family with smooth silvery-gray bark, large leaf area, and
1955-522: Is an ascomycete primary pathogen of beech trees, causing strip-canker and wood rot. It can be found at all times of year and is not edible. European beech is a very popular ornamental tree in parks and large gardens in temperate regions of the world. In North America, they are preferred for this purpose over the native F. grandifolia , which despite its tolerance of warmer climates, is slower growing, taking an average of 10 years longer to attain maturity. The town of Brookline, Massachusetts has one of
2040-455: Is called a stipe in ferns . The lamina is the expanded, flat component of the leaf which contains the chloroplasts . The sheath is a structure, typically at the base that fully or partially clasps the stem above the node, where the leaf is attached. Leaf sheathes typically occur in Poaceae (grasses) and Apiaceae (umbellifers). Between the sheath and the lamina, there may be a pseudopetiole ,
2125-438: Is done by men working on a long ladder, from which they are able to reach with shears to about 60 feet. Local history says that this hedge was planted in 1745, and that the men who were planting it left their work to fight at the battle of Culloden, hiding their tools under the hedge, and never returning to claim them.[52] It is 580 yards long, and composed of tall, straight stems planted about 18 inches apart, and nearly touching at
2210-542: Is found more often on the side of a hill than at the bottom of clayey basin. It tolerates rigorous winter cold, but is sensitive to spring frost. In Norway's oceanic climate planted trees grow well north to Bodø Municipality , and produce seedlings and can spread naturally in Trondheim. In Sweden, beech trees do not grow as far north as in Norway. A beech forest is very dark and few species of plant are able to survive there, where
2295-461: Is not protected by a tar based on a distillate of its own bark (as used in railway sleepers ). It is better for paper pulp than many other broadleaved trees though is only sometimes used for this, the high cellulose content can also be spun into modal , which is used as a textile akin to cotton. The code for its use in Europe is fasy (from FA gus SY lvatica). Common beech is also considered one of
2380-405: Is one point at each vein tip, never any points between the veins. The buds are long and slender, 15–30 mm ( 5 ⁄ 8 – 1 + 1 ⁄ 8 in) long and 2–3 mm ( 3 ⁄ 32 – 1 ⁄ 8 in) thick, but thicker, up to 4–5 mm ( 1 ⁄ 8 – 1 ⁄ 4 in), where the buds include flower buds. The leaves of beech are often not abscissed (dropped) in
2465-462: Is sometimes difficult due to cracking. The density of the wood is 720 kilograms (1,590 pounds) per cubic metre. It is particularly well suited for minor carpentry, particularly furniture. From chairs to parquetry (flooring) and staircases, the European beech can do almost anything other than heavy structural support, so long as it is not left outdoors. Its hardness make it ideal for making wooden mallets and workbench tops. The wood rots easily if it
2550-442: Is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus , palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper ( adaxial ) and lower ( abaxial ) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases),
2635-406: Is the more complex pattern, branching veins appear to be plesiomorphic and in some form were present in ancient seed plants as long as 250 million years ago. 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). In leaves with reticulate venation, veins form
Meikleour Beech Hedges - Misplaced Pages Continue
2720-534: The A93 Perth - Blairgowrie Road, and can be viewed by visitors all year round. In 1906 Henry John Elwes and Augustine Henry , in the first volume of their Trees of Great Britain and Ireland , mention the "celebrated beech hedge of Meikleour" as one of the most striking effects produced by the beech in Scotland. "This hedge forms the boundary between the grounds and the highway, and has to be cut in periodically, which
2805-518: The Cantabrian , Iberian and Central mountain ranges), and east to northwest Turkey, where it exhibits an interspecific cline with the oriental beech ( Fagus orientalis ), which replaces it further east. In the Balkans, it shows some hybridisation with oriental beech; these hybrid trees are named Fagus × taurica Popl. [ Fagus moesiaca (Domin, Maly) Czecz.]. In the southern part of its range around
2890-544: The Royal Horticultural Society 's Award of Garden Merit :- The nuts are eaten by humans and animals. Slightly toxic to humans if eaten in large quantities due to the tannins and alkaloids they contain, the nuts were nonetheless pressed to obtain an oil in 19th-century England that was used for cooking and in lamps. They were also ground to make flour, which could be eaten after the tannins were leached out by soaking. Additionally, Primary Product AM 01 ,
2975-582: The Viking Age . However, the beech in Vestfold and at Seim north of Bergen in Norway is now spreading naturally and regarded as native . Though not demanding of its soil type, the European beech has several significant requirements: a humid atmosphere (precipitation well distributed throughout the year and frequent fogs) and well-drained soil (being intolerant of excessive stagnant water). It prefers moderately fertile ground, calcified or lightly acidic, therefore it
3060-494: The diet of many animals . Correspondingly, leaves represent heavy investment on the part of the plants bearing them, and their retention or disposition are the subject of elaborate strategies for dealing with pest pressures, seasonal conditions, and protective measures such as the growth of thorns and the production of phytoliths , lignins , tannins and poisons . Deciduous plants in frigid or cold temperate regions typically shed their leaves in autumn, whereas in areas with
3145-424: The gymnosperms and angiosperms . Euphylls are also referred to as macrophylls or megaphylls (large leaves). A structurally complete leaf of an angiosperm consists of a petiole (leaf stalk), a lamina (leaf blade), stipules (small structures located to either side of the base of the petiole) and a sheath. Not every species produces leaves with all of these structural components. The proximal stalk or petiole
3230-513: The nuts for food. The beech is classified as a native in the south of England and as a non-native in the north where it is often removed from 'native' woods. Localised pollen records have been recorded in the North of England from the Iron Age by Sir Harry Godwin . Changing climatic conditions may put beech populations in southern England under increased stress and while it may not be possible to maintain
3315-551: The phyllids of mosses and liverworts . Leaves are the most important organs of most vascular plants. Green plants are autotrophic , meaning that they do not obtain food from other living things but instead create their own food by photosynthesis . They capture the energy in sunlight and use it to make simple sugars , such as glucose and sucrose , from carbon dioxide and water. The sugars are then stored as starch , further processed by chemical synthesis into more complex organic molecules such as proteins or cellulose ,
3400-399: The plant shoots and roots . Vascular plants transport sucrose in a special tissue called the phloem . The phloem and xylem are parallel to each other, but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch (ramify) to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to
3485-587: The Mediterranean, and Sicily , it grows only in mountain forests, at 600–1,800 m (1,969–5,906 ft) altitude. Although often regarded as native in southern England, recent evidence suggests that F. sylvatica did not arrive in England until about 4000 BC, or 2,000 years subsequent to the English Channel forming following the ice ages; it could have been an early introduction by Stone Age humans, who used
Meikleour Beech Hedges - Misplaced Pages Continue
3570-478: The Valle Cervara site was more than 500 years old—the oldest known in the northern hemisphere. In cultivated forest stands trees are normally harvested at 80–120 years of age. 30 years are needed to attain full maturity (as compared to 40 for American beech ). Like most trees, its form depends on the location: in forest areas, F. sylvatica grows to over 30 m (100 ft), with branches being high up on
3655-490: The amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll which is essential for photosynthesis as it absorbs light energy from the sun . A leaf with lighter-colored or white patches or edges is called a variegated leaf . Leaves can have many different shapes, sizes, textures and colors. The broad, flat leaves with complex venation of flowering plants are known as megaphylls and
3740-679: The amount of light they absorb to avoid or mitigate excessive heat, ultraviolet damage, or desiccation, or to sacrifice light-absorption efficiency in favor of protection from herbivory. For xerophytes the major constraint is not light flux or intensity , but drought. Some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. and Bulbine mesembryanthemoides . 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,
3825-404: The autumn and instead remain on the tree until the spring. This process is called marcescence . This particularly occurs when trees are saplings or when plants are clipped as a hedge (making beech hedges attractive screens, even in winter), but it also often continues to occur on the lower branches when the tree is mature. Small quantities of seeds may be produced around 10 years of age, but not
3910-517: The base. The average height of the trees, as I am informed by Mr. Donald Matheson, is 95 feet, and their average girth at 3 feet is 18 to 36 inches. He adds that "close to the ground they are as fresh and green as a young hedge." An illustration of this hedge, taken specially for our work by Mr. D. Milne of Blairgowrie, gives a good idea of its appearance in October 1903." (The illustration is shown in Plate 11 of
3995-635: The base; there are two nuts in each cupule, maturing in the autumn 5–6 months after pollination. Flower and seed production is particularly abundant in years following a hot, sunny and dry summer, though rarely for two years in a row. The European beech is the most abundant hardwood species in Austrian, German and Swiss forests. The native range extends from the north, in Sweden , Denmark , Norway, Germany, Poland, Switzerland, Bulgaria, eastern parts of Russia, Romania, through Europe to France, southern England, Spain (on
4080-583: The basic structural material in plant cell walls, or metabolized by cellular respiration to provide chemical energy to run cellular processes. The leaves draw water from the ground in the transpiration stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through openings called stomata in the outer covering layer of the leaf ( epidermis ), while leaves are orientated to maximize their exposure to sunlight. Once sugar has been synthesized, it needs to be transported to areas of active growth such as
4165-424: The best firewoods for fireplaces. Crenate A leaf ( pl. : leaves ) is a principal appendage of the stem of a vascular plant , usually borne laterally above ground and specialized for photosynthesis . Leaves are collectively called foliage , as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue
4250-452: The blade attaches directly to the stem. Subpetiolate leaves are nearly petiolate or have an extremely short petiole and may appear to be sessile. In clasping or decurrent leaves, the blade partially surrounds the stem. When the leaf base completely surrounds the stem, the leaves are said to be perfoliate , such as in Eupatorium perfoliatum . In peltate leaves, the petiole attaches to
4335-406: The blade inside the blade margin. In some Acacia species, such as the koa tree ( Acacia koa ), the petioles are expanded or broadened and function like leaf blades; these are called phyllodes . There may or may not be normal pinnate leaves at the tip of the phyllode. A stipule , present on the leaves of many dicotyledons , is an appendage on each side at the base of the petiole, resembling
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#17328477525654420-515: The current levels of beech in some sites it is thought that conditions for beech in north-west England will remain favourable or even improve. It is often planted in Britain. Similarly, the nature of Norwegian beech populations is subject to debate. If native, they would represent the northern range of the species. However, molecular genetic analyses support the hypothesis that these populations represent intentional introduction from Denmark before and during
4505-595: The early Devonian lycopsid Baragwanathia , first evolved as enations, extensions of the stem. 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. This occurred independently in several separate lineages of vascular plants, in progymnosperms like Archaeopteris , in Sphenopsida , ferns and later in
4590-553: The equivalents of the petioles and stipules of leaves. Because each leaflet can appear to be a simple leaf, it is important to recognize where the petiole occurs to identify a compound leaf. Compound leaves are a characteristic of some families of higher plants, such as the Fabaceae . The middle vein of a compound leaf or a frond , when it is present, is called a rachis . Leaves which have a petiole (leaf stalk) are said to be petiolate . Sessile (epetiolate) leaves have no petiole and
4675-657: The external world. The cuticle is in some cases thinner on the lower epidermis than on the upper epidermis, and is generally thicker on leaves from dry climates as compared with those from wet climates. The epidermis serves several functions: protection against water loss by way of transpiration , regulation of gas exchange and secretion of metabolic compounds. Most leaves show dorsoventral anatomy: The upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. The epidermis tissue includes several differentiated cell types; epidermal cells, epidermal hair cells ( trichomes ), cells in
4760-406: The fraction is 5/13. These arrangements are periodic. The denominator of the rotation fraction indicates the number of leaves in one period, while the numerator indicates the number of complete turns or gyres made in one period. For example: Most divergence angles are related to the sequence of Fibonacci numbers F n . This sequence begins 1, 1, 2, 3, 5, 8, 13; each term is the sum of
4845-866: The ground, they are referred to as prostrate . Perennial plants whose leaves are shed annually are said to have deciduous leaves, while leaves that remain through winter are evergreens . Leaves attached to stems by stalks (known as petioles ) are called petiolate, and if attached directly to the stem with no petiole they are called sessile. Dicot leaves have blades with pinnate venation (where major veins diverge from one large mid-vein and have smaller connecting networks between them). Less commonly, dicot leaf blades may have palmate venation (several large veins diverging from petiole to leaf edges). Finally, some exhibit parallel venation. Monocot leaves in temperate climates usually have narrow blades, and usually parallel venation converging at leaf tips or edges. Some also have pinnate venation. The arrangement of leaves on
4930-526: The home of Europe's largest predators, (the brown bear, the grey wolf and the lynx). Many trees are older than 350 years in Izvoarele Nerei and even 500 years in Uholka-Shyrokyi Luh. Spring leaf budding by the European beech is triggered by a combination of day length and temperature. Bud break each year is from the middle of April to the beginning of May, often with remarkable precision (within
5015-566: The largest, if not the largest, grove of European beech trees in the United States. The 2.5-acre (1 ha) public park, called 'The Longwood Mall', was planted sometime before 1850 qualifying it as the oldest stand of European beeches in the United States. It is frequently kept clipped to make attractive hedges. Since the early 19th century there have been numerous cultivars of European beech made by horticultural selection, often repeatedly; they include: The following cultivars have gained
5100-443: The leaf from the petiole are called primary or first-order veins. The veins branching from these are secondary or second-order veins. These primary and secondary veins are considered major veins or lower order veins, though some authors include third order. Each subsequent branching is sequentially numbered, and these are the higher order veins, each branching being associated with a narrower vein diameter. In parallel veined leaves,
5185-523: The leaf veins form, and these have functional implications. Of these, angiosperms have the greatest diversity. Within these the major veins function as the support and distribution network for leaves and are correlated with leaf shape. For instance, the parallel venation found in most monocots correlates with their elongated leaf shape and wide leaf base, while reticulate venation is seen in simple entire leaves, while digitate leaves typically have venation in which three or more primary veins diverge radially from
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#17328477525655270-551: The leaves of vascular plants . In most cases, they lack vascular tissue, are only a single cell thick, and have no cuticle , stomata, or internal system of intercellular spaces. (The phyllids of the moss family Polytrichaceae are notable exceptions.) The phyllids of bryophytes are only present on the gametophytes , while in contrast the leaves of vascular plants are only present on the sporophytes . These can further develop into either vegetative or reproductive structures. Simple, vascularized leaves ( microphylls ), such as those of
5355-404: The photosynthetic organelles , the chloroplasts , to light and to increase the absorption of carbon dioxide while at the same time controlling water loss. Their surfaces are waterproofed by the plant cuticle and gas exchange between the mesophyll cells and the atmosphere is controlled by minute (length and width measured in tens of μm) openings called stomata which open or close to regulate
5440-412: The plant and provides the route for transfer of water and sugars to and from the leaf. The lamina is typically the location of the majority of photosynthesis. The upper ( adaxial ) angle between a leaf and a stem is known as the axil of the leaf. It is often the location of a bud . Structures located there are called "axillary". External leaf characteristics, such as shape, margin, hairs, the petiole, and
5525-434: The presence of stipules and glands, are frequently important for identifying plants to family, genus or species levels, and botanists have developed a rich terminology for describing leaf characteristics. Leaves almost always have determinate growth. They grow to a specific pattern and shape and then stop. Other plant parts like stems or roots have non-determinate growth, and will usually continue to grow as long as they have
5610-410: The previous two. Rotation fractions are often quotients F n / F n + 2 of a Fibonacci number by the number two terms later in the sequence. This is the case for the fractions 1/2, 1/3, 2/5, 3/8, and 5/13. The ratio between successive Fibonacci numbers tends to the golden ratio φ = (1 + √5)/2 . When a circle is divided into two arcs whose lengths are in the ratio 1:φ , the angle formed by
5695-465: The primary organs responsible for transpiration and guttation (beads of fluid forming at leaf margins). Leaves can also store food and water , and are modified accordingly to meet these functions, for example in the leaves of succulent plants and in bulb scales. The concentration of photosynthetic structures in leaves requires that they be richer in protein , minerals , and sugars than, say, woody stem tissues. Accordingly, leaves are prominent in
5780-429: 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. Usually, many smaller minor veins interconnect these primary veins, but may terminate with very fine vein endings in the mesophyll. Minor veins are more typical of angiosperms, which may have as many as four higher orders. In contrast, leaves with reticulate venation have
5865-416: The products of photosynthesis (photosynthate) from the cells where it takes place, while major veins are responsible for its transport outside of the leaf. At the same time water is being transported in the opposite direction. The number of vein endings is very variable, as is whether second order veins end at the margin, or link back to other veins. There are many elaborate variations on the patterns that
5950-429: The protective spines of cacti and the insect traps in carnivorous plants such as Nepenthes and Sarracenia . 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) and from which flowers are constructed in flowering plants . The internal organization of most kinds of leaves has evolved to maximize exposure of
6035-714: The rate exchange of carbon dioxide (CO 2 ), oxygen (O 2 ) and water vapor into and out of the internal intercellular space system. Stomatal opening is controlled by the turgor pressure in a pair of guard cells that surround the stomatal aperture. In any square centimeter of a plant leaf, there may be from 1,000 to 100,000 stomata. The shape and structure of leaves vary considerably from species to species of plant, depending largely on their adaptation to climate and available light, but also to other factors such as grazing animals (such as deer), available nutrients, and ecological competition from other plants. Considerable changes in leaf type occur within species, too, for example as
6120-531: The resources to do so. The type of leaf is usually characteristic of a species (monomorphic), although some species produce more than one type of leaf (dimorphic or polymorphic ). 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. The terminology associated with the description of leaf morphology is presented, in illustrated form, at Wikibooks . Where leaves are basal, and lie on
6205-446: The secondary veins, known as tertiary or third order (or higher order) veins, forming a dense reticulate pattern. The areas or islands of mesophyll lying between the higher order veins, are called areoles . Some of the smallest veins (veinlets) may have their endings in the areoles, a process known as areolation. These minor veins act as the sites of exchange between the mesophyll and the plant's vascular system. Thus, minor veins collect
6290-455: The sequence 180°, 90°, 180°, 270°. Two basic forms of leaves can be described considering the way the blade (lamina) is divided. A simple leaf has an undivided blade. However, the leaf may be dissected to form lobes, but the gaps between lobes do not reach to the main vein. A compound leaf has a fully subdivided blade, each leaflet of the blade being separated along a main or secondary vein. The leaflets may have petiolules and stipels,
6375-454: The smaller arc is the golden angle , which is 1/φ × 360° ≈ 137.5° . Because of this, many divergence angles are approximately 137.5° . In plants where a pair of opposite leaves grows from each node, the leaves form a double helix. If the nodes do not rotate (a rotation fraction of zero and a divergence angle of 0°), the two helices become a pair of parallel lines, creating a distichous arrangement as in maple or olive trees. More common in
6460-953: The species that bear them, the majority, as broad-leaved or megaphyllous plants, which also include acrogymnosperms and ferns . In the lycopods , with different evolutionary origins, the leaves are simple (with only a single vein) and are known as microphylls . Some leaves, such as bulb scales, are not above ground. In many aquatic species, the leaves are submerged in water. 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 . Furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes , and flattened leaf stems called phyllodes which differ from leaves both in their structure and origin. Some structures of non-vascular plants look and function much like leaves. Examples include
6545-421: The stem is known as phyllotaxis . A large variety of phyllotactic patterns occur in nature: In the simplest mathematical models of phyllotaxis , the apex of the stem is represented as a circle. Each new node is formed at the apex, and it is rotated by a constant angle from the previous node. This angle is called the divergence angle . The number of leaves that grow from a node depends on the plant species. When
6630-547: The stomatal complex; guard cells and subsidiary cells. The epidermal cells are the most numerous, largest, and least specialized and form the majority of the epidermis. They are typically more elongated in the leaves of monocots than in those of dicots . Chloroplasts are generally absent in epidermal cells, the exception being the guard cells of the stomata . The stomatal pores perforate the epidermis and are surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts, forming
6715-490: The sun barely reaches the ground. Young beeches prefer some shade and may grow poorly in full sunlight. In a clear-cut forest a European beech will germinate and then die of excessive dryness. Under oaks with sparse leaf cover it will quickly surpass them in height and, due to the beech's dense foliage, the oaks will die from lack of sunlight. The root system is shallow, even superficial, with large roots spreading out in all directions. European beech forms ectomycorrhizas with
6800-511: The surrounding air , promoting cooling. Functionally, in addition to carrying out photosynthesis, the leaf is the principal site of transpiration , providing the energy required to draw the transpiration stream up from the roots, and guttation . Many conifers have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and frost. These are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. Some leaf forms are adapted to modulate
6885-632: The transportation system. Typically leaves are broad, flat and thin (dorsiventrally flattened), thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts , thus promoting photosynthesis. They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance, plants adapted to windy conditions may have pendent leaves, such as in many willows and eucalypts . The flat, or laminar, shape also maximizes thermal contact with
6970-428: The trunk wood becomes depleted of nitrogen-containing molecules essential for life; this increases risk of catastrophic trunk failure. As the European beech exhibits deterministic leaf and shoot development and has a larger leaf area than other European hardwood trees, it is relatively more sensitive to drought and may respond to a dry summer with pre-senescent leafdrop . Biscogniauxia nummularia (beech tarcrust)
7055-407: The trunk. In open locations, it will become much shorter (typically 15–24 m or 50–80 ft) and more massive. The leaves are alternate, simple, and entire or with a slightly crenate margin, 5–10 cm (2– 3 + 7 ⁄ 8 in) long and 3–7 cm (1.2–2.8 in) broad, with 6–7 veins on each side of the leaf (as opposed to 7–10 veins in F. orientalis ). When crenate, there
7140-462: The vascular structure of the organ, extending into the leaf via the petiole and providing transportation of water and nutrients between leaf and stem, and play a crucial role in the maintenance of leaf water status and photosynthetic capacity. They also play a role in the mechanical support of the leaf. Within the lamina of the leaf, while some vascular plants possess only a single vein, in most this vasculature generally divides (ramifies) according to
7225-540: The volume). The hedge is noted in the Guinness World Records as the tallest and longest hedge on earth, reaching 30 metres (98 feet) in height and 530 metres (1,740 feet) in length. It is usually trimmed once every ten years, although the most recent trim, which took place in late 2019, was the first in almost 20 years. 56°32′01″N 3°21′51″W / 56.5335°N 3.3643°W / 56.5335; -3.3643 This Scotland -related article
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