77-476: Guanacaste can refer to: Guanacaste, the common tropical American tree Enterolobium cyclocarpum Places [ edit ] Belize [ edit ] Guanacaste National Park (Belize) , a small national park in Belize Costa Rica [ edit ] Guanacaste Province , a province of Costa Rica Guanacaste National Park (Costa Rica) ,
154-438: A 2–6 cm (0.79–2.36 in) petiole bearing four to 15 pairs of pinnae, each pinna with 40–70 leaflets; the leaflets are slender, oblong, 8–15 mm (0.315–0.591 in) long by 2–4 mm (0.079–0.157 in) wide. Near its base, the twiggy petiole bares a small, raised, oval gland. The leaves are confined to the outer shell of the crown, yet they are plentiful enough to make it moderately dense and green. The guanacaste
231-516: A conspicuous light brown or orange ring. They are very hard, resembling small stones rather than tree seeds in their strength and durability. For germination to occur, the hard seed coat must be broken to enable water to reach the embryo. Otherwise, the seeds lie dormant indefinitely. The ardillo ( Cojoba arborea ) and the iguano ( Dilodendron costaricense ) possess similar bipinnate leaves with extra-fine leaflets. Though of equally impressive stature, these two trees can be distinguished readily from
308-408: 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
385-515: 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
462-463: 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
539-419: 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
616-475: 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
693-541: 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
770-402: 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
847-578: 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
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#1732772403289924-466: A single pistil, bound together at the base by a short, green, tubular corolla and an even shorter calyx, just 5 mm (0.197 in) long altogether. Guanacaste flowers are very fragrant, and during intense flowering periods, their odor permeates the air for many meters in all directions. In Manuel Antonio National Park near Quepos, Costa Rica, flowering lasts from late February to early April. Surprisingly, no obvious fruiting activity immediately follows
1001-533: 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
1078-409: 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
1155-729: A small national park in Costa Rica Guanacaste Cordillera a mountain range in Costa Rica Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Guanacaste . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Guanacaste&oldid=819822225 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description
1232-405: 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
1309-483: 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
1386-697: Is evergreen , or briefly deciduous for 1–2 months during the dry season . Most foliage is shed in December, at the start of the dry season. In late February, a growth surge is initiated that re-establishes a fresh, thick crown by April. Concurrent with the leaves' renewal is the appearance of globular inflorescences (3 cm (1.18 in)) in the axils of the new leaves. Supported by a long pedestal (4 cm (1.57 in)), each spherical white head – composed of about 50 individual flowers – sports thousands of thin, filamentous stamens as its major feature. The blossoms themselves each consist of about 20 stamens and
1463-404: Is a medium-sized to large tree , growing to 25–35 m (82–115 ft) tall, with a trunk up to 3.5 m (11 ft) in diameter. Unusual in a tree of these proportions, buttresses are completely lacking. The bark is light gray, with prominent dark reddish-brown, vertical fissures. In young trees, these fissures are closer together. and their confluence lends a characteristic reddish hue to
1540-460: 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 ,
1617-409: Is different from Wikidata All article disambiguation pages All disambiguation pages Enterolobium cyclocarpum Several, see text Enterolobium cyclocarpum , commonly known as conacaste , guanacaste , caro caro , devil's ear tree , monkey-ear tree , or elephant-ear tree , is a species of flowering tree in the family Fabaceae , that is native to tropical regions of
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#17327724032891694-534: Is the national tree of Costa Rica. In North America, it is often called elephant-ear tree, due to the shape of the seedpods. Other common names include devil's ear and earpod tree, parota , and orejón (Spanish) or' huanacaxtle ( Nahuatl ). In El Salvador , it is known as conacaste . In the Yucatán peninsula, it is known by the Mayan name, pich. In Panama, it is known as a corotú . Source: The guanacaste
1771-406: 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
1848-530: Is used to make items such as doors, windows, furniture, and cabinets, and for shipbuilding. It is considered a relatively sustainable resource for wooden furniture and design projects, largely due to the tree's ability to quickly reach large sizes, which also makes it easier to find large natural cuts up to several meters, which is rare for other slower-growing woods, such as oak or cedar. The town of La Cruz de Huanacaxtle in Nayarit (Mexico) derives its name from
1925-692: The Costa Rican Central Valley , produces spherical green galls of 1.5 cm (0.59 in) diameter on new shoots in February and March. Similar parasitism seems to occur on guanacaste trees of the wet, southwestern lowlands (around Palmar Sur ). The guanacaste is among the most majestic and aesthetically pleasing of tree species in its native range. Tolerant of a wide range of rainfall levels, temperatures, and soil conditions, they can thrive in most low-elevation, tropical habitats. Guanacaste trees are highly valued as ornamentals, and
2002-494: 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
2079-424: 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
2156-551: 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 ,
2233-399: 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
2310-438: 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 is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including
2387-542: The Americas, from central Mexico south to northern Brazil ( Roraima ) and Venezuela. It is known for its large proportions, expansive, often spherical crown, and curiously shaped seedpods. The abundance of this tree, especially in Guanacaste Province , Costa Rica , where it is prized for the shady relief it provides from the intense sun, coupled with its immensity, have made it a widely recognized species. It
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2464-679: 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,
2541-421: The astringent properties of its green fruit are used for diarrhea. The fruit and bark also contain tannins, which are useful for leather curing and soap manufacturing, while the sap can be used as a natural adhesive or substitute for glue, or chewed as a type of gum. The guanacaste has in the past been referred to by these junior synonyms : Leaf A leaf ( pl. : leaves ) is a principal appendage of
2618-461: The bark of guanacaste saplings. Older specimens often present broken, chipped, or scarred bark. The crown is broad and widely spreading. The height at which branches first occur along the trunk – as well as the overall tree shape – vary considerably among individuals and are habitat-dependent characteristics. Frequently, guanacaste trees grow as single specimens in a sunny pasture. Under these conditions, massive, extended, horizontal limbs emerge low on
2695-583: 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
2772-458: 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
2849-406: 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
2926-474: The boles, forming giant, hemispherical, widely spreading crowns. In the forest (where competition for light is intense), trees tend to become taller, and branching occurs at a higher level. Tree forms then become somewhat narrower, though crowns are still rounded, and hemispherical shapes are maintained by those that have reached the canopy. The alternate leaves are bipinnate compound, 15–40 cm (5.91–15.75 in) long and 17 cm (6.69 in) broad with
3003-527: The decline of the blossom. Rather, 9–10 months pass before small, green pods first appear high in the crown by December. They reach full size by February and finally begin to ripen in March – a full year after flowering has ceased. Fruit ripening lasts from March to April, as the green pods turn brown in the guanacaste crown and are slowly shed. Vigorous trees produce large crops on a nearly annual basis. In June, guanacaste seedlings can already be seen, germinating in
3080-606: 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
3157-558: 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
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3234-657: 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
3311-789: The fact that a cross used to stand there made of guanacaste wood. While the seed pods are still green, they are harvested and the seeds eaten boiled in Mexico. Healthy guanacaste trees generate massive, nearly annual crops of seeds. The attractive seeds are used in Costa Rica to make jewelry. In parts of Panama, the ripe seeds are heated in a fire until they pop like popcorn. These seeds demonstrate germination rates of nearly 100%. Guanacaste seedlings then grow rapidly, often reaching over 1 m (3 ft 3 in) in height in their first year. These aggressive reproductive characteristics might be beneficially exploited in reforestation projects, though
3388-406: 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
3465-866: 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
3542-409: The guanacaste; the ardillo has tan-colored, heavily wrinkled, and rough bark – nothing like the guanacaste's unmistakably gray and vertically cracked cortex. The iguano's leaflets are serrated (an unusual feature in a bipinnate tree), while those of the guanacaste are entire. Guanacaste trees appear to delay the onset of fruit development—some 9 months—so that seed maturation coincides with the start of
3619-443: 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,
3696-523: 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
3773-551: 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
3850-925: 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
3927-421: 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), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to
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#17327724032894004-662: The moist soil of the early rainy season. Guanacaste fruits are large (7–12 cm (2.8–4.7 in) diameter), glossy dark brown indehiscent and spirally organized pods, shaped like orbicular disks. Their shape suggests the usual Mimosoideae fruit – a long, narrow, flattened pod – taken and wound around an axis perpendicular to its plane. Made of thick, soft tissue with a leathery feel, the pods contain eight to 20 radially arranged seeds, 14.5–17.5 mm (0.571–0.689 in) long, 7.8–11.2 mm (0.307–0.441 in) wide, and 6.2–7.2 mm (0.244–0.283 in) thick and weighing about 1 g. Guanacaste seeds are brown and marked with
4081-404: 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
4158-533: The plant an evolutionary anachronism : it has been suggested that guanacaste pods were among the foods exploited by certain species of Pleistocene megafauna that became extinct some 10,000 years ago (e.g. giant ground sloths , giant bison ). Within this scenario, the tree remains today without an effective seed-dispersing vector besides humans. As discussed above, the tough-coated guanacaste seeds do not begin to grow unless their protective covers are punctured in some way. This may be an adaptation designed to keep
4235-412: 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
4312-449: The plant is considered an invasive species in some places. Its roots are strong, and those of large trees may damage nearby structures. Guanacaste is commonly used to feed all kind of livestock; its foliage, fruits, and seeds are relished by cattle, pigs, goats, sheep, and horses. The parota tree is believed to provide medical benefits. In Mexican folk medicine, the sap is thought to aid illnesses such as influenza and bronchitis, while
4389-411: 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 the species that bear them,
4466-434: 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
4543-410: 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
4620-465: 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
4697-429: 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
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#17327724032894774-416: 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
4851-429: 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
4928-402: The rainy season. This adaptive behavior presumably is an adaptation to give germinating seedlings as much time as possible to establish root systems before the start of the next dry season. Both the jatobá ( Hymenaea courbaril ) and the cenizaro ( Albizia saman ) exhibit similar reproductive strategies. Of course, guanacaste trees—like all deciduous and semideciduous species in this part of
5005-714: 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
5082-535: 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
5159-446: 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
5236-583: The seeds from germinating while still in the pods at the start of the rainy season —and very likely still underneath the parent tree after having fallen from its crown. With more time to find them, foraging ground sloths (and other extinct mammals) could eat the pods and transport the seeds to a new site. The resulting mastication and digestion of the fruits would induce seed coat abrasion, which would help seed germination. Nowadays this role of mastication and dispersal has been taken up primarily by horses and cattle . An insect pest , common to guanacaste trees of
5313-455: 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,
5390-526: The shade they provide creates many an oasis on the searing and sun-baked plains in its Pacific slope habitat. It is widely grown as a shade tree to shelter coffee plantations and for shade and forage for cattle; it also improves soil fertility by nitrogen fixation . The guanacaste is found in USDA Growth Zones 10–12. The wood is reddish-brown, lightweight (density 0.34–0.6 g/cm (0.20–0.35 oz/cu in)) and water-resistant; it
5467-454: 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
5544-421: 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
5621-547: 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
5698-511: 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
5775-632: 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
5852-462: 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
5929-420: The world—share in the water-conserving benefits of dry-season leaflessness. Guanacaste flowers are heavily visited by bees —insects that probably are responsible for pollination, as well. Guanacaste seed pods, however, are completely ignored by native fauna and they accumulate on the forest floor underneath parent trees. The seeds are not eaten by any animals currently native where the tree occurs, rendering
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