The hazel is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is placed in the birch family Betulaceae, though some botanists split the hazels into a separate family Corylaceae; the fruit of the hazel is the hazelnut. Hazels have rounded leaves with double-serrate margins; the flowers are produced early in spring before the leaves, are monoecious, with single-sex catkins, the male catkins are pale yellow and 5–12 cm long, the female ones are small and concealed in the buds, with only the bright-red, 1-to-3 mm-long styles visible. The fruits are nuts 1–2.5 cm long and 1–2 cm diameter, surrounded by an involucre which to encloses the nut. The shape and structure of the involucre, the growth habit, are important in the identification of the different species of hazel; the pollen of hazel species, which are the cause for allergies in late winter or early spring, can be identified under magnification by their characteristic granular exines bearing three conspicuous pores.
Corylus has 14–18 species. The circumscription of species in eastern Asia is disputed, with WCSP and the Flora of China differing in which taxa are accepted; the species are grouped as follows: Nut surrounded by a soft, leafy involucre, multiple-stemmed, suckering shrubs to 12 m tall Involucre short, about the same length as the nut Corylus americana—American hazel, eastern North America Corylus avellana—Common hazel and western Asia Corylus heterophylla—Asian hazel, Asia Corylus yunnanensis—Yunnan hazel and southern China Involucre long, twice the length of the nut or more, forming a'beak' Corylus colchica—Colchican filbert, Caucasus Corylus cornuta—Beaked hazel, North America Corylus maxima—Filbert, southeastern Europe and southwest Asia Corylus sieboldiana—Asian beaked hazel, northeastern Asia and Japan Nut surrounded by a stiff, spiny involucre, single-stemmed trees to 20–35 m tall Involucre moderately spiny and with glandular hairs Corylus chinensis—Chinese hazel, western China Corylus colurna—Turkish hazel, southeastern Europe and Asia Minor Corylus fargesii—Farges' hazel, western China Corylus jacquemontii—Jacquemont's hazel, Himalaya Corylus wangii—Wang's hazel, southwest China Involucre densely spiny, resembling a chestnut burr Corylus ferox—Himalayan hazel, Himalaya and southwest China.
Several hybrids exist, can occur between species in different sections of the genus, e.g. Corylus × colurnoides; the oldest confirmed hazel species is Corylus johnsonii found as fossils in the Ypresian-age rocks of Ferry County, Washington. The nuts of all hazels are edible; the common hazel is the species most extensively grown for its nuts, followed in importance by the filbert. Nuts are harvested from the other species, but apart from the filbert, none is of significant commercial importance. A number of cultivars of the common hazel and filbert are grown as ornamental plants in gardens, including forms with contorted stems. Hazel is a traditional material used for making wattle, withy fencing and the frames of coracle boats; the tree can be coppiced, regenerating shoots allow for harvests every few years. Hazels are used as food plants by the larvae of various species of Lepidoptera; the Celts believed hazelnuts gave one inspiration. There are numerous variations on an ancient tale that nine hazel trees grew around a sacred pool, dropping into the water nuts that were eaten by salmon, which absorbed the wisdom.
A Druid teacher, in his bid to become omniscient, caught one of these special salmon and asked a student to cook the fish, but not to eat it. While he was cooking it, a blister formed and the pupil used his thumb to burst it, which he sucked to cool, thereby absorbing the fish's wisdom; this boy was called Fionn Mac Cumhail and went on to become one of the most heroic leaders in Gaelic mythology."The Hazel Branch" from Grimms' Fairy Tales claims that hazel branches offer the greatest protection from snakes and other things that creep on the earth. Eichhorn, Markus. "The Hazel Tree". Test Tube. Brady Haran for the University of Nottingham
Plants are multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. Plants were treated as one of two kingdoms including all living things that were not animals, all algae and fungi were treated as plants. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes. By one definition, plants form the clade Viridiplantae, a group that includes the flowering plants and other gymnosperms and their allies, liverworts and the green algae, but excludes the red and brown algae. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria, their chloroplasts contain b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is common.
There are about 320 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants. Green plants provide a substantial proportion of the world's molecular oxygen and are the basis of most of Earth's ecosystems on land. Plants that produce grain and vegetables form humankind's basic foods, have been domesticated for millennia. Plants have many cultural and other uses, as ornaments, building materials, writing material and, in great variety, they have been the source of medicines and psychoactive drugs; the scientific study of plants is known as a branch of biology. All living things were traditionally placed into one of two groups and animals; this classification may date from Aristotle, who made the distincton between plants, which do not move, animals, which are mobile to catch their food. Much when Linnaeus created the basis of the modern system of scientific classification, these two groups became the kingdoms Vegetabilia and Animalia. Since it has become clear that the plant kingdom as defined included several unrelated groups, the fungi and several groups of algae were removed to new kingdoms.
However, these organisms are still considered plants in popular contexts. The term "plant" implies the possession of the following traits multicellularity, possession of cell walls containing cellulose and the ability to carry out photosynthesis with primary chloroplasts; when the name Plantae or plant is applied to a specific group of organisms or taxon, it refers to one of four concepts. From least to most inclusive, these four groupings are: Another way of looking at the relationships between the different groups that have been called "plants" is through a cladogram, which shows their evolutionary relationships; these are not yet settled, but one accepted relationship between the three groups described above is shown below. Those which have been called "plants" are in bold; the way in which the groups of green algae are combined and named varies between authors. Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom.
The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the green algae, red algae and brown algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, they are no longer classified as plants as defined here; the Viridiplantae, the green plants – green algae and land plants – form a clade, a group consisting of all the descendants of a common ancestor. With a few exceptions, the green plants have the following features in common, they undergo closed mitosis without centrioles, have mitochondria with flat cristae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. Two additional groups, the Rhodophyta and Glaucophyta have primary chloroplasts that appear to be derived directly from endosymbiotic cyanobacteria, although they differ from Viridiplantae in the pigments which are used in photosynthesis and so are different in colour.
These groups differ from green plants in that the storage polysaccharide is floridean starch and is stored in the cytoplasm rather than in the plastids. They appear to have had a common origin with Viridiplantae and the three groups form the clade Archaeplastida, whose name implies that their chloroplasts were derived from a single ancient endosymbiotic event; this is the broadest modern definition of the term'plant'. In contrast, most other algae not only have different pigments but have chloroplasts with three or four surrounding membranes, they are not close relatives of the Archaeplastida having acquired chloroplasts separately from ingested or symbiotic green and red algae. They are thus not included in the broadest modern definition of the plant kingdom, although they were in the past; the green plants or Viridiplantae were traditionally divided into the green algae (including
In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. Trees tend to be long-lived, some reaching several thousand years old. In wider definitions, the taller palms, tree ferns and bamboos are trees. Trees have been in existence for 370 million years, it is estimated. A tree has many secondary branches supported clear of the ground by the trunk; this trunk contains woody tissue for strength, vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark. Below the ground, the roots spread out widely. Above ground, the branches divide into smaller shoots.
The shoots bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Trees reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms and bamboos produce seeds, but tree ferns produce spores instead. Trees play a significant role in moderating the climate, they remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture; because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, they play a role in many of the world's mythologies.
Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are typically defined by height, with smaller plants from 0.5 to 10 m being called shrubs, so the minimum height of a tree is only loosely defined. Large herbaceous plants such as papaya and bananas are trees in this broad sense. A applied narrower definition is that a tree has a woody trunk formed by secondary growth, meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the growing tip. Under such a definition, herbaceous plants such as palms and papayas are not considered trees regardless of their height, growth form or stem girth. Certain monocots may be considered trees under a looser definition.
Aside from structural definitions, trees are defined by use. The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight. Trees tend some reaching several thousand years old. Several trees are among the oldest organisms now living. Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage, they differ from shrubs, which have a similar growth form, by growing larger and having a single main stem. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species; the greatest number of these grow in tropical regions and many of these areas have not yet been surveyed by botanists, making tree diversity and ranges poorly known.
The majority of tree species are angiosperms. There are about 1000 species of gymnosperm trees, including conifers, cycads and gnetales. Most angiosperm trees are eudicots, the "true dicotyledons", so named because the seeds contain two cotyledons or seed leaves. There are some trees among the old lineages of flowering plants called basal angiosperms or paleodicots. Wood gives structural strength to the trunk of most types of tree; the vascular system of trees allows water and other chemicals to be di
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar and cottonwood. In the September 2006 issue of Science Magazine, the Joint Genome Institute announced that the western balsam poplar was the first tree whose full DNA code had been determined by DNA sequencing; the genus has a large genetic diversity, can grow from 15–50 m tall, with trunks up to 2.5 m in diameter. The bark on young trees is smooth, white to greenish or dark grey, has conspicuous lenticels; the shoots are stout, with the terminal bud present. The leaves are spirally arranged, vary in shape from triangular to circular or lobed, with a long petiole. Leaf size is variable on a single tree with small leaves on side shoots, large leaves on strong-growing lead shoots; the leaves turn bright gold to yellow before they fall during autumn. The flowers are dioecious and appear in early spring before the leaves.
They are borne in long, sessile or pedunculate catkins produced from buds formed in the axils of the leaves of the previous year. The flowers are each seated in a cup-shaped disk, borne on the base of a scale, itself attached to the rachis of the catkin; the scales are obovate and fringed, hairy or smooth, caducous. The male flowers are without calyx or corolla, comprise a group of four to 60 stamens inserted on a disk; the female flower has no calyx or corolla, comprises a single-celled ovary seated in a cup-shaped disk. The style is short, with two to four stigmata, variously lobed, numerous ovules. Pollination is by wind, with the female catkins lengthening between pollination and maturity; the fruit is a two- to four-valved dehiscent capsule, green to reddish-brown, mature in midsummer, containing numerous minute light brown seeds surrounded by tufts of long, white hairs which aid wind dispersal. Poplars of the cottonwood section are wetlands or riparian trees; the aspens are among the most important boreal broadleaf trees.
Poplars and aspens are important food plants for the larvae of a large number of Lepidoptera species. Pleurotus populinus, the aspen oyster mushroom, is found on dead wood of Populus trees in North America. Several species of Populus in the United Kingdom and other parts of Europe have experienced heavy dieback; the genus Populus has traditionally been divided into six sections on the basis of leaf and flower characters. Recent genetic studies have supported this, confirming some suspected reticulate evolution due to past hybridisation and introgression events between the groups; some species had differing relationships indicated by their nuclear DNA and chloroplast DNA sequences, a clear indication of hybrid origin. Hybridisation continues to be common in the genus, with several hybrids between species in different sections known. Populus section Populus – aspens and white poplar Populus adenopoda – Chinese aspen Populus alba – white poplar Populus × canescens – grey poplar Populus spp. X – Pacific albus Populus davidiana – Korean aspen Populus grandidentata – bigtooth aspen Populus sieboldii – Japanese aspen Populus tremula – aspen, common aspen, Eurasian aspen, European aspen, quaking aspen Populus tremuloides – quaking aspen or trembling aspen Populus section Aigeiros – black poplars, some of the cottonwoods Populus deltoides – eastern cottonwood Populus fremontii – Fremont cottonwood Populus nigra – black poplar, placed here by nuclear DNA.
Populus Populus × canadensis – hybrid black poplar Populus × inopina – hybrid black poplar Populus section Tacamahaca – balsam poplars Populus angustifolia – willow-leaved poplar or narrowleaf cottonwood Populus balsamifera – Balsam poplar Populus cathayana – Populus koreana J. Rehnder – Korean poplar Populus laurifolia – laurel-leaf poplar Populus maximowiczii A. Henry – Maximowicz' poplar, Japanese poplar Populus simonii – Simon's poplar Populus suaveolens Fischer – Mongolian poplar Populus szechuanica – Sichuan poplar, placed here by nuclear DNA. Aigeiros Populus trichocarpa – western balsam poplar or black cottonwood Populus tristis, placed here by nuclear DNA.
Petals are modified leaves that surround the reproductive parts of flowers. They are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are accompanied by another set of special leaves called sepals, that collectively form the calyx and lie just beneath the corolla; the calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished petals; when the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots. Although petals are the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, either have small petals or lack them entirely.
The role of the corolla in plant evolution has been studied extensively since Charles Darwin postulated a theory of the origin of elongated corollae and corolla tubes. A corolla of separate tepals is apopetalous. If the petals are free from one another in the corolla, the plant is choripetalous. In the case of fused tepals, the term is syntepalous; the corolla in some plants forms a tube. Petals can differ in different species; the number of petals in a flower may hold clues to a plant's classification. For example, flowers on eudicots most have four or five petals while flowers on monocots have three or six petals, although there are many exceptions to this rule; the petal whorl or corolla may be bilaterally symmetrical. If all of the petals are identical in size and shape, the flower is said to be regular or actinomorphic. Many flowers are termed irregular or zygomorphic. In irregular flowers, other floral parts may be modified from the regular form, but the petals show the greatest deviation from radial symmetry.
Examples of zygomorphic flowers may be seen in members of the pea family. In many plants of the aster family such as the sunflower, Helianthus annuus, the circumference of the flower head is composed of ray florets; each ray floret is anatomically an individual flower with a single large petal. Florets in the centre of the disc have no or reduced petals. In some plants such as Narcissus the lower part of the petals or tepals are fused to form a floral cup above the ovary, from which the petals proper extend. Petal consists of two parts: the upper, broad part, similar to leaf blade called the blade and the lower part, similar to leaf petiole, called the claw, separated from each other at the limb. Claws are developed in petals of some flowers such as Erysimum cheiri; the inception and further development of petals shows a great variety of patterns. Petals of different species of plants vary in colour or colour pattern, both in visible light and in ultraviolet; such patterns function as guides to pollinators, are variously known as nectar guides, pollen guides, floral guides.
The genetics behind the formation of petals, in accordance with the ABC model of flower development, are that sepals, petals and carpels are modified versions of each other. It appears that the mechanisms to form petals evolved few times, rather than evolving from stamens. Pollination is an important step in the sexual reproduction of higher plants. Pollen is produced by the male organs of hermaphroditic flowers. Pollen does not move on its own and thus requires wind or animal pollinators to disperse the pollen to the stigma of the same or nearby flowers. However, pollinators are rather selective in determining the flowers; this develops competition between flowers and as a result flowers must provide incentives to appeal to pollinators. Petals play a major role in competing to attract pollinators. Henceforth pollination dispersal could occur and the survival of many species of flowers could prolong. Petals have various purposes depending on the type of plant. In general, petals operate to protect some parts of the flower and attract/repel specific pollinators.
This is where the positioning of the flower petals are located on the flower is the corolla e.g. the buttercup having shiny yellow flower petals which contain guidelines amongst the petals in aiding the pollinator towards the nectar. Pollinators have the ability to determine specific flowers. Using incentives flowers draw pollinators and set up a mutual relation between each other in which case the pollinators will remember to always guard and pollinate these flowers; the petals could produce different scents to allure desirable pollinators or repel undesirable pollinators. Some flowers will mimic the scents produced by materials such as decaying meat, to attract pollinators to them. Various colour traits are used by different petals that could attract pollinators that have poor smelling abilities, or that only come out at certain parts of the day; some flowers are able to change the colour
Morus, a genus of flowering plants in the family Moraceae, comprises 10–16 species of deciduous trees known as mulberries, growing wild and under cultivation in many temperate world regions. The related genus Broussonetia is commonly known as mulberry, notably the paper mulberry, Broussonetia papyrifera. Mulberries are fast-growing when young, but soon become slow-growing and exceed 10–15 metres tall; the leaves are alternately arranged and lobed and serrated on the margin. Lobes are more common on juvenile shoots than on mature trees; the trees can be dioecious. The mulberry fruit is a multiple fruit 2–3 cm long. Immature fruits are green, or pale yellow. In most species the fruits turn pink and red while ripening dark purple or black, have a sweet flavor when ripe; the fruits of the white-fruited cultivar are white. Although quite similar looking, they are not to be confused with blackberries; the taxonomy of Morus is complex and disputed. Over 150 species names have been published, although differing sources may cite different selections of accepted names, only 10–16 are cited as being accepted by the vast majority of botanical authorities.
Morus classification is further complicated by widespread hybridisation, wherein the hybrids are fertile. The following species are accepted by the Kew Plant List as of August 2015: Black and white mulberry are widespread in southern Europe, the Middle East, northern Africa and Indian subcontinent, where the tree and the fruit have names under regional dialects. Jams and sherbets are made from the fruit in this region. Black mulberry was imported to Britain in the 17th century in the hope that it would be useful in the cultivation of silkworms, it was much used in folk medicine in the treatment of ringworm. Mulberries are widespread in Greece in the Peloponnese, which in the Middle Ages was known as Morea, deriving from the Greek word for the tree. Mulberries can be grown from seed, this is advised as seedling-grown trees are of better shape and health, but they are most planted from large cuttings which root readily; the mulberry plants which are allowed to grow tall with a crown height of 1.5 to 1.8 metres from ground level and a stem girth of 10–13 cm.
They are specially raised with the help of well-grown saplings 8–10 months old of any of the varieties recommended for rainfed areas like S-13 or S-34 which are tolerant to drought or soil-moisture stress conditions. The plantation is raised and in block formation with a spacing of 1.8 by 1.8 m, or 2.4 by 2.4 m, as plant to plant and row to row distance. The plants are pruned once a year during the monsoon season to a height of 1.5–1.8 m and allowed to grow with a maximum of 8–10 shoots at the crown. The leaves are harvested three or four times a year by a leaf-picking method under rain-fed or semiarid conditions, depending on the monsoon; the tree branches pruned during the fall season are cut and used to make durable baskets supporting agriculture and animal husbandry. Some North American cities have banned the planting of mulberries because of the large amounts of pollen they produce, posing a potential health hazard for some pollen allergy sufferers. Only the male mulberry trees produce pollen.
Conversely, female mulberry trees produce all-female flowers, which draw pollen and dust from the air. Because of this pollen-absorbing feature, all-female mulberry trees have an OPALS allergy scale rating of just 1, some consider it "allergy-free". Mulberry tree scion wood can be grafted onto other mulberry trees during the winter, when the tree is dormant. One common scenario is converting a problematic male mulberry tree to an allergy-free female tree, by grafting all-female mulberry tree scions to a male mulberry, pruned back to the trunk. However, any new growth from below the graft must be removed, as they would be from the original male mulberry tree; the fruit of the white mulberry – an East Asian species extensively naturalized in urban regions of eastern North America – has a different flavor, sometimes characterized as refreshing and a little tart, with a bit of gumminess to it and a hint of vanilla. In North America, the white mulberry is considered an invasive exotic and has taken over extensive tracts from native plant species, including the red mulberry.
The ripe fruit is edible and is used in pies, wines and herbal teas. The fruit of the black mulberry and the red mulberry have the strongest flavor, likened to'fireworks in the mouth'; the fruit and leaves are sold in various forms as nutritional supplements. The mature plant contains significant amounts of resveratrol in stem bark. Unripe fruit and green parts of the plant have a white sap that may be toxic, stimulating, or mildly hallucinogenic. In a 100 g serving, raw mulberries provide 180 kJ, 44% of the Daily Value for vitamin C, 14% of the DV for iron. Mulberry leaves those of the white mulberry, are ecologically important as the sole food source of the silkworm, the cocoon of, used to make silk; the wild silk moth eats mulbe