Leaf in the context of "Devonian"

⭐ In the context of the Devonian period, the development of leaves on vascular plants is most directly associated with…

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⭐ Core Definition: Leaf

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 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. The leaf is an integral part of the stem system, and 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 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 vary in shape, size, texture and color, depending on the species The broad, flat leaves with complex venation of flowering plants are known as megaphylls and 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 the phyllids of mosses and liverworts.

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👉 Leaf in the context of Devonian

The Devonian (/dəˈvni.ən, dɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at 419.62 million years ago (Ma), to the beginning of the succeeding Carboniferous period at 358.86 Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied.

The first significant evolutionary radiation of life on land occurred during the Devonian, as free-sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants (pteridospermatophytes) appeared. This rapid evolution and colonization process, which had begun during the Silurian, is known as the Silurian-Devonian Terrestrial Revolution. The earliest land animals, predominantly arthropods such as myriapods, arachnids and hexapods, also became well-established early in this period, after beginning their colonization of land at least from the Ordovician Period.

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Leaf in the context of Painting

Painting is a visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "support"). The medium is commonly applied to the base with a brush. Other implements, such as palette knives, sponges, airbrushes, the artist's fingers, or even a dripping technique that uses gravity may be used. One who produces paintings is called a painter.

In art, the term "painting" describes both the act and the result of the action (the final work is called "a painting"). The support for paintings includes such surfaces as walls, paper, canvas, wood, glass, lacquer, pottery, leaf, copper and concrete, and the painting may incorporate other materials, in single or multiple form, including sand, clay, paper, cardboard, newspaper, plaster, gold leaf, and even entire objects.

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Leaf in the context of Evergreen

In botany, an evergreen is a plant which has foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many different species, the unique feature of evergreen plants lends itself to various environments and purposes.

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Leaf in the context of Olea

Olea (/ˈliə/ OH-lee-ə) is a genus of flowering plants in the family Oleaceae. It includes 12 species native to warm temperate and tropical regions of the Middle East, southern Europe, Africa, southern Asia, and Australasia. They are evergreen trees and shrubs, with small, opposite, entire leaves. The fruit is a drupe. Leaves of Olea contain trichosclereids.

For humans, the most important and familiar species is by far the olive (Olea europaea), native to the Mediterranean region, Africa, southwest Asia, and the Himalayas, which is the type species of the genus. The native olive (O. paniculata) is a larger tree, attaining a height of 15–18 m in the forests of Queensland, and yielding a hard and tough timber. The yet harder wood of the black ironwood O. capensis, an inhabitant of Natal, is important in South Africa.

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Leaf in the context of Wood

Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. Being a natural material, it is characterized as an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin and hemicelluloses that resists compression.

Wood is sometimes defined as only the secondary xylem in the stems of trees, or more broadly to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree, it performs a mechanical-support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients among the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips, or fibers.

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Leaf in the context of Autumn

Autumn, also known as fall in North American English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, beginning in September (Northern Hemisphere) or March (Southern Hemisphere). Autumn is the season when the duration of daytime becomes noticeably shorter and the temperature cools considerably. Day length decreases and night length increases as the season progresses until the winter solstice in December (Northern Hemisphere) and June (Southern Hemisphere). One of its main features in temperate climates is the striking change in colour of the leaves of deciduous trees as they prepare to shed.

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Leaf in the context of Herbs

Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distinguishes herbs from spices. Herbs generally refers to the leafy green or flowering parts of a plant (either fresh or dried), while spices are usually dried and produced from other parts of the plant, including seeds, bark, roots and fruits.

Herbs have a variety of uses including culinary, medicinal, aromatic and in some cases, spiritual. General usage of the term "herb" differs between culinary herbs and medicinal herbs; in medicinal or spiritual use, any parts of the plant might be considered "herbs", including leaves, roots, flowers, seeds, root bark, inner bark (and cambium), resin and pericarp.

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Leaf in the context of Wreath

A wreath (/rθ/) is an assortment of flowers, leaves, fruits, twigs, or various materials that is constructed to form a ring shape.

In English-speaking countries, wreaths are used typically as household ornaments, most commonly as an Advent and Christmas decoration. They are also used in ceremonial events in many cultures around the globe. They can be worn as a chaplet around the head, or as a garland around the neck.

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Leaf in the context of Taxodium

Taxodium /tækˈsdiəm/ is a genus of one to three species (depending on taxonomic opinion) of extremely flood-tolerant conifers in the cypress family, Cupressaceae. The name is derived from the Latin word taxus, meaning "yew", and the Greek word εἶδος (eidos), meaning "similar to." Within the family, Taxodium is most closely related to Chinese swamp cypress (Glyptostrobus pensilis) and sugi (Cryptomeria japonica).

Species of Taxodium occur in the southern part of the North American continent and are deciduous in the north and semi-evergreen to evergreen in the south. They are large trees, reaching 100–150 ft (30–46 m) tall and 6.5–10 ft (2–3 m) (exceptionally 36 ft or 11 m) trunk diameter. The needle-like leaves, 0.2–0.8 in (0.5–2 cm) long, are borne spirally on the shoots, twisted at the base so as to appear in two flat rows on either side of the shoot. The cones are globose, 0.8–1.4 in (2–3.5 cm) diameter, with 10–25 scales, each scale with one or two seeds; they are mature in 7–9 months after pollination, when they disintegrate to release the seeds. The male (pollen) cones are produced in pendulous racemes, and shed their pollen in early spring. Taxodium species grow cypress knees, when growing in or beside water. The function of these knees is currently a subject of ongoing research.

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