Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word xylem is derived from the Ancient Greek word ξύλον (xylon), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858.
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the soil, but roots can also be aerial or aerating, that is, growing up above the ground or especially above water.
In botany, a stoma, also called a stomate, is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that regulate the size of the stomatal opening.
Potassium deficiency, also known as potash deficiency, is a plant disorder that is most common on light, sandy soils, because potassium ions (K+) are highly soluble and will easily leach from soils without colloids. Potassium deficiency is also common in chalky or peaty soils with a low clay content. It is also found on heavy clays with a poor structure.
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes the innermost layer of the periderm. The outer bark on older stems includes the dead tissue on the surface of the stems, along with parts of the outermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the living periderm is also called the rhytidome.
Cork cambium is a tissue found in many vascular plants as a part of the epidermis. It is one of the many layers of bark, between the cork and primary phloem. The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems. It is found in woody and many herbaceous dicots, gymnosperms and some monocots. It is one of the plant's meristems – the series of tissues consisting of embryonic disk cells from which the plant grows. The function of cork cambium is to produce the cork, a tough protective material.
In botany, a pome is a type of fruit produced by flowering plants in the subtribe Malinae of the family Rosaceae. Pome fruits consist of a central "core" containing multiple small seeds, which is enveloped by a tough membrane and surrounded by an edible layer of flesh. Pome fruit trees are deciduous, and undergo a dormant winter period that requires cold temperatures to break dormancy in spring. Well-known pomes include the apple, pear, and quince.
The Rhizophoraceae is a family of tropical or subtropical flowering plants. It includes around 147 species distributed in 15 genera. Under the family, there are three tribes, Rhizophoreae, Gynotrocheae, and Macarisieae. Even though Rhizophoraceae is known for its mangrove members, only the genera under Rhizophoreae grow in the mangrove habitats and the remaining members live in inland forests.
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids (Orchidaceae), tropical coastal swamp trees such as mangroves, banyan figs, the warm-temperate rainforest rata, and pohutukawa trees of New Zealand. Vines such as common ivy and poison ivy also have aerial roots.
Suberin, cutin and lignins are complex, higher plant epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids called suberin acids, and glycerol. Suberins and lignins are considered covalently linked to lipids and carbohydrates, respectively, and lignin is covalently linked to suberin, and to a lesser extent, to cutin. Suberin is a major constituent of cork, and is named after the cork oak, Quercus suber. Its main function is as a barrier to movement of water and solutes.
In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. The outer cortical cells often acquire irregularly thickened cell walls, and are called collenchyma cells.
The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three types based on the nature of the cell walls.
- Parenchyma cells have thin primary walls and usually remain alive after they become mature. Parenchyma forms the "filler" tissue in the soft parts of plants, and is usually present in cortex, pericycle, pith, and medullary rays in primary stem and root.
- Collenchyma cells have thin primary walls with some areas of secondary thickening. Collenchyma provides extra mechanical and structural support, particularly in regions of new growth.
- Sclerenchyma cells have thick lignified secondary walls and often die when mature. Sclerenchyma provides the main structural support to a plant.
The epidermis is a single layer of cells that covers the leaves, flowers, roots and stems of plants. It forms a boundary between the plant and the external environment. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and absorbs water and mineral nutrients. The epidermis of most leaves shows dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. Woody stems and some other stem structures such as potato tubers produce a secondary covering called the periderm that replaces the epidermis as the protective covering.
This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens. This page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is also an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, and organized by plant anatomy and function in plant physiology.
Lepidodendrales or arborescent lycophytes are an extinct group of primitive, vascular, heterosporous, arborescent (tree-like) plants belonging to Lycopodiopsida. Members of Lepidodendrales are the best understood of the fossil lycopsids due to the vast diversity of Lepidodendrales specimens and the diversity in which they were preserved; the extensive distribution of Lepidodendrales specimens as well as their well-preservedness lends paleobotanists exceptionally detailed knowledge of the coal-swamp giants’ reproductive biology, vegetative development, and role in their paleoecosystem. The defining characteristics of the Lepidodendrales are their secondary xylem, extensive periderm development, three-zoned cortex, rootlike appendages known as stigmarian rootlets arranged in a spiralling pattern, and megasporangium each containing a single functional megaspore that germinates inside the sporangium. Many of these different plant organs have been assigned both generic and specific names as relatively few have been found organically attached to each other. Some specimens have been discovered which indicate heights of 40 and even 50 meters and diameters of over 2 meters at the base. The massive trunks of some species branched profusely, producing large crowns of leafy twigs; though some leaves were up to 1 meter long, most were much shorter, and when leaves dropped from branches their conspicuous leaf bases remained on the surface of branches. Strobili could be found at the tips of distal branches or in an area at the top of the main trunk. The underground organs of Lepidodendrales typically consisted of dichotomizing axes bearing helically arranged, lateral appendages serving an equivalent function to roots. Sometimes called "giant club mosses", they are believed to be more closely related to extant quillworts based on xylem, although fossil specimens of extinct Selaginellales from the Late Carboniferous also had secondary xylem.
A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. 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. In wider definitions, the taller palms, tree ferns, bananas, and bamboos are also trees.
A cambium, in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from which phloem, xylem, or cork grows by division, resulting in secondary thickening. It forms parallel rows of cells, which result in secondary tissues.
Hypericum sechmenii, commonly called seçmen kantaronu in Turkish which means Seçmen's St. John's wort in English, is a rare species of flowering plant of the St. John's wort family (Hypericaceae) that is found only in the Eskişehir Province of central Turkey. It was described by Turkish botanists Atila Ocak and Onur Koyuncu who named the species in honor of Özcan Seçmen, a fellow Turkish botanist. Found in the crevices of exposed limestone, it is a perennial herb which grows in clusters of stems 3–6 centimetres tall and blooms June to July with bright yellow five-petalled flowers. Formally described in 2009, the species was first collected in 2006 and has since been found in only two localities with an estimated population of less than 250.
Ethylene (CH
2=CH
2) is an unsaturated hydrocarbon gas (alkene) acting as a naturally occurring plant hormone. It is the simplest alkene gas and is the first gas known to act as hormone. It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, the abscission (or shedding) of leaves and, in aquatic and semi-aquatic species, promoting the 'escape' from submergence by means of rapid elongation of stems or leaves. This escape response is particularly important in rice farming. Commercial fruit-ripening rooms use "catalytic generators" to make ethylene gas from a liquid supply of ethanol. Typically, a gassing level of 500 to 2,000 ppm is used, for 24 to 48 hours. Care must be taken to control carbon dioxide levels in ripening rooms when gassing, as high temperature ripening (20 °C; 68 °F) has been seen to produce CO2 levels of 10% in 24 hours.
