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Rhamnus (plant)
''Rhamnus'' is a genus of about 140 accepted species of shrubs or small trees, commonly known as buckthorns, in the family Rhamnaceae. Its species range from tall (rarely to ) and are native mainly in east Asia and North America, but found throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America. One species, the common buckthorn (''Rhamnus cathartica''), is able to flourish as an invasive species, invasive plant in parts of Canada and the United States, where it has become naturalisation (biology), naturalized. Both deciduous and evergreen species occur. The leaves are simple, long, and arranged alternately, in opposite pairs, or almost paired (subopposite). One distinctive character of many buckthorns is the way the venation (botany), veination curves upward towards the tip of the leaf. The plant bears fruits which are black or red berry-like drupes. The name is due to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhamnus Cathartica
''Rhamnus cathartica'', the European buckthorn, common buckthorn, purging buckthorn, or just buckthorn, is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan. It was introduced to North America as an ornamental shrub in the early 19th century or perhaps before, and is now naturalisation (biology), naturalized in the northern half of the continent, and is classified as an invasive plant in several US states and in Ontario, Canada. Description ''Rhamnus cathartica'' is a deciduous, dioecious shrub or small tree growing up to tall, with grey-brown bark and often thorny branches. The leaf, leaves are elliptic to oval, long and broad; they are green, turning yellow in autumn, have toothed margins, and are arranged somewhat variably in opposite to subopposite pairs or alternately. The flowers are yellowish-green with four petals; they ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naturalisation (biology)
Naturalisation (or naturalization) is the ecological phenomenon through which a species, taxon, or population of exotic (as opposed to native) origin integrates into a given ecosystem, becoming capable of reproducing and growing in it, and proceeds to disseminate spontaneously. In some instances, the presence of a species in a given ecosystem is so ancient that it cannot be presupposed whether it is native or introduced. Generally, any introduced species may (in the wild) either go extinct or naturalise in its new environment. Some populations do not sustain themselves reproductively, but exist because of continued influx from elsewhere. Such a non-sustaining population, or the individuals within it, are said to be adventive. Cultivated plants, sometimes called nativars, are a major source of adventive populations. Botany In botany, naturalisation is the situation in which an exogenous plant reproduces and disperses on its own in a new environment. For exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panicle
In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are often racemes. A panicle may have determinate or indeterminate growth. This type of inflorescence is largely characteristic of grasses, such as oat and crabgrass, as well as other plants such as pistachio and mamoncillo. Botanists use the term paniculate in two ways: "having a true panicle inflorescence" as well as "having an inflorescence with the form but not necessarily the structure of a panicle". Corymb A corymb may have a paniculate branching structure, with the lower flowers having longer pedicels than the upper, thus giving a flattish top superficially resembling an umbel. Many species in the subfamily Amygdaloideae, such as hawthorns and rowans, produce their flowers in corymbs. up'' Sorbus glabrescens'' co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raceme
A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the shoot grows in height, with no predetermined growth limit. Examples of racemes occur on mustard (genus ''Brassica''), radish (genus ''Raphanus''), and orchid (genus ''Phalaenopsis'') plants. Definition A ''raceme'' or ''racemoid'' is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing pedicellate flowers (flowers having short floral stalks called ''Pedicel (botany), pedicels'') along its axis. In botany, an ''axis'' means a shoot, in this case one bearing the flowers. In indeterminate inflorescence-like racemes, the oldest flowers grow close to the base and new flowers are produced as the shoot grows in height, with no predetermined growth limit. A plant that flowers on a showy raceme may hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyme (botany)
In botany, an inflorescence is a group or cluster of flowers arranged on a plant's stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a main axis ( peduncle) and by the timing of its flowering (determinate and indeterminate). Morphologically, an inflorescence is the modified part of the shoot of seed plants where flowers are formed on the axis of a plant. The modifications can involve the length and the nature of the internodes and the phyllotaxis, as well as variations in the proportions, compressions, swellings, adnations, connations and reduction of main and secondary axes. One can also define an inflorescence as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern. General characteristics Inflorescences are described by many different characteristics including how the flowers are arranged on the peduncle, the blooming order of the flowe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Reproductive Morphology
Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction. Among all living organisms, flowers, which are the reproductive structures of angiosperms, are the most varied physically and show a correspondingly great diversity in methods of reproduction. Plants that are not flowering plants ( green algae, mosses, liverworts, hornworts, ferns and gymnosperms such as conifers) also have complex interplays between morphological adaptation and environmental factors in their sexual reproduction. The breeding system, or how the sperm from one plant fertilizes the ovum of another, depends on the reproductive morphology, and is the single most important determinant of the genetic structure of nonclonal plant populations. Christian Konrad Sprengel (1793) studied the reproduction of flowering plants and for the first time it was understood that the pollination proce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flower
Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, modified leaves; corolla, the petals; androecium, the male reproductive unit consisting of stamens and pollen; and gynoecium, the female part, containing style and stigma, which receives the pollen at the tip of the style, and ovary, which contains the ovules. When flowers are arranged in groups, they are known collectively as inflorescences. Floral growth originates at stem tips and is controlled by MADS-box genes. In most plant species flowers are heterosporous, and so can produce sex cells of both sexes. Pollination mediates the transport of pollen to the ovules in the ovaries, to facilitate sexual reproduction. It can occur between different plants, as in cross-pollination, or between flowers on the same plant or even the same f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecy
Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only the female part of the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. In zoology In zoology, dioecy means that an animal is either male or female, in which case the synonym gonochory is more often used. Most animal species are gonochoric, almost all vertebrate species are gonochoric, and all bird and mammal species are gonochoric. Dioecy may also describe colonies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branch
A branch, also called a ramus in botany, is a stem that grows off from another stem, or when structures like veins in leaves are divided into smaller veins. History and etymology In Old English, there are numerous words for branch, including , , , and . There are also numerous descriptive words, such as (that is, something that has bled, or 'bloomed', out), (literally 'little bough'), (literally 'on growth'), and (literally 'offspringing'). Numerous other words for twigs and boughs abound, including , which still survives as the ''-toe'' in ''mistletoe''. Latin words for branch are or . The latter term is an affix found in other modern words such as '' cladodont'' (prehistoric sharks with branched teeth), ''cladode'' (flattened leaf-like branches), or ''cladogram'' (a branched diagram showing relations among organisms). Woody branches Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually refers to a terminus, while ''bou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf
A leaf (: leaves) is a principal appendage of the plant stem, 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 (botany), shoot system. In most leaves, the primary Photosynthesis, photosynthetic Tissue (biology), 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 (Glossary of botanical terms#adaxial, adaxial) and lower (Glossary of botanical terms#abaxial, abaxial) surfaces that differ in color, Trichome, hairiness, the number of stomata (pores that intake and output gases), the amount and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drupe
In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed (''kernel'') inside. Drupes do not split open to release the seed, i.e., they are dehiscence (botany), indehiscent. These fruits usually develop from a single carpel, and mostly from flowers with Superior ovary, superior ovaries (polypyrenous drupes are exceptions). The definitive characteristic of a drupe is that the hard, woody (lignified) stone is derived from the Ovary (botany), ovary wall of the flower. In an aggregate fruit, which is composed of small, individual drupes (such as a raspberry), each individual is termed a drupelet, and may together form an aggregate fruit. Such fruits are often termed ''berries'', although botanists use a Berry (botany), different definition of ''berry''. Other fleshy fruits may have a stony enclosur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venation (botany)
A leaf (: 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 w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
