Glossary of botanical terms
This glossary of botanical terms is a list of terms relevant to botany and plants in general. Terms of plant morphology are included here as well as at the related Glossary of plant morphology and Glossary of leaf morphology. See List of Latin and Greek words used in systematic names. You can help by adding illustrations. Ab- A prefix meaning "from, away from, or outside". Abaxial The surface of an organ facing away from the organ's axis, e.g. the lower surface of a lateral organ such as a leaf or petal. Abort To abandon development of a structure or organ. Abscission The shedding of an organ, mature or aged, e.g. a ripe fruit or an old leaf. Abscission zone A specialised layer of tissue that allows an organ to be shed by abscission when it is ripe or senescent. Formed, for example, at the base of a petiole or pedicel. Acaulescent Having no apparent stem, or at least none visible above the ground surface. Examples include some species of Agave and Attalea. Accrescent Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen, for example in Physalis peruviana.
-aceae A suffix added to the stem of a generic name to form the name of a taxonomic family. Achene A dry, 1-seeded indehiscent fruit, e.g. in the genus Ranunculus. Acicular Slender or needle-shaped. Acropetal Moving from roots to leaves, e.g. of molecular signals in plants. Acrophyll The regular leaves of a mature plant, produced above the base. Acrostichoid Covering the entire abaxial surface of a frond densely so, as in Elaphoglossum and Acrostichum. Actino- A prefix that indicates a radial pattern, form, or morphology. Actinodromous Palmate or radially arranged venation with three or more primary veins arising at or near the base of the leaf and either reaching the margin or not. Actinomorphic Regular. Applies e.g. to steles and flowers in which the perianth segments within each whorl are alike in size and shape. Compare regular. Aculeate Armed with prickles, e.g. the stem of a rose. Acuminate Tapering to a point. Acute Sharply pointed. Compare obtuse. Ad- A prefix meaning "near or towards". Adaxial The surface of an organ facing towards the organ's axis, e.g. the upper surface of a lateral organ such as a leaf or petal.
Adnate Grown or fused to an organ of a different kind along a margin, e.g. a stamen fused to a petal. Compare connate. Adventitious A structure produced in an abnormal position, e.g. an adventitious bud produced from a stem rather than from the axil of a leaf. Adventive Introduced accidentally. Aerial Of the air. Aestivation The arrangement of sepals and petals or their lobes in an unexpanded flower bud. Compare vernation, the arrangement of leaves in a bud. aff. With affinity to others, akin to. Aggregate fruit A cluster of fruits formed from the free carpels of one flower, e.g. a blackberry. Compare multiple fruit. Agricultural weed See weed. alate Having a wing or wings. Albumen An older name for the endosperm of flowering plants. Except for being a storage tissue for nutrients, it is not at all like the albumen of animal embryos. Albuminous Containing endosperm. -ales A suffix added to the stem of a generic name or descriptive name to form the name of a taxonomic order. Alien A plant introduced to an area outside its natural range.
Synonymous to or used in combination with foreign, non-native, non-indigenous. Alkaloid A molecule with a nitrogenous base used as a drug, e.g. morphine and strychnine, each of which occurs in certain plants. Alternate 1. Leaves or flowers borne singly including spiralled parts. 2. When something occurs between something else, e.g. stamens alternating with petals. Compare opposite. Ament A synonym of catkin. Amphitropous When the ovule is bent so that both ends are near each other. Compare anatropous and orthotropous. Amplexicaul With the base dilated and clasping the stem of leaves. Anastomose Branching and rejoining, as with leaf venation. Anastomosis A connection or fusion of two or more veins that are diverging or branching, thereby forming a network. Anatropous When an ovule is inverted so that the micropyle faces the placenta. Compare amphitropous, orthotropous. Androdioecious Of plants, having male flowers on separate individuals. Compare andromonoecious, polygamodioecious, polygamomonoecious, polygamous.
Androecium Male parts of flower. Compare gynoecium. Abbreviation: A. For instance A 3+3 indicates 6 stamens in two whorls. Androgynophore A stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth. Androgynous With male and female flowers in the same inflorescence. Androphore The stalk or column supporting the stamens in certain flowers. Andromonoecious Having bisexual flowers and male flowers on the same individual plant. Compare gynomonoecious, polygamodioecious, polygamomonoecious, polygamous. Anemophily Pollination by wind. Angiosperm A flowering plant. Anisomery The condition of hav
Capsule (fruit)
In botany a capsule is a type of simple, though fleshy dehiscent fruit produced by many species of angiosperms. The capsule is derived from a compound ovary. A capsule is a structure composed of two or more carpels. In, the term locule is used to refer to a chamber within the fruit. Depending on the number of locules in the ovary, fruit can be classified as uni-locular, bi-locular, tri-locular or multi-locular; the number of locules present in a gynoecium may be equal to or less than the number of carpels. The locules are separated by septa. In most cases the capsule is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example those of Adansonia digitata and Merciera. Capsules are classified into four types, depending on the type and location of dehiscence. Loculicidal capsules possess longitudinal lines of dehiscence radially aligned with the locules, i.e. not at the septa, along the midrib or dorsal suture of the locules. If septa are absent, the dehiscence lines lie between the placentae.
This type is common among many members of the Liliaceae such as Lilium. Septicidal capsules have dehiscence lines aligned with the sutures of the ovary septa or placentae, between the carpels. Both loculocidal and septicidal capsules split into distinguishable segments called valves; the valves are a part of the pericarp that has split away, without enclosing seeds. The borders of the valves may not coincide with the borders of carpels; these valves may fall off. In septicidal capsules the valves remain in place. In some capsules, the split occurs between carpels, in others each carpel splits open. Circumscissile capsules have a transverse, rather than longitudinal, dehiscence line, so that the upper part of the capsule dehisces forming a terminal lid that opens. An example is Plantago. A variant is the Septifragal capsule in which the outer walls break away from the septa and placentae as valves. Poricidal capsules dehisce through pores in the capsule, as in Papaver, the seeds escaping through these pores.
Examples of other plants that produce capsules include nigella, willow and jimson weed. Some dry dehiscent fruits form specialised capsule-like structures. A follicle is derived from a single carpel that splits along a suture, as in Magnolia, while a legume splits along two sutures, are a defining feature of the Fabaceae; some variants of legumes that have retained vestigial sutures include loments that split transversly into segments, each with a single seed, indehiscent legumes, such as Arachis hypogaea. Capsules derived from two carpels include silicles and siliques that dehisce along two suture lines but retain a partition called the replum, a septum with attached seeds. While both are characteristic of Brassicaceae, silicles is at least as broad as it is long, vice a versa. A schizocarp is derived from a compound ovary with two or more locules which separate radially as one of the above types, such as a schizocarp of follicles, as in Asclepias. A mericarp is a portion of the fruit that separates from the ovary to form a distinct locule unit which encloses the seed, usually-nut-like, as in Apiaceae in which the mericarps are joined by a stalk.
Thus a schizocarp of mericarps is a structure in which the carpels of a single ovary split to form mericarps. A schizocarp of nutlets is derived from a carpel that becomes lobed, the lobes become nutlets that split apart. Examples include Boraginaceae and most Lamiaceae, where the styles are attached between the ovary lobes. Capsules are sometimes mislabeled as nuts, as in the example of the Brazil nut or the Horse-chestnut. A capsule is not a nut because it releases its seeds and it splits apart. Nuts, on the other hand, do not release seeds as they are a compound ovary containing both a single seed and the fruit. Nuts do not split. In the Brazil nut, a lid on the capsule opens, but is too small to release the dozen or so seeds within; these germinate inside the capsule. Fruit
Seed
A seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants. Seeds are the product of the ripened ovule, after fertilization by pollen and some growth within the mother plant; the embryo is developed from the seed coat from the integuments of the ovule. Seeds have been an important development in the reproduction and success of gymnosperm and angiosperm plants, relative to more primitive plants such as ferns and liverworts, which do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates; the term "seed" has a general meaning that antedates the above – anything that can be sown, e.g. "seed" potatoes, "seeds" of corn or sunflower "seeds". In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or husk, whereas the potato is a tuber.
Many structures referred to as "seeds" are dry fruits. Plants producing berries are called baccate. Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the so-called stone fruits have a hardened fruit layer fused to and surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut. Seeds are produced in several related groups of plants, their manner of production distinguishes the angiosperms from the gymnosperms. Angiosperm seeds are produced in a hard or fleshy structure called a fruit that encloses the seeds for protection in order to secure healthy growth; some fruits have layers of both fleshy material. In gymnosperms, no special structure develops to enclose the seeds, which begin their development "naked" on the bracts of cones. However, the seeds do become covered by the cone scales.
Seed production in natural plant populations varies from year to year in response to weather variables and diseases, internal cycles within the plants themselves. Over a 20-year period, for example, forests composed of loblolly pine and shortleaf pine produced from 0 to nearly 5 million sound pine seeds per hectare. Over this period, there were six bumper, five poor, nine good seed crops, when evaluated for production of adequate seedlings for natural forest reproduction. Angiosperm seeds consist of three genetically distinct constituents: the embryo formed from the zygote, the endosperm, triploid, the seed coat from tissue derived from the maternal tissue of the ovule. In angiosperms, the process of seed development begins with double fertilization, which involves the fusion of two male gametes with the egg cell and the central cell to form the primary endosperm and the zygote. Right after fertilization, the zygote is inactive, but the primary endosperm divides to form the endosperm tissue.
This tissue becomes the food the young plant will consume until the roots have developed after germination. After fertilization the ovules develop into the seeds; the ovule consists of a number of components: The funicle or seed stalk which attaches the ovule to the placenta and hence ovary or fruit wall, at the pericarp. The nucellus, the remnant of the megasporangium and main region of the ovule where the megagametophyte develops; the micropyle, a small pore or opening in the apex of the integument of the ovule where the pollen tube enters during the process of fertilization. The chalaza, the base of the ovule opposite the micropyle, where integument and nucellus are joined together; the shape of the ovules as they develop affects the final shape of the seeds. Plants produce ovules of four shapes: the most common shape is called anatropous, with a curved shape. Orthotropous ovules are straight with all the parts of the ovule lined up in a long row producing an uncurved seed. Campylotropous ovules have a curved megagametophyte giving the seed a tight "C" shape.
The last ovule shape is called amphitropous, where the ovule is inverted and turned back 90 degrees on its stalk. In the majority of flowering plants, the zygote's first division is transversely oriented in regards to the long axis, this establishes the polarity of the embryo; the upper or chalazal pole becomes the main area of growth of the embryo, while the lower or micropylar pole produces the stalk-like suspensor that attaches to the micropyle. The suspensor absorbs and manufactures nutrients from the endosperm that are used during the embryo's growth; the main components of the embryo are: The cotyledons, the seed leaves, attached to the embryonic axis. There may be two; the cotyledons are the source of nutrients in the non-endospermic dicotyledons, in which case they replace the endosperm, are thick and leathery. In endospermic seeds the cotyledons are papery. Dicotyledons have the point of attachment opposite one another on the axis; the epicotyl, the embryonic axis above the point of attachment of the cotyledon.
The plumule, the tip of the epicotyl, has a feathery appearance due to the presence of young leaf primordia at the apex, will become the shoot upon germination. The hypocotyl, the embryonic axis below the point of attachment of the cotyledon, connecting the epicotyl and the radicle, being the stem-root transition zone; the radicle, the basal tip of the hy
William Jackson Hooker
Sir William Jackson Hooker was an English systematic botanist and organiser, botanical illustrator. He held the post of Regius Professor of Botany at Glasgow University, was Director of the Royal Botanic Gardens, Kew, he enjoyed the friendship and support of Sir Joseph Banks for his exploring and organising work. His son, Joseph Dalton Hooker, succeeded him to the Directorship of Kew Gardens. Hooker was born in Norwich, his father, Joseph Hooker of Exeter, a member of the same family as the celebrated theologian Richard Hooker, devoted much of his time to the study of German literature and the cultivation of curious plants. He was educated at Norwich School and afterwards took up as a recreation the study of natural history ornithology and entomology, he subsequently confined his attention to botany, on the recommendation of Sir James Edward Smith, whom he had consulted respecting a rare moss. Hooker inherited enough money to be able to travel at his own expense, his first botanical expedition—at the suggestion of Sir Joseph Banks—was to Iceland, in the summer of 1809.
The specimens he collected, along with his notes and drawings, were destroyed by fire on the homeward voyage. His good memory, aided him to publish an account of the island, of its inhabitants and flora. In 1810–1811 he made extensive preparations, sacrifices which proved financially serious, with a view to accompany Sir Robert Brownrigg to Ceylon, but political upheaval led to the project being abandoned. In 1814 he spent nine months in botanizing excursions in France and northern Italy, in the following year he married Maria Dawson Turner, the eldest daughter of Dawson Turner, banker, of Great Yarmouth, sister-in-law of Francis Palgrave. Settling at Halesworth, Suffolk, he devoted himself to the formation of his herbarium, which became of worldwide renown among botanists. In 1816 the British Jungermanniae, his first scientific work, was published; this was succeeded by a new edition of William Curtis's Flora Londinensis, for which he wrote the descriptions. In 1820 he accepted the regius professorship of botany in the University of Glasgow where he soon became popular as a lecturer.
The following year he brought out the Flora Scotica, in which the natural method of arrangement of British plants was given with the artificial. He worked with the Glasgow botanist and lithographer Thomas Hopkirk to establish the Royal Botanic Institution of Glasgow and to lay out and develop the Glasgow Botanic Gardens. In 1815, he was made a corresponding member of the Royal Swedish Academy of Sciences, and, in 1833, his status was changed to that of foreign member, he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1823. Hooker succeeded in convincing the British government that botanists should be appointed to their expeditions. While his works were in progress his herbarium received large and valuable additions from all parts of the globe, his position as a botanist was thus vastly improved, he was made a Knight of the Royal Guelphic Order and a Knight Bachelor in 1836, in 1841 he was appointed director of the Royal Botanic Gardens, Kew, on the resignation of William Townsend Aiton.
Under his direction the gardens expanded from 10 to 75 acres, with an arboretum of 270 acres, many new glass-houses were erected, a museum of economic botany was established. He was engaged on the Synopsis filicum with John Gilbert Baker when he contracted a throat infection epidemic at Kew, he is buried at St. Anne's Church, Kew, he was succeeded at Kew Gardens by his son Sir Joseph Dalton Hooker, a rare example of an outstanding man succeeded in his post by an outstanding son. Exotic Flora, indicating such of the specimens as are deserving cultivation Account of Sabine's Arctic Plants Catalogue of Plants in the Glasgow Botanic Garden Botany of Parry's Third Voyage Curtis's Botanical Magazine Icones Filicum, in concert with Dr R. K. Greville British Flora, of which several editions appeared, undertaken with Dr G. A. W. Arnott, &c. British Flora Cryptogamia Characters of Genera from the British Flora Flora Boreali-Americana, being the botany of British North America collected in Sir John Franklin's voyage The Journal of Botany Companion to the Botanical Magazine Icones Plantarum Botany of Beechey's Voyage to the Pacific and Behring's Straits Genera Filicum, from the original coloured drawings of F. Bauer, with additions and descriptive letterpress The London Journal of Botany Notes on the Botany of the Antarctic Voyage of the Erebus and Terror Species Filicum, the standard work on this subject A Century of Orchidaceous Plants Hooker's Journal of Botany and Kew Garden Miscellany Niger Flora Victoria Regia A Century of Ferns Museums of Economic Botany at Kew Filices Exoticae The Br
Cultivar
The term cultivar most refers to an assemblage of plants selected for desirable characters that are maintained during propagation. More cultivar refers to the most basic classification category of cultivated plants in the International Code of Nomenclature for Cultivated Plants. Most cultivars arose in cultivation. Popular ornamental garden plants like roses, daffodils and azaleas are cultivars produced by careful breeding and selection for floral colour and form; the world's agricultural food crops are exclusively cultivars that have been selected for characters such as improved yield and resistance to disease, few wild plants are now used as food sources. Trees used in forestry are special selections grown for their enhanced quality and yield of timber. Cultivars form a major part of Liberty Hyde Bailey's broader group, the cultigen, defined as a plant whose origin or selection is due to intentional human activity. A cultivar is not the same as a botanical variety, a taxonomic rank below subspecies, there are differences in the rules for creating and using the names of botanical varieties and cultivars.
In recent times, the naming of cultivars has been complicated by the use of statutory patents for plants and recognition of plant breeders' rights. The International Union for the Protection of New Varieties of Plants offers legal protection of plant cultivars to persons or organisations that introduce new cultivars to commerce. UPOV requires that a cultivar be "distinct, uniform", "stable". To be "distinct", it must have characters that distinguish it from any other known cultivar. To be "uniform" and "stable", the cultivar must retain these characters in repeated propagation; the naming of cultivars is an important aspect of cultivated plant taxonomy, the correct naming of a cultivar is prescribed by the Rules and Recommendations of the International Code of Nomenclature for Cultivated Plants. A cultivar is given a cultivar name, which consists of the scientific Latin botanical name followed by a cultivar epithet; the cultivar epithet is in a vernacular language. For example, the full cultivar name of the King Edward potato is Solanum tuberosum'King Edward'.'King Edward' is the cultivar epithet, according to the Rules of the Cultivated Plant Code, is bounded by single quotation marks.
The word cultivar originated from the need to distinguish between wild plants and those with characteristics that arose in cultivation, presently denominated cultigens. This distinction dates to the Greek philosopher Theophrastus, the "Father of Botany", keenly aware of this difference. Botanical historian Alan Morton noted that Theophrastus in his Historia Plantarum "had an inkling of the limits of culturally induced changes and of the importance of genetic constitution"; the International Code of Nomenclature for algae and plants uses as its starting point for modern botanical nomenclature the Latin names in Linnaeus' Species Plantarum and Genera Plantarum. In Species Plantarum, Linnaeus enumerated all plants known to him, either directly or from his extensive reading, he recognised the rank of varietas and he indicated these varieties with letters of the Greek alphabet, such as α, β, λ, before the varietal name, rather than using the abbreviation "var." as is the present convention. Most of the varieties that Linnaeus enumerated were of "garden" origin rather than being wild plants.
In time the need to distinguish between wild plants and those with variations, cultivated increased. In the nineteenth century many "garden-derived" plants were given horticultural names, sometimes in Latin and sometimes in a vernacular language. From circa the 1900s, cultivated plants in Europe were recognised in the Scandinavian and Slavic literature as stamm or sorte, but these words could not be used internationally because, by international agreement, any new denominations had to be in Latin. In the twentieth century an improved international nomenclature was proposed for cultivated plants. Liberty Hyde Bailey of Cornell University in New York, United States created the word cultivar in 1923 when he wrote that: The cultigen is a species, or its equivalent, that has appeared under domestication – the plant is cultigenous. I now propose another name, for a botanical variety, or for a race subordinate to species, that has originated under cultivation, it is the equivalent of the botanical variety except in respect to its origin.
In that essay, Bailey used only the rank of species for the cultigen, but it was obvious to him that many domesticated plants were more like botanical varieties than species, that realization appears to have motivated the suggestion of the new category of cultivar. Bailey created the word cultivar, assumed to be a portmanteau of cultivated and variety. Bailey never explicitly stated the etymology of cultivar, it has been suggested that it is instead a contraction of cultigen and variety, which seems correct; the neologism cultivar was promoted as "euphonious" and "free from ambiguity". The first Cultivated Plant Code of 1953 subsequently commended its use, by 1960 it had achieved common international acceptance; the words cultigen and cultivar may be confused with
Portulaca oleracea
Portulaca oleracea is an annual succulent in the family Portulacaceae, which may reach 40 cm in height. Forty cultivars are grown, it has an extensive distribution, assumed to be anthropogenic, extending from North Africa and Southern Europe through the Middle East and the Indian subcontinent to Malesia and Australasia. The species status in the Americas is uncertain: in general, it is considered an exotic weed, there is evidence that the species was in Crawford Lake deposits in 1350–1539, suggesting that it reached North America in the pre-Columbian era. Scientists suggested that the plant was eaten by native Americans, who spread its seeds. How it reached the Americas is unknown, it has smooth, reddish prostrate stems and the leaves, which may be alternate or opposite, are clustered at stem joints and ends. The yellow flowers are up to 6 mm wide. Depending upon rainfall, the flowers appear at any time during the year; the flowers open singly at the center of the leaf cluster for only a few hours on sunny mornings.
Seeds are formed in a tiny pod. Purslane has a taproot with fibrous secondary roots and is able to tolerate poor compacted soils and drought. Used in East Mediterranean countries, archaeobotanical finds are common at many prehistoric sites. In historic contexts, seeds have been retrieved from a protogeometric layer in Kastanas, as well as from the Samian Heraion dating to seventh century BC. In the fourth century BC, Theophrastus names purslane, andrákhne, as one of the several summer pot herbs that must be sown in April; as Portulaca it figures in the long list of comestibles enjoyed by the Milanese given by Bonvesin de la Riva in his "Marvels of Milan". In antiquity, its healing properties were thought so reliable that Pliny the Elder advised wearing the plant as an amulet to expel all evil. Purslane may be eaten as a leaf vegetable. William Cobbett noted that it was "eaten by pigs when they can get nothing else. Both use it in salad, to say, raw", it has a sour and salty taste and is eaten throughout much of Europe, the Middle East and Mexico.
The stems and flower buds are all edible. Purslane may be used fresh as a salad, stir-fried, or cooked as spinach is, because of its mucilaginous quality it is suitable for soups and stews; the sour taste is due to oxalic and malic acid, the latter of, produced through the crassulacean acid metabolism pathway, seen in many xerophytes, is at its highest when the plant is harvested in the early morning. Australian Aborigines use the seeds of purslane to make seedcakes. Greeks, who call it andrákla or glistrída, use the leaves and the stems with feta cheese, onion, garlic and olive oil, they add it to casseroled chicken. In Turkey, besides being used in salads and in baked pastries, it is cooked as a vegetable similar to spinach, or is mixed with yogurt to form a Tzatziki variant; as a companion plant, purslane provides ground cover to create a humid microclimate for nearby plants, stabilising ground moisture. Its deep roots bring up moisture and nutrients that those plants can use, some, including corn, will follow purslane roots down through harder soil that they cannot penetrate on their own.
Purslane contains more omega-3 fatty acids than any other leafy vegetable. Studies have found, it contains vitamins, dietary minerals such as magnesium, calcium and iron. Present are two types of betalain alkaloid pigments, the reddish betacyanins and the yellow betaxanthins. Both of these pigment types are potent antioxidants and have been found to have antimutagenic properties in laboratory studies. 100 grams of fresh purslane leaves contain 300 to 400 mg of alpha-linolenic acid. One cup of cooked leaves contains 90 mg of calcium, 561 mg of potassium, more than 2,000 IUs of vitamin A; when water is abundant, purslane performs photosynthesis by C3 carbon fixation, more widespread in nature. When stressed by low availability of water, purslane, which has evolved in hot and dry environments, switches to photosynthesis using an alternative pathway, crassulacean acid metabolism. At night its leaves trap carbon dioxide, converted into malic acid, and, in the day, the malic acid is converted into glucose.
When harvested in the early morning, the leaves have ten times the malic acid content as when harvested in the late afternoon, thus have a more tangy taste. Opuntia cacti, which are eaten as a vegetable employ the CAM pathway and are best harvested in the late afternoon, though the pickled nopales sold commercially have citric or malic acids added to the pickling liquid. Chemical constituents include noradrenaline, calcium salts, dopamine, L-DOPA, malic acid, citric acid, glutamic acid, asparagic acid, nicotinic acid, glucose and sucrose. Purslane contains oxalic acid that makes it non-recommended in large quantities for people who have uric acid or kidney problems or must restrict dietary oxalate levels. Betacyanins isolated from Portulaca oler
