Plant anatomy or phytotomy is the general term for the study of the internal structure of plants. Originally it included plant morphology, the description of the physical form and external structure of plants, but since the mid-20th century plant anatomy has been considered a separate field referring only to internal plant structure. Plant anatomy is now frequently investigated at the cellular level, and often involves the sectioning of tissues and microscopy.
Some studies of plant anatomy use a systems approach, organized on the basis of the plant's activities, such as nutrient transport, flowering, pollination, embryogenesis or seed development.  Others are more classically divided into the following structural categories:
About 300 BC Theophrastus wrote a number of plant treatises, only two of which survive, Enquiry into Plants (Περὶ φυτῶν ἱστορία), and On the Causes of Plants (Περὶ φυτῶν αἰτιῶν). He developed concepts of plant morphology and classification, which did not withstand the scientific scrutiny of the Renaissance.
A Swiss physician and botanist, Gaspard Bauhin, introduced binomial nomenclature into plant taxonomy. He published Pinax theatri botanici in 1596, which was the first to use this convention for naming of species. His criteria for classification included natural relationships, or 'affinities', which in many cases were structural.
It was in the late 1600s that plant anatomy became refined into a modern science. Italian doctor and microscopist, Marcello Malpighi, was one of the two founders of plant anatomy. In 1671 he published his Anatomia Plantarum, the first major advance in plant physiogamy since Aristotle. The other founder was the British doctor Nehemiah Grew. He published An Idea of a Philosophical History of Plants in 1672 and The Anatomy of Plants in 1682. Grew is credited with the recognition of plant cells, although he called them 'vesicles' and 'bladders'. He correctly identified and described the sexual organs of plants (flowers) and their parts.
In the eighteenth century, Carl Linnaeus established taxonomy based on structure, and his early work was with plant anatomy. While the exact structural level which is to be considered to be scientifically valid for comparison and differentiation has changed with the growth of knowledge, the basic principles were established by Linnaeus. He published his master work, Species Plantarum in 1753.
In 1802, French botanist Charles-François Brisseau de Mirbel, published Traité d'anatomie et de physiologie végétale (Treatise on Plant Anatomy and Physiology) establishing the beginnings of the science of plant cytology.
In 1812, Johann Jacob Paul Moldenhawer published Beyträge zur Anatomie der Pflanzen, describing microscopic studies of plant tissues.
In 1813 a Swiss botanist, Augustin Pyrame de Candolle, published Théorie élémentaire de la botanique, in which he argued that plant anatomy, not physiology, ought to be the sole basis for plant classification. Using a scientific basis, he established structural criteria for defining and separating plant genera.
In 1830, Franz Meyen published Phytotomie, the first comprehensive review of plant anatomy.
In 1838 German botanist Matthias Jakob Schleiden, published Contributions to Phytogenesis, stating, "the lower plants all consist of one cell, while the higher plants are composed of (many) individual cells" thus confirming and continuing Mirbel's work.
A German-Polish botanist, Eduard Strasburger, described the mitotic process in plant cells and further demonstrated that new cell nuclei can only arise from the division of other pre-existing nuclei. His Studien über Protoplasma was published in 1876.
Gottlieb Haberlandt, a German botanist, studied plant physiology and classified plant tissue based upon function. On this basis, in 1884 he published Physiologische Pflanzenanatomie (Physiological Plant Anatomy) in which he described twelve types of tissue systems (absorptive, mechanical, photosynthetic, etc.).
British paleobotanists Dunkinfield Henry Scott and William Crawford Williamson described the structures of fossilized plants at the end of the nineteenth century. Scott's Studies in Fossil Botany was published in 1900.
Following Charles Darwin's Origin of Species a Canadian botanist, Edward Charles Jeffrey, who was studying the comparative anatomy and phylogeny of different vascular plant groups, applied the theory to plants using the form and structure of plants to establish a number of evolutionary lines. He published his The Anatomy of Woody Plants in 1917.
The growth of comparative plant anatomy was spearheaded by British botanist Agnes Arber. She published Water Plants: A Study of Aquatic Angiosperms in 1920, Monocotyledons: A Morphological Study in 1925, and The Gramineae: A Study of Cereal, Bamboo and Grass in 1934.
Following World War II, Katherine Esau published, Plant Anatomy (1953), which became the definitive textbook on plant structure in North American universities and elsewhere, it was still in print as of 2006. She followed up with her Anatomy of seed plants in 1960.
Adnation in Angiosperms is the fusion of two or more whorls of a flower, e.g. stamens to petals". This is in contrast to connation, the fusion among a single whorl.Archegonium
An archegonium (pl: archegonia), from the ancient Greek ἀρχή ("beginning") and γόνος ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium. The archegonium has a long neck canal or venter and a swollen base. Archegonia are typically located on the surface of the plant thallus, although in the hornworts they are embedded.Caudex
A caudex (plural: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.In the strict sense of the term, meaning a stem, "caudex" is most often used with plants that have a different stem morphology from the typical angiosperm dicotyledon stem: examples of this include palms, ferns, and cycads.
The related term caudiciform, literally meaning stem-like, is sometimes used to mean pachycaul, thick-stemmed.Gametophyte
A gametophyte () is one of the two alternating phases in the life cycle of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis.Gland (botany)
In plants, a gland is defined functionally as a plant structure which secretes one or more products. This may be located on or near the plant surface and secrete externally, or be internal to the plant and secrete into a canal or reservoir. Examples include glandular hairs, nectaries, hydathodes, and the resin canals in Pinus.Integument
In biology, integument is the natural covering of an organism or an organ, such as its skin, husk, shell, or rind.It derives from integumentum, which is Latin for "a covering". In a transferred or figurative sense, it could mean a cloak or a disguise. In English "integument" is a fairly modern word, its origin having been traced back to the early seventeenth century. It can mean a material or layer with which anything is enclosed, clothed, or covered in the sense of "clad" or "coated", as with a skin or husk.Locule
A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus).
In angiosperms (flowering plants), the term locule usually refers to a chamber within an ovary (gynoecium or carpel) of the flower and fruits. Depending on the number of locules in the ovary, fruits can be classified as uni-locular (unilocular), 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 contain the ovules or seeds.
The term may also refer to chambers within anthers containing pollen.In Ascomycete fungi, locules are chambers within the hymenium in which the perithecia develop.Operculum (botany)
In botany, an operculum (the term's plural is opercula) is any of the many botanical structures various vascular plants, mosses, and fungi; each of these have been construed as functionally analogous to the caps, flaps, and lids produced by tool-making animals.
(Opercula appearing in vascular plants are sometimes described as bud caps.)
Examples of structures (each identified as an operculum) include:
A flap of the sporangium of a moss, covering the peristome (appendages) surrounding the mouth of a moss capsule
The cap of the ascus in certain ascomycetous fungi
A lid covering the aperture of a pollen grain
The bud cap covering the flowers Eucalyptus and Corymbia trees which fall off as they open
The covering of a pyxidium (fruit capsule, whose upper part falls off when the seeds are released) of a plant, such as the plantain
The flared leaflet that prevents a pitcher plant from accumulating rainwaterPeduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green, though some peduncles are more or less florally colored or neutral in color, having no particular pigmentation. In some species, peduncles are leafless, though others bear small leaves, or even cataphylls, at nodes; such leaves generally may be regarded as bracts. The peduncle is the inflorescence base without flowers. When an unbranched peduncle has no obvious nodes, rises directly from a bulb or stem, and especially if it rises apparently directly from the ground, it commonly is referred to as a scape.The acorns of the pedunculate oak are borne on a long peduncle, hence the name of the tree.Perianth
The perianth (perigonium, perigon or perigone) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals). The term perianth is derived from the Greek περί, peri, meaning around, and άνθος, anthos, meaning flower, while perigonium is derived from gonos, meaning seed, i.e. sexual organs.
In the mosses and liverworts (Marchantiophyta), the perianth is the sterile tubelike tissue that surrounds the female reproductive structure (or developing sporophyte).Peristome
Peristome (from the Greek peri, meaning 'around' or 'about', and stoma, 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes.Plant cell
Plant cells are eukaryotic cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells.Seta
In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms.Sorus
A sorus (pl. sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. This New Latin word is from Ancient Greek σωρός (sōrós 'stack, pile, heap').
In lichens and other fungi, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus.
In ferns, these form a yellowish or brownish mass on the edge or underside of a fertile frond. In some species, they are protected during development by a scale or film of tissue called the indusium, which forms an umbrella-like cover.
Sori occur on the sporophyte generation, the sporangia within producing haploid meiospores. As the sporongia mature, the indusium shrivels so that spore release is unimpeded. The sporangia then burst and release the spores.
The shape, arrangement, and location of the sori are often valuable clues in the identification of fern taxa. Sori may be circular or linear. They may be arranged in rows, either parallel or oblique to the costa, or randomly. Their location may be marginal or set away from the margin on the frond lamina. The presence or absence of indusium is also used to identify fern taxa.Sporangium
A sporangium (pl., sporangia) (modern Latin, from Greek σπόρος (sporos) ‘spore’ + ἀγγεῖον (angeion) ‘vessel’) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores.Spur (botany)
The botanical term “spur” is given to outgrowths of tissue on different plant organs. The most common usage of the term in botany refers to nectar spurs in flowers.
nectar spur (flower)
The stamen (plural stamina or stamens) is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium.Staminode
In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen. Staminodes are frequently inconspicuous and stamen-like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the corolla.
Sometimes, the staminodes are modified to produce nectar, as in the Witch Hazel (Hamamelis).Staminodes can be a critical characteristic for differentiating between species, for instance in the orchid genus Paphiopedilum, and among the penstemons.
In the case of Cannas, the petals are inconsequential and the staminodes are refined into eye-catching petal-like replacements.
A spectacular example of staminode is given by Couroupita guianensis, a tropical tree growing in South America also known as cannonball tree.Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described.
In the case of ferns, the stipe is only the petiole from the rootstock to the beginning of the leaf tissue, or lamina. The continuation of the structure within the lamina is then termed a rachis.
In flowering plants, the term is often used in reference to a stalk that sometimes supports a flower's ovary. In orchids, the stipe or caudicle is the stalk-like support of the pollinia. It is a non-viscid band or strap connecting the pollinia with the viscidium (the viscid part of the rostellum or beak).
A stipe is also a structure found in organisms that are studied by botanists but that are no longer classified as plants. It may be the stem-like part of the thallus of a mushroom or a seaweed, and is particularly common among brown algae such as kelp. The stipe of a kelp often contains a central region of cells that, like the phloem of vascular plants, serves to transport nutrients within the alga.
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