Glossary of Plant Anatomy

male archesporial cell [PO:0006014; plant anatomy term ]
An archesporial cell (PO:0030056) that is part of a microsporangium (PO:0025202) and divides to gives rise to a microsporocyte (PO:0020047).
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megagametophyte [PO:0025279; plant anatomy term ]
A whole plant in the gametophyte development stage (PO:0028003) that produces only plant egg cells (PO:0020094).
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megasporangiate strobilus [PO:0005032; plant anatomy term ]
A strobilus (PO:0025083) that bears only plant ovules (PO:0020003).
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megasporangium [PO:0025201; plant anatomy term ]
A sporangium in which megaspores are produced.
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megasporangium endothecium [PO:0025310; plant anatomy term ]
An endothecium that is part of a megasporangium wall.
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megasporangium exothecium [PO:0025312; plant anatomy term ]
An exothecium that is part of a megasporangium wall.
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megasporangium tapetum [PO:0025315; plant anatomy term ]
A tapetum (PO:0025313) that is part of a megasporangium wall (PO:0025308).
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megasporangium tapetum cell [PO:0025564; plant anatomy term ]
A tapetum cell (PO:0025543) that is part of a megasporangium tapetum (PO:0025315).
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megasporangium wall [PO:0025308; plant anatomy term ]
A sporangium wall that is part of a megasporangium.
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megaspore [PO:0020019; plant anatomy term ]
The larger, in general, of the two kinds of spores produced after meiosis in the life cycle of a heterosporous plant, and on germination giving rise to the female gametophyte (embryo sac).
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megasporocyte [PO:0000431; plant anatomy term ]
A sporocyte (PO:0006204) that produces four haploid (1n) megaspores (PO:0020019).
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megasporophyll [PO:0009027; plant anatomy term ]
A structure upon which (or in the axil of which) one or more megasporangia are borne; in flowering plants, a carpel.
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meristem L1 layer [PO:0009020; plant anatomy term ]
A portion of meristem tissue (PO:0009013) that is the outermost layer of a shoot apical meristem (PO:0020148) and gives rise to a shoot system epidermis (PO:0006035).
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meristem L2 layer [PO:0009021; plant anatomy term ]
A portion of meristem tissue (PO:0009013) directly beneath a meristem L1 layer (PO:0009020) in a shoot apical meristem (PO:0020148) which gives rise to ground tissue (PO:0025059).
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meristem L3 layer [PO:0009022; plant anatomy term ]
A portion of meristem tissue (PO:0009013) beneath a meristem L2 layer (PO:0009021) in a shoot apical meristem (PO:0020148) which gives rise to internal tissues of leaf and stem.
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meristematic apical cell [PO:0030007; plant anatomy term ]
A single meristematic cell (PO:0004010) at the tip of a plant structure where apical growth occurs.
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meristematic cell [PO:0004010; plant anatomy term ]
A native plant cell (PO:0025606) synthesizing protoplasm and producing new cells by division and with only a primary cell wall.
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mesarch protoxylem [PO:0025553; plant anatomy term ]
A portion of protoxylem (PO:0000272) tissue in which the maturation of primary xylem (PO:0005849) of the shoot system (PO:0009006) progresses both centripetally and centrifugally from the center.
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mesocarp [PO:0009087; plant anatomy term ]
A portion of plant tissue (PO:0009007) that is the middle layer of a pericarp (PO:0009084).
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mesocotyl [PO:0020037; plant anatomy term ]
A stem internode (PO:0020142) that is the part of a plant embryo axis (PO:0019018) or a seedling stem (PO:0009047) above the scutellum (PO:0020110) and below the coleoptile (PO:0020033).
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mesophyll [PO:0006070; plant anatomy term ]
The chloroplast-containing, photosynthetic parenchymatous tissue situated between the two epidermal layers of the leaf or leaf like organs.
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mesophyll cell [PO:0004006; plant anatomy term ]
A chlorenchyma cell that is part of a mesophyll.
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mestome sheath [PO:0006025; plant anatomy term ]
The inner endodermal sheath of a two layered bundle sheath. The cells are smaller in diameter compared to those in outer wall (starch sheath). The cell walls are thick and contain suberized lamellae. They are analogous to endodermis.
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metaphloem [PO:0006076; plant anatomy term ]
A portion of primary phloem (PO:0006075) tissue that has as parts companion cells (PO:0000071, in angiosperms) or albuminous cells (PO:0025412, in gymnosperms) associated with the sieve elements (PO:0025406) and that develops after the protophloem (PO:0006077).
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metaxylem [PO:0000372; plant anatomy term ]
A portion of primary xylem (PO:0005849) tissue that has as part one or more metaxylem tracheary elements (PO:0025576) embedded in parenchyma (PO:0005421) tissue and may contain xylem fiber cells (PO:0000274).
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metaxylem tracheary element [PO:0025576; plant anatomy term ]
A primary xylem tracheary element (PO:0025444) that may have helical, scalariform, reticulate and/or pitted secondary wall thickening.
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microgametophyte [PO:0025280; plant anatomy term ]
A whole plant (PO:0000003) in the gametophyte development stage (PO:0028003) that produces plant sperm cells (PO:0000084).
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microgametophyte vegetative cell [PO:0020099; plant anatomy term ]
A native plant cell (PO:0025606) that is the larger cell of a microgametophyte (PO:0025280) in seed plants. It does not divide further and develops into a pollen tube cell (PO:0025195).
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micropylar endosperm [PO:0000200; plant anatomy term ]
A portion of plant tissue that is the region of the endosperm closest to the micropyle of the seed.
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micropyle [PO:0020025; plant anatomy term ]
A plant anatomical space that is enclosed by and forms an opening in an integument at the apex of an ovule.
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microsporangiate strobilus [PO:0005031; plant anatomy term ]
A strobilus (PO:0025083) that bears only pollen (PO:0025281).
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microsporangium [PO:0025202; plant anatomy term ]
A sporangium (PO:0025094) in which microspores (PO:0020048) are produced.
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microsporangium endothecium [PO:0025309; plant anatomy term ]
A sporangium wall endothecium (PO:0030049) that is part of a microsporangium wall (PO:0025307).
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microsporangium exothecium [PO:0025311; plant anatomy term ]
An exothecium that is part of a microsporangium wall.
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microsporangium tapetum [PO:0025314; plant anatomy term ]
An tapetum (PO:0025313) that is part of a microsporangium wall (PO:0025307).
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microsporangium tapetum cell [PO:0025544; plant anatomy term ]
A tapetum cell (PO:0025543) that is part of a microsporangium tapetum (PO:0025314).
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microsporangium wall [PO:0025307; plant anatomy term ]
A sporangium wall (PO:0025306) that is part of a microsporangium (PO:0025202).
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microspore [PO:0020048; plant anatomy term ]
The smaller, in general, of the two kinds of spores produced after meiosis in the life cycle of a heterosporous plant, and on germination giving rise to the male gametophyte.
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microspore-derived cultured plant embryo [PO:0025305; plant anatomy term ]
A cultured somatic plant embryo that develops from isolated microspores.
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microsporocyte [PO:0020047; plant anatomy term ]
A sporocyte (PO:0006204) that produces four haploid (1n) microspores (PO:0020048).
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microsporophyll [PO:0009028; plant anatomy term ]
A structure on which one or more microsporangia are borne; in flowering plants, the stamen.
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middle layer of ovary wall [PO:0005025; plant anatomy term ]
A portion of tissue that is composed of one or more mesophyll layers. It may have a distinct subepidermal adaxial cell layer (as found in Arabidopsis).
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modified aleurone [PO:0008008; plant anatomy term ]
A morphologically distinct aleurone layer located adjacent to the nucellar projection.
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monarch protoxylem [PO:0025558; plant anatomy term ]
A portion of root exarch protoxylem (PO:0025555) tissue in which the primary xylem (PO:0005849) of the root system (PO:0025025) has only one protoxylem strand or pole, and differentiation progresses centripetally, with the oldest element (protoxylem) farthest from the center of the plant axis (PO:0025004).
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multi-tissue plant structure [PO:0025496; plant anatomy term ]
A plant structure (PO:0009011) that has as parts two or more portions of plant tissue (PO:0009007) of at least two different types and which through specific morphogenetic processes forms a single structural unit demarcated by primarily bona-fide boundaries from other structural units of different types.
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multicellular plant gametangium [PO:0025124; plant anatomy term ]
A plant organ (PO:0009008) that produces one or more gametes (PO:0025006) and participates in the gametophyte development stage (PO:0028003).
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multicellular trichome [PO:0025162; plant anatomy term ]
A portion of plant tissue (PO:0009007) that forms a non-sclerified outgrowth from the epidermis (PO:0005679).
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multicellular trichome apex [PO:0025551; plant anatomy term ]
A portion of plant tissue (PO:0009007) that is the apical most portion of a multicellular trichome (PO:0025162).
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multicellular trichome branch cell [PO:0025163; plant anatomy term ]
A trichome cell (PO:0008030) that forms a branch of a multicellular trichome (PO:0025162).
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multicellular trichome tip [PO:0025535; plant anatomy term ]
A portion of plant tissue (PO:0009007) that is the apical most portion of a multicellular trichome apex (PO:0025551).
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myrosin cell [PO:0000352; plant anatomy term ]
A cell containing glucosinolates ("mustard oil glucosides") and myrosinases, enzymes hydrolyzing the glucosinolates.
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