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tetrad |
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STRUCTURE |
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A group of four pollen grains originating from a single pollen mother cell. |
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appendage |
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STRUCTURE |
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Any subordinate structure ontogenetically derived from and associated with a given organ or part. |
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needle |
< leaf, macrophyll (not recommended), megaphyll |
STRUCTURE |
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A relatively stiff, compressed-acerose leaf; in Pinophyta. |
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twig |
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STRUCTURE |
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The terminal portion of an ultimate branch of a woody stem, representing the most recent increment of growth and bearing or having borne the current or most recent increment of leaves. See also branchlet. |
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wood |
= xylem |
STRUCTURE |
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The water-conducting and usually main supporting tissue of a plant or portion thereof, characterized by the presence of tracheary elements (tracheids and sometimes vessel elements); the lignified tissue of a plant or component structure, composed almost entirely of secondary tissue, i.e., that derived by secondary or lateral growth from a cambium in structures a season or more old. As commonly used, the term wood generally refers only to secondary xylem, which constitutes the bulk of a mature woody stem, but it properly refers also to primary xylem, wherever found. See also sapwood, heartwood. |
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beak 1 |
= rostrum |
STRUCTURE |
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A relatively long, tapering, more or less rigid and pointed enation or termination. |
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mesocarp |
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STRUCTURE |
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The middle tissue layer of the pericarp of a fruit. |
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ochrea |
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STRUCTURE |
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See ocrea. |
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perigynium 1 pl. perigynia |
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STRUCTURE |
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Two whorls of bracts, scales or setae immediately subtending the ovary, sometimes cupulate (cup-shaped) or ampulliform (flask-shaped, lageniform) and investing the fruit (achene); in Cyperaceae. |
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crozier |
= fiddlehead |
STRUCTURE |
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A circinate leaf (frond) prior to full expansion, while still wholly or distally coiled; esp. in Polypodiophyta. |
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funicle |
= funiculus; < stalk |
STRUCTURE |
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A stalk that attaches an ovule to a placenta of the ovary wall. |
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spore |
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STRUCTURE |
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A simple, usually unicellular, sometimes oligocellular propagule derived by meiotic division of a diploid (2n chromosomes) sporocyte within a sporangium, thus of haploid (n chromosomes) genetic constitution. A spore constitutes the first ontogenetic stage of a gametophytic generation and gives rise to a usually multicellular gametophyte upon germination. Though technically present in seed-bearing plants, by itself it is descriptively significant only in those taxa that do not produce seeds. |
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velum pl. vela |
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STRUCTURE |
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A membranous adaxial flap or fold of vegetative tissue wholly or partly covering the sporangial cavity of a sporophyll; in Isoëtaceae. |
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aerial root |
> climbing root |
STRUCTURE |
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A root, adventitious or not, that originates and functions entirely above ground during the normal life cycle of the plant. |
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sawtooth |
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STRUCTURE |
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One of a series of regularly spaced, angular, marginal convexities oriented at an acute angle to the generalized perimeter of a laminar structure. See also sawtoothlet, scallop (crena), scalloplet (crenule), tooth, toothlet. |
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stipe 1 |
< stalk |
STRUCTURE |
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A small, slender connection between a pollinium caudicle and a viscidium; in Orchidaceae. |
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beak 2 |
= rostrum |
STRUCTURE |
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The inner, horn-like segment of a coronal lobe; esp. in Asclepiadaceae. |
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ovary |
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STRUCTURE |
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The proximal portion of a pistil (either simple or compound) within which the ovules are borne; usually of somewhat greater diameter and/or volume than the remainder of the pistil. |
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axis pl. axes |
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STRUCTURE |
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Any unitary and longitudinally continuous structure that bears laterally the subordinate portion(s), if any, of a plant root or shoot or any subdivision thereof and that represents the main line of structural development and/or symmetry distal to its origin, irrespective of the particular ontogenetic growth pattern involved. See also primary axis. |
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mesochilium |
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STRUCTURE |
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The central portion of a labellum (lip) that has distinct proximal, distal, and central parts; in Orchidaceae. See also epichilium, hypochilium. |
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ocrea pl. ocreae var. ochrea |
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STRUCTURE |
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A tubular sheath that encircles a stem at a node, subtending a petiole; thought to have arisen evolutionarily by lateral fusion of two stipules; in Polygonaceae. |
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perigynium 2 pl. perigynia |
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STRUCTURE |
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A phyllary (involucral bract) or palea (pale, palet) that fully encloses a cypsela; in Asteraceae (Compositae). |
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spore body |
= sporocarp |
STRUCTURE |
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A multicellular structure that bears and more or less encloses several to (usually) many sporangia, the latter often aggregated into sori within it See also megasporocarp (macrosporocarp, not recommended), microsporocarp. |
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involucral bract |
= phyllary; < bract (broad sense) |
STRUCTURE |
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One of the bracts composing the involucre of a capitulum (head,); in Asteraceae (Compositae). |
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strophiole |
= caruncle |
STRUCTURE |
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An outgrowth from the seed coat (testa) around or near the hilum and micropyle, or from the raphe. |
