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primary axis |
> ray |
STRUCTURE |
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A main or first-order axis within any specified, uniformly delimited structural context. |
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throat 1 |
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STRUCTURE |
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The far distal portion of a perianth, calyx, or corolla tube, or of a leaf sheath, surrounding the orifice of the tube or sheath, sometimes constricted relative to the diameter of the main body of the tube or sheath; except in disc florets of Asteraceae (Compositae). |
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ligule 2 |
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STRUCTURE |
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An adaxial, distal enation from a leaf sheath, especially in most grasses (Poaceae) and sedges (Cyperaceae); usually unitary and membranous, sometimes instead consisting of a row of ciliate processes. See also hastula. |
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macrophyll (not recommended) |
= leaf, megaphyll; > frond, needle |
STRUCTURE |
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A principal, vegetative shoot organ borne laterally from a stem node; its vascular tissues, if any, continuous with those of the stem; undergoing no significant secondary growth; usually more or less bilaterally symmetrical; comprising a distal, usually laminar blade and/or a proximal stalk (petiole) or sheath; usually a primary site of photosynthesis. |
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epidermal cell |
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STRUCTURE |
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Any of the unspecialized cells of an epidermis; i.e., any other than stomatal guard cells or cells directly associated with trichomes. While the latter specialized cells are also properly epidermal cells, they are treated separately for descriptive purposes and, for the sake of convenience, use of the general term is restricted to the unspecialized cells that constitute the bulk of an epidermis. |
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stomate |
= stomatal apparatus, stoma (broad sense) |
STRUCTURE |
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A localized functional epidermal unit consisting of a microscopic pore and two encircling specialized cells, the guard cells, which, through changes of turgor pressure in response to environmental conditions, regulate the size of the pore and thus the rates of transpiration and gas exchange through it; the whole surrounded or not by associated, cytologically distinctive epidermal cells, the subsidiary or accessory cells, which, when present, are regularly oriented in relation to it. |
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tendril |
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STRUCTURE |
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A slender stem branch, modified leaf, or portion of a leaf that twines about a supporting structure. |
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pale 2 |
= palea, palet |
STRUCTURE |
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The upper or distal of the (usually) two distinctive bracts immediately subtending the flower in a grass (Poaceae) spikelet. |
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husk |
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STRUCTURE |
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A more or less dry, hard or fibrous, simple or compound enclosure or outer layer of a seed, fruit or inflorescence. |
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tuberoid (root-stem) |
= dropper |
STRUCTURE |
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An axial outgrowth that descends from a bulb and eventually forms a new bulb; esp. in Orchidaceae. |
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culm |
< cane, stem |
STRUCTURE |
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A stem of a sedge (Cyperaceae) or grass (Poaceae), usually hollow. Use of this term or cane instead of stem is a matter of tradition and preference, not of descriptive precision or necessity. |
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pseudostem |
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STRUCTURE |
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A structure that resembles a stem but is not part of the axial system of a shoot, lacking anatomical differentiation into nodes and internodes. |
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squamella 1 pl. squamellae |
= squamule; < scale, trichome |
STRUCTURE |
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A diminutive squama (lepis). |
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vesicle |
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STRUCTURE |
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A small bladder-like part consisting of an enclosing wall or covering and an empty or fluid-filled interior, sometimes turgid; esp. in citrus fruits (hesperidia). |
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primary root |
> taproot |
STRUCTURE |
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The one, central root directly basal to a shoot, developing directly from the embryonic radicle; the first-formed root of a plant, being the only one truly central in nature (i.e., belonging to the original central axis of the plant). All other roots of a plant develop subsequently and are lateral in nature. The primary root may be permanently dominant, developing into a taproot; otherwise it may be transitory or become functionally subordinate, with secondary and/or adventitious roots becoming dominant. |
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seed |
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STRUCTURE |
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A mature or ripened ovule containing an embryonic sporophyte and a nutritive tissue (endosperm or perisperm) with stored food that sustains the initial growth of the embryo upon germination, except when such food reserve is stored instead in the cotyledon(s) of the embryo itself, these enclosed by one or two integuments (the testa), the whole serving as a propagule. A fertile seed (one containing a viable embryo) normally results from sexual fertilization of an egg by a sperm; however, fertile seeds are sometimes produced asexually by apomictic processes (e.g., parthenogenesis). |
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integument |
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STRUCTURE |
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A distinct layer of tissue that encloses and serves to protect the other tissues of an organ, especially a seed. |
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throat 2 |
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STRUCTURE |
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The fully connate portion of the limb of a disc floret, proximal to the lobes (distinct distal portions of the petals); in Asteraceae (Compositae). |
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ligule 3 |
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STRUCTURE |
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A relatively small, attenuate, membranous, laminar enation from the adaxial surface of a leaf near its base; in Selaginella, Isoetes. |
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areole 1 |
= areola |
STRUCTURE |
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Any distinctive surficial discontinuity of generally circular outline, whether concave, flush, or convex; when protuberant, sometimes bearing trichomes or spines, as in some Cactaceae. This term is used only when such entities are deemed structurally distinctive enough to merit description in their own rights, rather than as aspects of the surface. |
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bracteole 1 |
= bractlet; < bract |
STRUCTURE |
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A diminutive bract, or a bract that is smaller than others present. |
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node |
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STRUCTURE |
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One of the evident sectors of a stem that occur sequentially along its length and from which leaves (megaphylls) and lateral branches arise exogenously. The anatomy of nodes differs from, but is not abruptly distinct longitudinally from, that of the intervening sectors (internodes), with which it is smoothly confluent and from which is distinguished by the lateral transit and egress of vascular traces interconnecting the stem and the leaves and branches that it bears. |
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corniculum pl. cornicula |
= horn |
STRUCTURE |
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A straight or curved, slenderly conic or conoidal protrusion or terminal portion that resembles an animal horn. |
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pollen |
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STRUCTURE |
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Collectively, the spores or grains produced within the thecae of anthers, each containing a very small microgametophyte (or its evolutionary homologue); serving as disseminules from which microgametes are released after transport to a receptive micropylar pollen droplet (in Pinophyta) or stigma (in Magnoliophyta) by a variety of vectors, notably wind, water, insects, bats, and birds. |
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epidermis pl. epidermides, epidermises |
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STRUCTURE |
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The anatomically distinct, outermost, living tissue that encloses and protects the other tissues of a plant organ or part, usually overlaid by an exuded waxy cuticle; resulting from primary growth, disrupted and shed as a consequence of secondary growth if that occurs; consisting mainly of cells not further specialized, otherwise including various types of more specialized cells associated with trichomes and stomates. |
