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annulus 2 pl. annuli |
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STRUCTURE |
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A row of protruding specialized sporangial wall cells that extends upward from the base of the sporangium and over its apex, thus forming an incomplete circumferential ring; esp. in Polypodiophyta. The inner and radial walls of the annular cells are markedly thickened and the structure functions as a spore-releasing and -disseminating mechanism as a result of differential stresses developed within the mature sporangial wall upon desiccation. |
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carina 2 pl. carinae |
= keel |
STRUCTURE |
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Collectively, the two relatively small, connate or coherent, abaxial (lower) petals that form the keel-like portion of a papilionaceous corolla. |
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ostiole |
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STRUCTURE |
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The distal aperture of a syconium (fig); in Ficus (Moraceae). |
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pulvinus pl. pulvini |
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STRUCTURE |
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A short, cushion-like swelling at the junction of stem and leaf or of inflorescence axis and branch. |
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trophophyll |
= sterile frond |
STRUCTURE |
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A frond that does not bear sporangia; in Polypodiophyta. See also fertile frond. |
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viscidium pl. viscidia |
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STRUCTURE |
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A small, viscid, glandular body of rostellar origin that becomes connected with a pollinium caudicle, either directly or through an intervening stipe, by which the pollinium attaches to a pollinating insect; in Orchidaceae. |
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ampulla pl. ampullae |
= bladder |
STRUCTURE |
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A small, membranous, hollow, flask-shaped, insectivorous structure borne on a submerged leaf; esp. in Lentibulariaceae. |
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division |
? lobe, segment |
STRUCTURE |
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Any generally convex, major peripheral protrusion or component sector that is delimited by concavities in the surface or margin and that is not proximally distinct from the remainder of the whole. |
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sporangium pl. sporangia |
= spore case |
STRUCTURE |
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A spore-producing organ; basically capsular, often supported by a slender stalk (sporangiophore), often operculate (lidded). In Bryophyta and Polypodiophyta, a distinct portion of the sporangial wall effects regular dehiscence at maturity. Sporangia or their equivalents are also present, but of little or no descriptive significance, in seed plants. |
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involucel |
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STRUCTURE |
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One or more closely proximate whorls of bractlets (bracteoles, prophylls) immediately subtending (below or outside) a subordinate portion of an inflorescence that is subtended as a whole by an involucre, the bractlets often leaf-like, sometimes petaloid. |
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velamen pl. velamina |
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STRUCTURE |
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A thin, often chartaceous (papery, papyraceous) or pergamentaceous (parchment-like), outermost tissue layer of an aerial root; esp. in Orchidaceae. |
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cilium 2 pl. cilia |
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STRUCTURE |
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A motile hair- or whip-like structure extending from the surface of a cell. |
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costa pl. costae |
= rib; > midnerve (not recommended), midrib, midvein; >< lateral vein |
STRUCTURE |
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A primary vein of a laminar structure, having a longitudinal course, either medial or lateral, often prominent. See also secondary vein, tertiary vein, veinlet. |
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spermatozoid |
= antherozoid; < sperm |
STRUCTURE |
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A motile male gamete, produced within an antheridium. |
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nectary |
< gland |
STRUCTURE |
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A multicellular, anatomically distinct structure that produces and exudes nectar. |
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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. |
