|
annulus 2 pl. annuli |
|
STRUCTURE |
|
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. |
|
carina 2 pl. carinae |
= keel |
STRUCTURE |
|
Collectively, the two relatively small, connate or coherent, abaxial (lower) petals that form the keel-like portion of a papilionaceous corolla. |
|
ostiole |
|
STRUCTURE |
|
The distal aperture of a syconium (fig); in Ficus (Moraceae). |
|
pulvinus pl. pulvini |
|
STRUCTURE |
|
A short, cushion-like swelling at the junction of stem and leaf or of inflorescence axis and branch. |
|
trophophyll |
= sterile frond |
STRUCTURE |
|
A frond that does not bear sporangia; in Polypodiophyta. See also fertile frond. |
|
viscidium pl. viscidia |
|
STRUCTURE |
|
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. |
|
mesocarp |
|
STRUCTURE |
|
The middle tissue layer of the pericarp of a fruit. |
|
ochrea |
|
STRUCTURE |
|
See ocrea. |
|
perigynium 1 pl. perigynia |
|
STRUCTURE |
|
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. |
|
crozier |
= fiddlehead |
STRUCTURE |
|
A circinate leaf (frond) prior to full expansion, while still wholly or distally coiled; esp. in Polypodiophyta. |
|
funicle |
= funiculus; < stalk |
STRUCTURE |
|
A stalk that attaches an ovule to a placenta of the ovary wall. |
|
spore |
|
STRUCTURE |
|
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. |
|
velum pl. vela |
|
STRUCTURE |
|
A membranous adaxial flap or fold of vegetative tissue wholly or partly covering the sporangial cavity of a sporophyll; in Isoëtaceae. |
|
aerial root |
> climbing root |
STRUCTURE |
|
A root, adventitious or not, that originates and functions entirely above ground during the normal life cycle of the plant. |
|
strobilus pl. strobili |
= cone; > female cone, macrostrobilus (not recommended), male cone, megastrobilus, microstrobilus |
STRUCTURE |
|
A compound or complex reproductive structure consisting of a central axis bearing congested sporophylls and sometimes other lateral members (e.g., bracts) that are sterile. |
|
inflorescence 2 |
|
STRUCTURE |
|
The basic architectural unit of the flower-producing portion of a plant; comprising one or more flowers, their associated supporting axes (peduncles, main axes, branches and pedicels), if any, and the appendages thereto (bracts, bractlets or bracteoles or prophylls, involucres, involucels, and glumes), if any; delimited by the insertion or gradation of a single peduncle, peduncle cluster, pedicel, pedicel cluster, or sessile flower, as the case may be, directly upon or into some proximal vegetative structure not of one of these types; depending upon the type(s) of flowers included, may be bisexual (all flowers bisexual), staminate (all flowers staminate), pistillate (all flowers pistillate), sterile (all flowers sterile), or mixed (two or more types of flowers present); most appropriately described using nominative terms. |
|
tetrad |
|
STRUCTURE |
|
A group of four pollen grains originating from a single pollen mother cell. |
|
appendage |
|
STRUCTURE |
|
Any subordinate structure ontogenetically derived from and associated with a given organ or part. |
|
needle |
< leaf, macrophyll (not recommended), megaphyll |
STRUCTURE |
|
A relatively stiff, compressed-acerose leaf; in Pinophyta. |
|
twig |
|
STRUCTURE |
|
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. |
|
wood |
= xylem |
STRUCTURE |
|
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. |
|
beak 1 |
= rostrum |
STRUCTURE |
|
A relatively long, tapering, more or less rigid and pointed enation or termination. |
|
axis pl. axes |
|
STRUCTURE |
|
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. |
|
mesochilium |
|
STRUCTURE |
|
The central portion of a labellum (lip) that has distinct proximal, distal, and central parts; in Orchidaceae. See also epichilium, hypochilium. |
|
ocrea pl. ocreae var. ochrea |
|
STRUCTURE |
|
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. |
