sapwood |
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STRUCTURE |
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That portion of the wood (xylem) of a stem or root whose cells are still living and functional; concentric about the heartwood once the latter has begun to form. |
hypogynium pl. hypogynia |
= gynophore; < stalk, stipe (broad sense, not recommended) |
STRUCTURE |
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The basal portion of an ovary when constricted and stalk-like above the level of perianth insertion, bearing the main body of the pistil at its summit; in Cyperaceae. |
prickle |
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STRUCTURE |
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Any unvascularized spine-like enation originating in the epidermis, cortex, or mesophyll of any shoot part. See also spine, thorn. |
trophophyll |
= sterile frond |
STRUCTURE |
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A frond that does not bear sporangia; in Polypodiophyta. See also fertile frond. |
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. |
mesocarp |
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STRUCTURE |
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The middle tissue layer of the pericarp of a fruit. |
vasculature |
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STRUCTURE |
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The vascular strands of all orders (veins and veinlets) in a particular part or organ, regarded collectively; consisting of conducting tissues (xylem, phloem) and associated supporting and enclosing tissues (e.g., sclerenchyma, collenchyma). |
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. |
torus 1 pl. tori |
= receptacle |
STRUCTURE |
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The relatively short, simple, axial structure surmounting a pedicel and basal to the flower, usually broader than the pedicel. |
embryo |
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STRUCTURE |
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The rudimentary spermatophyte contained within a viable seed. |
neck (archegonial) |
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STRUCTURE |
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The distal narrowed portion of an archegonium above its bulbous base. |
cladode |
= cladophyll, phylloclade |
STRUCTURE |
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A stem segment that functions as a leaf; often more or less compressed. |
operculum pl. opercula |
= lid |
STRUCTURE |
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A distal, cover-like portion of a structure whose main body is otherwise closed, transversely discontinuous with the main body around most of the circumference, or becoming partially or wholly separate by transverse dehiscence; as of an ascidium (pitcher), pollen grain, pyxis, or sporangium (spore case). |
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. |
seta 1 pl. setae |
= arista, awn, bristle |
STRUCTURE |
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A slender, more or less straight and stiff, fine-pointed, terminal or subterminal appendage or prolongation, sometimes a continuation of the bearing structure's central primary vein, as on a glume, lemma, or palea in Poaceae (Gramineae). |
dyad |
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STRUCTURE |
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A pair of coherent pollen grains shed as a unit. |
pneumatophore |
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STRUCTURE |
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A structurally and functionally specialized root serving as an aboveground aerating organ; found in some woody taxa of wet habitats, notably some mangroves. |
appendage |
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STRUCTURE |
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Any subordinate structure ontogenetically derived from and associated with a given organ or part. |
bulb |
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STRUCTURE |
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A thickened underground perennating structure consisting of a stem with numerous closely proximate nodes bearing many tightly imbricate, thickened, often fleshy, foliaceous organs containing large amounts of stored food, usually in the form of starch; the whole usually enveloped and protected by imbricated scarious or fibrous foliaceous organs. |
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. |
sorus pl. sori |
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STRUCTURE |
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A cluster of sporangia borne upon a fertile frond, usually on its abaxial surface; often covered during maturation by a protective membrane, the indusium, that is an outgrowth from the epidermis; in Polypodiophyta. |
crozier |
= fiddlehead |
STRUCTURE |
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A circinate leaf (frond) prior to full expansion, while still wholly or distally coiled; esp. in Polypodiophyta. |
pith |
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STRUCTURE |
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The central ground tissue of a stem or, when present, of a root, consisting of thin-walled parenchyma cells; distinct and more or less soft and spongy relative to the other tissues of the axis; sometimes partly or wholly degenerating after secondary growth has begun. |
torus 2 pl. tori |
= receptacle |
STRUCTURE |
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The short, expanded, compound axial structure surmounting a peduncle and basal to two or more flowers, or to the florets of a capitulum (head) in Asteraceae (Compositae), where it may bear paleae (receptacular bracts), scales, bristles, trichomes, or subulate enations, and may be smooth or variously pitted (alveolate, foveolate). |
coleorhiza |
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STRUCTURE |
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A sheath-like structure enclosing the radicle (embryonic root) in an embryo; esp. in Poaceae (Gramineae). |