ligule 3 |
|
STRUCTURE |
|
A relatively small, attenuate, membranous, laminar enation from the adaxial surface of a leaf near its base; in Selaginella, Isoetes. |
bristle 1 |
= arista, awn, seta |
STRUCTURE |
|
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). |
pistillode |
= pistillodium |
STRUCTURE |
|
Any sterile structure deemed to represent a modified pistil, homology being inferred on the basis of structural similarity, ontogeny, and/or position; sometimes nectariferous, sometimes connate with others or adnate to other floral structures. |
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. |
stomatal apparatus |
= stomate, stoma (broad sense) |
STRUCTURE |
|
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. |
blade |
= lamina |
STRUCTURE |
|
The expanded, more or less planate, distal portion, when present, of a leaf, leaflet or bract. |
sawtooth |
|
STRUCTURE |
|
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. |
flagellum pl. flagella |
|
STRUCTURE |
|
A very slender whip-like structure that extends from the main body of an antherozoid and, by active undulation, propels the cell through a liquid medium. |
raphides sing. raphis |
|
STRUCTURE |
|
Needle-like crystals of calcium oxalate contained within the cells of some plants; esp. in Araceae. |
vein |
= nerve; > costa, midnerve, midrib, midvein, rib |
STRUCTURE |
|
A strand belonging to any except the ultimate (least in diameter) order of vasculature in a leaf or other foliaceous structure. See also lateral vein, primary vein, secondary vein, tertiary vein, veinlet. |
fertile frond |
< spore leaf, sporophyll |
STRUCTURE |
|
A frond that bears sporangia; in Polypodiophyta. See also sterile frond (trophophyll). |
megasporangium pl. megasporangia |
= macrosporangium (not recommended) |
STRUCTURE |
|
A sporangium that produces megaspores. |
squamella 3 pl. squamellae |
= lodicule, squamule |
STRUCTURE |
|
One of two or three small, scale-like structures inserted at the base of the androecium, distal to the palea, in most grass (Poaceae) flowers; often regarded as a vestigial branch or perianth member. |
pappus pl. pappi |
|
STRUCTURE |
|
A set of one or more awns (aristae, bristles, setae) or scales at the summit of an inferior ovary just beneath or outside the free portion of the corolla; persisting in the fruit (cypsela) and often aiding wind or animal dispersal; in Asteraceae (Compositae). Considered by some to be an evolutionarily modified upper calyx portion, the lower portion having been incorporated into the floral tube casing adnate to the ovary wall; considered by others to be an outgrowth from the ovary wall. |
hydathode |
|
STRUCTURE |
|
A multicellular, anatomically distinctive structure located within a leaf at its periphery, its cells surrounding a central canal that opens to the exterior, through which water is actively discharged under humid conditions that impede the rate of transpiration; this liquid discharge is termed guttation. |
barb 1 |
|
STRUCTURE |
|
Any relatively short, stiff, sharp, acutely inserted or bent, antrorse or retrorse, terminal or lateral appendage. |
ligule 4 |
|
STRUCTURE |
|
The distal, relatively flat portion of the zygomorphic corolla of a ligulate floret, terminating in 5 teeth or lobes; in Asteraceae (Compositae). |
bristle 2 |
= seta; > glochid, glochidium; < trichome |
STRUCTURE |
|
A trichome that is elongate, more or less straight, terete, fine-pointed, and stiff. |
pistillodium pl. pistillodia |
= pistillode |
STRUCTURE |
|
Any sterile structure deemed to represent a modified pistil, homology being inferred on the basis of structural similarity, ontogeny, and/or position; sometimes nectariferous, sometimes connate with others or adnate to other floral structures. |
lamella pl. lamellae |
|
STRUCTURE |
|
A thin layer of tissue that forms a plate within tissue of lesser density or between areas of empty space. |
coleorhiza |
|
STRUCTURE |
|
A sheath-like structure enclosing the radicle (embryonic root) in an embryo; esp. in Poaceae (Gramineae). |
keel 1 |
= carina |
STRUCTURE |
|
An elongate, median longitudinal ridge that is basically triangular in transverse section and resembles the keel of a boat; esp. in leaf blades and sheaths, glumes, lemmata, paleae, sepals, petals. |
flange |
|
STRUCTURE |
|
A relatively broad, circumferential rim or ridge that protrudes laterally. |
ray 1 |
< primary axis |
STRUCTURE |
|
A first-order axis within a compound umbel. |
costa pl. costae |
= rib; > midnerve (not recommended), midrib, midvein; >< lateral vein |
STRUCTURE |
|
A primary vein of a laminar structure, having a longitudinal course, either medial or lateral, often prominent. See also secondary vein, tertiary vein, veinlet. |