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Lip
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The median petal of Orchidaceae which is usually highly modified and different from the two lateral petals, the lip of orchids often plays a crucial role in the plant's pollination; one of the two divisions of a bilabiate corolla, e.g., in the Lamiaceae. |
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Lodicule
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A small, colorless scale appressed to the ovary of most Poaceae that may represent a vestige of the perianth. |
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Longitudinal anther dehiscence
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Same as lateral anther dehiscence. |
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Lophate
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Referring to a type of pollen ornamentation in which the exine is raised in a network of ridges surrounding depressions. |
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Male flower
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Referring to unisexual flowers with functional stamens but without functional gynoecia (pistillodes may be present). Same as pistillate flower. |
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Marginal placentation
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A type of parietal placentation in which the ovules arise along the margins of the carpel. Compare with laminar placentation; see placentation. |
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Megagametophyte
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The female gametophyte of angiosperms (flowering plants). Same as embryo sac. |
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Mentum
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In some Orchidaceae, a lateral (sometimes nectariferous) projection from the base of the column formed by the fusion of the base of the column and the lateral sepals; common in Scaphyglottis. |
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Mesochile
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The central portion of a complex lip in Orchidaceae. |
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Microgametophyte
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See pollen. |
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Micropyle
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An opening in the integuments of the ovule through which the pollen tubes generally penetrate. |
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Monad
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A pollen grain that occurs singly. Compare with tetrad. |
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Monadelphous
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Referring to stamens united by their filaments into a single group. |
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Monochlamydeous
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Referring to a flower with a single whorl of perianth parts; same as a uniseriate perianth. Compare with heterochlamydeous. |
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Monocolpate
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A pollen grain with a single colpus. |
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Monosulcate pollen
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Referring to a pollen grain with one groove or furrow. |
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Monosymmetric flower
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A flower capable of being divided into only two equal parts (mirror images) by a line passing through the middle of a flower, i.e., other lines passing the middle of the flower will not give mirror images of one another; same as zygomorphic, bilaterally symmetrical, and irregular flowers and opposite of actinomorphic, monosymmetric, radially symmetrical, and regular flowers. This term can refer to other plant parts as well. |
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Monothecous
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Referring to an anther with a single theca. |
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Nectar
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A sugar solution of varied composition produced by nectaries within flowers to attract pollinators or by extrafloral nectaries to attract insects that protect the plant from predation. |
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Nectar guide
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Markings on a flower that apparently serve to guide pollinators to the nectar. Some are visible to humans, but others are apparent to humans only through ultraviolet photography. Same as honey guide, a term not recommended because bees, not plants, produce honey. |
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Nectar ring
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In some Passifloraceae, a low narrow ring situated below the operculum. |
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Nectar spur
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A tubular-like projection from the sepals or petals that produce and retain nectar as a reward for pollinators; in many orchids nectar spurs are hollow, tubular projections formed at the base of the lip which contain nectar rewards for pollinators. |
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Nectariferous disc
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A more or less fleshy and elevated part of the receptacle, situated between the perianth and the stamens or between the stamens and the gynoecium, which functions in the production of nectar. Also referred to simply as a disc. |
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Nectary
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A tissue or structure of flowers that produces nectar. |
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Nectary scale
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A appendage (bracteole-like) located between the flowers of some Capparidaceae upon which the nectary gland (= nectary) is located. |
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Non-resupinate
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Turned 180° in development; e.g., flowers of most orchids in which the lip originates in the uppermost position but twists in such a way that the labellum faces downward at anthesis. Some orchids do not twist, thus the labellum faces up at anthesis. |
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Nucellus
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The tissue that surrounds the megasporophyte or the embryo sac. It is located between the embryo sac and the integument or integuments. |
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Nuclear endosperm
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Endosperm development in which many nuclei develop before cell walls are formed. |
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Obdiplostemony (obdiplostemonous)
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With two series of stamens with twice the number of stamens as petals and those of the outer series inserted opposite the petals and those of the inner series inserted opposite the sepals. Obdiplostemony is sometimes very difficult to determine in flowers at anthesis but become apparent with microtome and SEM studies of bud development (Endress, 2010). |
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Obturators
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In the Styracaceae, outgrowths of the placental wall that partly cover the ovules. |
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Osmophore
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Tissue or a gland, usually associated with flowers, from which aromas emanate. |
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Ovariodisc
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In the Burseraceae, a single, parenchymatous structure representing the ontogenetic fusion of the nectary disc and the pistillode. |
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Ovary
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The part of the gynoecium (=pistil) containing the ovules. |
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Ovule
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The organ that after fertilization becomes the seed. The ovule in angiosperms contains the embryo sac with an egg cell, several other cell types, and is enclosed within the locule of the ovary. |
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Ovule anatropous
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Referring to a curved downward ovule in such a way that the micropyle is close to the funicular attachment. |
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Ovule campylotropous
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Referring to an ovule in which the axis is at an approximately right angle to its stalk (funicle). |
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Ovule orthotropous
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Referring to a straight ovule in which the micropyle is positioned in a straight line and opposite the funicular attachment; referring to a growth habit in which the growing apex is oriented vertically. |
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Ovules bitegmic
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An ovule with two integuments. |
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Ovules tenuinucellate
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The presence of no cells or a single cell layer between the megasporophyte and the epidermal cells in the early development of the megasporophyte. |
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Palate
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In the Lentibulariaceae and Scrophulariaceae, the space at the throat and limb of the corolla used by pollinating insects as a landing platform. |
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Palea
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The upper of the two bracts that enclose the floret in the Poaceae. Compare with lemma. |
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Papilionaceous corolla
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The zygomorphic corolla of most species of papilionoid legumes. |
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Papilionoid
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Referring to flowers similar to those of Fabaceae subfamily Papilionoideae; e.g., those of the Polygalaceae. |
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Pappus
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A modified calyx of hairs, scales, or bristles typical of many Asteraceae. |
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Parietal placentation
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A type of placentation found in compound, unilocular ovaries in which the ovules arise from placentae inserted on the wall of the locule near the sutures. |
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Pedicel (adj. = pedicellate)
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The stalk supporting some flowers. |
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Perfect flower
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Referring to a flower that possesses both male (staminate) and female (pistillate) organs. |
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Perianth
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The collective term for the calyx and the corolla, even when they are not differentiated (i.e., represented by tepals). |
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Pericarpel
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In the Cactaceae, the part of the receptacle fused to the ovary. |
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Perigon (perigoniate)
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A reduced perianth found in the flowers of some species of Araceae, Monimiaceae, and Siparunaceae. |
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