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palea - n. (L. palea, chaff) the upper, and
usually shorter and thinner, of two
membranous bracts enclosing the flower in
grasses.
palmate - a. (L. palma, palm) leaves divided into lobes arising from a common center. pandurate - a. (L. pandura, a bandore) shaped somewhat like a violin, as some leaves. panicle - n. (L. panicula, a tuft of plants) a branched racemose inflorescence often applied more widely to any branched inflorescence. paniculate - a., panicled; arranged or growing in panicles. papilla - n. (L. papilla, nipple) a glandular hair with one secreting cell above the epidermis level. papillose - a. (L. papilla, nipple) descriptive of a surface beset with short, blunt, rounded, or cylindric projections. parenchyma - n. (Gr. para, besides; enchyma, infusion) plant tissue, generally soft and of thin-walled, relatively undifferentiated cells which may vary in structure and function. parietal - a. (L. paries, wall) when the placenta is attached to the wall of the ovary. peat - n. (ME. pete, fr. ML. peta, perh. of Celt. origin; akin to W. peth, thing - more at piece) a piece of turf cut for use as a fuel; a mass of partially carbonized plant tissue formed by partial decomposition in water of various plants and esp. of mosses of the genus Sphagnum, widely found in many parts of the world, varying in consistency from a turf to a slime used as a fertilizer, as stable litter, as a fuel, and for making charcoal. pectinate - a. (L. pecten, comb) comb-like. pedicel - n. (L. pedicellus, foot) the stalk of a flower in an inflorescence. peduncle - n. (LL. pedunculus, small foot) the stalk of a flower borne singly or the stalk of an inflorescence. peltate - a. (Gr. pelta, target) shield-shaped, leaves that are shaped like a shield and attached to the stem at the center or by some point distinctly within the margin, and having the petiole inserted into the undersurface of the lamina not far from the center. penicullate - a. (L. penicillus, a pencil or small brush) having the form of a pencil. perennation - n. (L. perennis, perennial) survival of a plant for a number of years. To live over from season to season. perennial - a. (L. perennis, through; annus, a year) a plant that grows for 3 or more years and usually flowers each year. perfect flower - a flower with both essential and accessory organs. perfoliate - a. (L. per, through; folium, a leaf) said of opposite or whorled leaves or bracts that are united into a collarlike structure around the stem that bears them. perianth - n. (Gr. peri, around; anthos, flower) the outer whorl of floral leaves of a flower, when not clearly divided into calyx and corolla; collectively, the calyx and corolla, or either one if one is absent. perigynium - n. (Gr. peri, around; gyne, female) fruit investing utricle of the sedges, Carex. perigynous - a. (Gr. peri, around; gyne, female) growing in a ring around the pistil, as the stamens; having stamens, etc. growing in this way, said of a flower. pericarp - n. (Gr. peri, around; karpos, fruit) the fruit wall which has developed from the ovary wall; sometimes used for any fruit covering. persistent - a. (L. persistere, to persist) remaining attached after the normal function has been completed. petal - n. (Gr. petalon, leaf) any of the component parts, or leaves, of a corolla; the unit of structure of the corolla. petaloid - a. (Gr. petalon, leaf; eidos, form) like a petal. petiolate - a. (L. petiolus, small foot) growing on, or provided with, a petiole. petiole - a. (L. petiolus, small foot) the slender stalk or stem of a leaf, also called a leaf stalk. phenotype - n. (Gr. phainein, to appear; typos, image) the characters of an organism due to the interaction of genotype and environment, a group of individuals exhibiting the same phenotypic characters. The detectable expression of the interaction of genotype and environment constituting the visible characters of an organism. phenotypic - a., a set of characters arising from reaction to environmental stimulus. phloem - n. (Gr. phloios, inner bark) the tissue involved in the transport of carbohydrates and food materials in a vascular plant, being composed of sieve elements, parenchyma cells and sometimes also of fibers and sclereids. phyllode - n. (Gr. phyllon, leaf; eidos, form) a winged petiole with flattened surfaces placed laterally to the stem and functioning as a leaf. phylogeny - n. (Gr. phyle, tribe; E. genesis) the racial history or evolutionary development of any plant or animal species. phyllotaxy - n. (L. phyllo-, and Gr. taxis, arrangement) the arrangement of the leaves on the stem. The three common positions are alternate, opposite, and verticillate. pileus - n. (L. pileus, cap) umbrella-shaped structure of mushrooms or toadstools. pilose - a. (L. pilosus, hairy) hairy; pubescence comprised of scattered long, slender, soft hairs. pinna - n. (L. pinna, feather) a leaflet or a primary division of a compound leaf. pl. pinnas or pinnae. pinnate - a. (L. pinnatus, feathered) divided in a feathery manner; with lateral processes of a compound leaf, having leaflets on each side of an axis or midrib. pinnule (also pinule) - n. (NL. pinnula, fr. L., small feather, small fin) a secondary pinna, one of the ultimate divisions of a bipinnate or twice-pinnate leaf. pistil - n. (L. pistillum, pestle) the unit of female function of a flower, may be comprised of a single carpel or two or more carpels united. pistillate - n., said of a flower bearing a pistil or pistils but not stamens, may refer also to a plant having only pistillate flowers. pith - n. (AS. pitha, pith) the soft, spongy tissue, consisting of cellular tissue, in the center of certain plant stems. placenta - a. (L. placenta, flat cake) the part of the ovary from which the ovules arise. It generally occupies the whole or a portion of an angle of a cell. placentation - n., the manner in which the placenta is arranged in the ovary. plano-convex - flat on one side and convex on the other. plant - n. (L. planta, plant) any of a kingdom (Plantae) of living beings typically lacking locomotive movement or obvious sensory organs, generally making its own food, possessing cell walls, and unlimited growth. plantlet - n., a little plant. plicate - a. (L. plicatus, to fold) folded into plaits, usually lengthwise; arranged in pleats, as a fan. plumose - a. (L. plumosus, feather) with hairlike branches, feathery. pocosin - n. (Algonquian) a bog that has formed in a shallow, undrained depression, the surrounding land being somewhat elevated, the vegetation predominantly evergreen shrubs or small trees. Pocosins vary greatly in size. pollen - n. (L. pollen, pollis, fine flour) the male or fertilizing element of seed plants, consisting of fine yellowish powder formed within the anther of the stamen. pollinium - n., a mass of coherent pollen characteristic of orchids and milkweeds. polygamo-dioecious - polygamous but chiefly dioecious. polygamo-monoecious - polygamous but chiefly monoecious. polygamous - a. (Gr. polys, much or many; gamos, marriage) having bisexual, pistillate, and staminate flowers on the same individual plant. polymorphic - a. (Gr. polys, many; morphe, shape) having, assuming, or occurring in various forms, characters, or styles. polypetalous - a. (Gr. polys, many; petalon, a petal) with many separate petals. pond - n. (form of pound, enclosure) a body of standing water smaller than a lake, often artifically formed. prickle - n. (ME. prikle, prikel, fr. OE. prickle, pricel; a kin to MD. prikel, prickle) a sharp pointed emergence arising from the epidermis or bark of a plant. primary production - the quantity of new organic matter created by photosynthesis. procumbent - a. (L. pro, forward; cubare, to lie down) trailing or lying flat but not rooting. production - n. (L. producere, to produce) the weight of new organic material formed over a period of time, plus any losses during that time period. Losses may be due to respiration, excretion, secretion, injury, death, or grazing. productivity - n., amount of production over a given period of time. Expressed as a rate such as g/m2 per day, kg/ha per year, etc. proliferous - a. (L. proles, prolis, offspring; ferre, to bear) bearing supplementary structures such as buds or flowers, either in an abnormal manner or in a manner that is normal but from adventitious tissue. propagulum or propagule - n. (L. propages, layer of a plant) a runner or sucker used in the asexual propagation of plants. pl. propagula or propagules. prostrate - a. (L. prostratus, pp. of prosternere, to lay flat) growing on the ground, trailing. protogyny - n. (Gr. proteros, fore; gyne, female) development of the female organs before the appearance of the corresponding male products - thus inhibiting self-fertilization. pseudolamina - n. (Gr. pseudes, false; L. lamina, plate) the extended apical portion of a phyllode. pseudovivipary - n. (Gr. pseudes, false; L. vivus, alive; parere, to produce) a condition where vegetative propagules replace some or all of the normal sexual flowers in the inflorescence. Pteridophyte - n. (Gr. pteris, fern; phyton, plant) a major division of the plant kingdom, having clear alternation of generations with a dominant vascular sporophyte initially dependent upon the gametophyte which is very reduced. puberulent - a. (L. pubes, adult) covered with fine, short, and nearly imperceptable down; minutely pubescent, the hairs soft, straight, erect, but scarcely visible to the unaided eye. pubescent - a. (L. pubescere, to become mature) a general term for hairiness; covered with soft hair or down. punctate - a. (L. puntcum, point) dotted; with depressed dots scattered over the surface. pustulate hair - a. (L. pustulare, to blister) hair with an enlarged base. pyriform - a. (L. pyrum or pirum, a pear) pear-shaped. |