Phenotype A group of individuals similar in appearance but not in genetical constitution

Phenotypic variation Variation produced by changes in environment.

Phloem The part of a vascular bundle consisting of sieve tubes, their companion cells, and adjacent parenchyma; the portion of the vascular bundle which is largely concerned in the transportation of food material; the inner part of the bark of a tree; the bast portion of a vascular bundle

Phosphate General term used to describe phosphorus-containing derivatives of phosphoric acid (H3PO4). The chemical containing the phosphate group (PO4-3) can be either organic or inorganic and either particulate or dissolved. Phosphates constitute and important plant nutrient

Photorespiration A process that occurs in the chloroplast and uses oxygen. Ribulose 1,5_ biphosphate is converted to phosphoglycolate and then glycolate. The glycolate is then shipped to the peroxisome and the mitochondria, where carbon dioxide is released. It is considered a wasteful process because it uses oxygen and releases carbon dioxide.

Photosynthesis The process of constructive metabolism in the green cells of a plant by which carbohydrates are formed in the presence of sunlight from carbon dioxide and water in the air with chlorophyll acting as an energy transformer.

Photosynthesis takes place in two phases:
First Phase:
6H2O + 6CO2------C6H12O6 + 6O2
Water + Carbon dioxide = Glucose + Oxygen
Second Phase:
n(C6H12O6)------- n(C6H10O5) + n(H2O)
Several glucose molecules together = Starch + Several Water molecules
First two inorganic substances, water (which plants absorb from the soil) and carbon dioxide (a gas which is absorbed from the atmosphere), plants produce first glucose and then starch, two organic substances that are part of living things. From the glucose, the mineral nitrogen, and other soil elements, vegetables produce all substances that form them through a complex series of chemical reactions.
Photosynthesis - a formidable chemical reaction - is possible only due to chlorophyll, a green pigment, which is found in green plants and acts as the catalysis for the reaction
Photosynthesis is the chemical basis of life on earth and though it seems quite simple, it has never been reproduced in a laboratory by any means. Through photosynthesis simple elements become complex: inorganic substances become organic substances. In other words, dead elements --from the soil and the atmosphere-- are transformed into living compounds---vegetables


phyllotaxy The pattern of leaf emergence of a plant. The arrangement of leaves on a stem is determined by the pattern of cell division and differentiation at the meristem and has a profound effect on the position of leaves, relative to one another. Phyllotaxy is usually constant and often diagnostic for any one species of plant. In sugarbeet, for example, all leaves emerge from the crown in an alternate pattern and are arranged in a 5/13 phyllotaxy. A 5/13 arrangement means that the leaves emerge from 13 vertical ranks around the crown and there are five turns around the crown before another leaf emerges in the same vertical rank.

Pinna A leaflet or a branch of a pinnately compound leaf.

Pinnate With leaflets or veins on each side of a common stem or vein in a feather-like arrangement.

pith Soft tissue with texture of sponge in the middle of the stem of many plants;

Plumule The embryonic shoot or bud in the seed located between the cotyledons which develops into the stem and leaves of the plant.

Pneumatophore An aerial structure which grows vertically upward from roots embedded in mud, composed of spongy tissue (aerenchyma), presumed to function as respiratory organs, as the knees of the bald cypress; the air bladder of water plants.

(my brain is turning to mush need bud fast)

Pollen The dusty or sticky material produced in the stamens of flowers. It is composed of microspores each of which contains two male nuclei and upon contact with a suitable stigma fertilizes the ovules to produce seed.

Pollination The transfer of pollen from anther to stigma.

Polymerase chain reaction (PCR). A method for enzymatically amplifying a DNA sequence in large amounts using a heat-stable polymerase and suitable primers to direct the amplification of the desired region of DNA. (wtf-karmaxul)

Primary root The root formed by an extension of the radicle of the embryo.

Primordial leaf The first leaf to succeed the cotyledons.

Primordium The earliest development of any structure or organ. A rudiment, an Anlage.

progeny The subsequent generation following a mating or crossing of parents; offspring.

Prokaryote A bacterial cell lacking a true nucleus; its DNA is usually in one long strand

Protein A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene coding for the protein. Proteins are required for the structure, function, and regulation of cells, tissues, and organs, and each protein has unique functions. Examples are hormones, enzymes, and antibodies.
A complex compound of oxygen, hydrogen, carbon, and nitrogen with traces of other elements; and albuminous substance which is an essential constituent of the living cell for food and growth.

Rachis 1. The main flower stem to which the outer parts are attached. 2. The axis of a compound leaf, spike, or raceme. 3. The main ribs of a frond.

Recalcitrant Marked by stubborn resistance to and defiance e.g. plants that are difficult to regenerate or propagate and seeds that are difficult to germinate.

Recombination frequency The frequency at which crossing over occurs between two chromosomal loci; the probability that two loci will become unlinked during meiosis.

Relative humidity (rh) The ratio of the amount of moisture or water vapour (vapour pressure) in the air (the humidity) to the total moisture that the air could hold at that temperature, i.e. saturated with water vapour (saturation vapour pressure), is the relative humidity. It is usually expressed as a percentage and abbreviated to rh. Air saturated with water vapour has a relative humidity of 100% and when only half saturated the rh is 50%. In UK experience, an rh of 69 to 70% is satisfactory for cold smoking

Rhizosphere The surface and immediate neighborhood of a root which provides a specialized environment for microorganisms. The term is also used to define the microflora that lives in this region.

Rhizosphere The region in the soil surrounding the root system of a plant which is affected by its excretions

Ribonucleic acid A chemical found in the nucleus and cytoplasm of cells; it plays an important role in protein synthesis and other chemical activities of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.

Root hair A tubular outgrowth from the epidermis of a young root which serves to absorb water and mineral salts from the soil. It arises above the root cap and growing point, and its cavity is continuous with the cell from which the root hair has developed.

Saprophyte A plant which lives upon dead animal or vegetable matter.

Sclerenchyma Rigid or strengthening tissue composed of thick-walled cells often having the shape of fibers, stone cells in tissue, hard tissue, mechanical supporting tissue.

Secondary root A root branching from other roots or growing from stems.

Selfed Fertilized by its own pollen, self-pollinated.

Selfing The pollination of a stigma with pollen from the anthers of the same flower or plant.

Sessile Without a stalk, sitting directly on the base.

Silica The mineral of which quartz, sand, flint, etc., are composed and which occurs in many rough (to the touch) plants.

Somatic embryogenesis Embryos are produced either from somatic cells of explants (direct embryogenesis) or by induction on callus formed by explants (indirect embryogenesis). a.k.a. asexual embryogenesis.

Spicule A small pointed appendage somewhat soft and fleshy, the point of the basidium in fungi, a sterigma, a diminutive spike or prickle.

Sporophore A mycelial structure which bears a spore, a spore-bearing branch or organ, a fruit body, the reproductive body in fleshy fungi.

Stigma The tip of a pistil which is receptive to the pollen grains and upon which they germinate.

Stoma An opening surrounded by guard cells which opens into internal air cavities, the breathing apparatus in the epidermis of leaves. Stomata are breathing pores in the epidermis of leaves or stems