Ovule

A cell within an ovary in which an egg is produced, in preparation for fertilisation.

  Pedicel

The stalk that attaches a single flower, of which there will be several or many in an inflorescence, to the main flower stem (the Peduncle).

  Peduncle

The main stem which holds and supports the inflorescence or that of a single flower, depending on the flower arrangement of a plant.

  Perianth

A collective term for the corolla and calyx, which protect the reproductive organs.

  Petal

An inner feature of a flower, often coloured, and which encloses the male and female reproductive parts of a flower. The collective term for the petals is Corolla.

  Phloem

The internal network of plant vessels which carries dissolved nutrients throughout the plant. Phloem tissue also has sieve cells, which are not present in Xylem tissue.

  Photoperiod

The length of time, in hours, that a plant is exposed to light during a 24-hour period, with the exposure time varying depending on the time of year. This can be influenced by the addition of artificial light to extend natural day length. Plants can be grouped into one of three categories of photoperiod: Long-day plant; Short-day plant; or, Day-neutral plant.

  Photoperiodism

The response of plants, especially the biological processes of growth, development and reproduction, to changes in light (and dark) levels during a 24-hour period, with different plants having differing and specific requirements. Plant flowering is initiated by the changes in light received, whilst the photoreceptor molecule within plants is called phytochrome. See Photoperiod.

  Photorespiration

The usage of carbohydrates in a plant, especially when the temperatures are high and also when light levels are high: Respiration rate exceeds the rate of photosynthesis. This only occurs in cool-season, C3, plants and reduces the overall efficiency of photosynthesis. Over saturating a grass sward with artificial lighting (exceeding what is called the light saturation point) within a stadium situation will typically result in the usage of carbohydrates. This will also typically result in weaker rooting.

  Photosynthesis

The most important process for all of life on Earth. Light is captured by the green pigment chlorophyll, which is located within the plant cell chloroplasts. Carbon dioxide, which enters the plant by its stomata, and Water, which initially enters the plant through its root, form a reaction with sunlight which has been captured by the chlorophyll to produce carbohydrates and Oxygen.