Palisade cells
A group of cells just beneath the epidermis of the leaf, which contain most of the chlorophyll in the leaf and are responsible for the photosynthesis.
Panicle
Compound raceme made of up smaller racemes. The flower groups closest to the base are the oldest whilst new groups of flowers are produced as the influrorescence continues to grow.
Parasite
Not only uses another plant to give it support but also takes water and food from the supporting plant causing it to weaken and in extreme cases die.
Pathogen
An organism that causes disease like bacteria, viruses, and less correctly, fungi.
Pedicel
The stalk of an individual flower
Peduncle
The main stem supporting an inflorescence of flowers. Each flower will be attached to the penduncle directly or by a short stalk or pedicel.
Perennial
Any plant that lives more than three years and does not die after flowering once. The term is generally applied only to herbaceous plants, which die back to the ground each year, as opposed to those with persistent, woody stems - though there is a variety of opinion published.
Perianth
A collective term for all the external parts of the flower including the calyx, or sepals, and the corolla, or petals.
Petal
Coloured leaf like structure that grows between the sepals and stamens. They tend to be brightly coloured to attract pollinators.
Petiole
Stalk that connects the leaf to the stem.
Phloem
Vascular tissues that carries the food made in the leaves to the rest of the plant
Phosphorus (P)
Phosphorous stimulates the growth of roots and helps the plant create buds and flowers. It will also improve overall plant vitality as well as increase the size and potential of the seeds. This is achieved by transferring energy from one part of the plant to another e.g. the main body and roots to the seeds as it dies. The presence of organic matter and plenty of natural soil organisms help increase the availability of phosphorus to the plant as does a neutral ph - around 6.5 to 6.8.
Photosynthesis
Process whereby a plant converts energy from the sun into a storable form of energy. It occurs in the chloroplasts that contain chlorophyll. Chlorophyll absorbs energy from the sun and in the presence of Carbon Dioxide and water converts it to sugar and Oxygen.
Phylodes
Flattened petioles that function as a leaf. The phylodes have less stomata and therefore less water is lost by transpiration. Many Acacias have phylodes instead of leaves.
Picotee
A pattern of flower petal colouration where the edges are of a contrasting color to the main part of the petal.
Pinch Out
The removal of a growing tip from a stem which causes any axillary shoots or buds of the stem to develop. This can be at the top of a stem e.g. in shrubs to encourage it to bush out or it could be sideshoots on tomatoes which when removed will encourage a taller, stronger and more productive main plant.
Pistil
The female part of the flower. It consists of three parts the Stigma- the pollen receptor ; the Ovary and the style that connects the Stigma to the Ovary
Pollination
The transfer of pollen from the anther to the stigma. This can be facilitated by animals, birds, humans, wind and water
Pollination - Cross
Cross Pollination is the transfer of pollen from the anther of one plant to the stigma of another plant of the same species
Potassium (K)
Potassium is important to improve the overall health and vigor of a plant. It helps make carbohydrates (sugars, which are the source of energy) and also helps provide disease resistance and regulate metabolic activities.
Prickles
Pointed outgrowth of epidermis, they are found randomly on stem and do not grow from the leaf axil. These can be seen on Roses
Proteiod Roots
These are seasonal specialist roots grown in many species in the Proteaceae family. The fine groups of roots develop during the autumn and winter to take advantage of the high levels of nutrients created by the decaying leaves and higher levels of rainfall. The roots last only a few months and then die.