Plant Tropism

The direction a plant moves in response to an external stimulus. If the plant growth moves towards the stimulus this is called positive tropism, whilst if growth moves away from the stimulus it is called negative tropism. The ability of plants to grow towards or away from certain conditions, helps them to optimise resources for growth and development within the prevailing environment. There are numerous types of tropism, including: 1. Phototropism: growth moving in response to light, typically towards the light. Plants will bend towards light typically due to a build-up of auxins on the

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  Plumule

A feature of the embryo from which the first shoot develops from the plumular bud, which is located at the top of the mesocotyl.

  Pollen [2]

Small powdery grains produced within anthers and which are released upon splitting / opening of the anthers.

  Pre-germinate

The action of wetting grass seed, either in a moist environment or even initially from a short soak in a container of water. If soaked in water the grass seed would be kept in a hessian sack, or similar permeable material, so that when it is removed the water can readily drain out of the material. The wetted seed is also kept in a warm environment. This action helps to kick-start growth. Just prior to any root or leaf appearance the grass seed would be sown in the required location.

  Procumbent

Low growing and spreading along a surface.

  Procumbent Plant

A plant that grows relatively low, being prostrate and trailing, to the ground, without upturned stems. A good example of a turfgrass weed of this habit is Procumbent Pearlwort (Sagina procumbens). Many ground cover plants are also procumbent in habit, for example Cotoneaster dammeri.

  Radicle

The first root, often called the primary seminal root.

  Raunkiaer System

A plant classification system, named after a Danish scientist, which is based on the location of the plant growing point (called its perennating bud) to the soil surface. There are seven main categories, and grasses fall within what is termed the Hemicryptophyte category, with buds being at ground level.

  Receptacle

The often slightly bulbous feature of stem from which a flower organ arises.

  Residual Height

The height at which tillers are defoliated. This term is often used where grass swards are grazed, but as a comparison it would mean the same as cut height where the sward was mown.