Ascospore

A fungal spore contained within an ascus.

  Ascus

A sack like structure which contains the spores (usually 8) for fungi in the phylum Ascomycota.

  Asexual Reproduction

The reproduction of a plant by vegetative means, without being produced from seed, and which commonly occurs in turfgrasses. A plant which has been reproduced asexually is genetically the same as the parent plant because there has been no new combination of female and male cells, which would occur in the pollination and then germination of a new seed (and this is called sexual reproduction).

  Atmospheric Fixation

The production of Nitrate (NO3) by the actions of lightning with Oxygen and Nitrogen.

  Atom

An atom is composed of one nucleus, which itself contains one or more positively charged pro-tons, and neutrons, which have no charge, and is surrounded by one or more negatively charged electrons.

  Atomic Number

The number of protons within the nucleus of its atom. The number of protons also give the atom its atomic number and uniquely identifies an element. For example, the atomic number of Carbon is 6, whilst for Nitrogen it is 7.

  Attribute

A single descriptive feature of something. For example, a performance standard might have a range of attributes, including name of the standard (sward or vegetation height); unit of measure (e.g. mm); value (as a parameter, e.g. 25, or 45 - 50); a qualifier to a value (indicating if the value is a range, maximum value, minimum value, greater than or equal to; less than or equal to, or a statement), and a quality grade (for example, 1 to 5, or Entry to Elite) where this is included as an attribute rather than an overarching category.

  Autoecious

The completion of a life cycle by an organism on a single host. Many rust fungi species are autoecious, being a parasite of the specific plant they are living on.

  Autotroph

An organism, especially plants and algae, that uses simple inorganic materials, such as carbon dioxide and other elements, along with energy from photosynthesis (or by chemosynthesis in some organisms where sunlight does not penetrate to where they reside) to create complex organic materials, such as carbohydrates. Autotrophs are called primary producers because they create their own food. Compare Heterotroph.

  Autotrophic

An organism which creates its own food source from the synthesis of simpler elements and materials. Green plants are autotrophic organisms.