BBC Gardeners' World

Alkaline soil

Soil with a pH above 7 that produces a blue reaction when in contact with universal indicator solution (see pH). Alkaline soils are suitable for growing a wide range of plants, with the exception of those that are ericaceous or calcifuge (lime-hating).

Alpine

In gardening, this term is used for any plant that is native to alpine zones of the world. This zone is identified as being below the permanent snow line and above the tree line. Alpines have many adaptations to this environment, including deep roots, a low-growing habit and small foliage.

Alternate

Refers to the alternate arrangement of leaves, stems, buds or flowers on each side of the stem, rather than growing in pairs. See Opposite.

Androecium

Botanical term for the male part of a flower, which comprises one or more stamina. These feature the pollen-bearing anthers, which are usually borne on stalk-like filaments.

Annual

A term to describe a plant that completes its life cycle (germinating, growing, flowering, setting seed and dying) within a single growing season.

Anther

The pollen-bearing structure on the male part (stamen) of a flower. Each anther is composed of a pair of small capsule-like sacs or lobes, which split open to release pollen grains.

Anthracnose

A general term (also see Canker) covering a large number of plant diseases sharing similar symptoms, namely patches of dead tissue on leaves or stems. These are caused by a range of organisms, including fungi, bacteria, mycoplasmas and viruses.

Ants

Ants are eusocial insects that belong to the same order as wasps and bees.

Apex

1) The growing point at the tip of a stem or root.

2) Refers to the pointed tip of a leaf.

Aphid

Minute plant-feeding insects within the super family Aphidoidea. Commonly known as greenfly, blackfly or plant lice.