The term ‘deciduous’ is generally accepted to mean ‘to discard after useful purpose is finished’ hence the falling of leaves at the end of a growing season. This shedding of leaves takes place during late autumn in the UK and other temperate regions, for the plants effectively go into a dormant state during the winter.
In some tropical areas, leaf drop takes place in the heat of the dry seasons. In this case, there being no soil water, there is no purpose for the leaves, for they cannot function without the plant absorbing water from the soil or atmosphere.
A deciduous plant is normally a shrub or tree that lives for several years but sheds its foliage each autumn. ‘Garden perennial’ plants are rarely deciduous but either evergreen or herbaceous – the latter dying to ground level in the winter, but then emerging again the following spring.
Deciduous shrubs and trees are those with woody stems which remain throughout the winter and not die back to ground level each year. The fact that they are classed as deciduous is that they lose their foliage each autumn – sometimes with spectacular foliage colour change before the leaves drop. They retain their basic structure of stems and branches whether they have leaves or not.
Some shrubs - and trees -which are deciduous have a good period of interest in the winter by way of coloured stems and trunks - largely hidden when the shrub is in full leaf.
Image of Acer palmatum foliage just before deciduous leaf drop in autumn.
Annuals such as bedding plants are not classified as deciduous for they simply die at the end of the first year (There are exceptions). Simply losing their leaves at the end of the year – and hence end of their life – does not qualify them as being deciduous plants. They are annuals, biennials or tender perennials which die off in the winter.
Typical deciduous shrubs are