Coastal plants are adapted to this harsh coastal environment in a variety of ways, but all are adapted to wind pruning, surviving some very strong winds. This should also be a consideration when growing in the home garden as some of the coastal species, if grown in a sheltered environment, will grow into much taller plants. A classic example is the Peppermint which on the face of the foredunes will be about 1m tall but in the lee of the dune, away from the wind, will grow into a tree up to 8m tall.
Other adaptations shown by these plants include:
- Hairy or scaly leaves. The hairs on the leaf surface reduce water loss through evaporation by retaining a humid environment on the leaf surface as some of the water vapour is trapped by the hairs. Some of the hairy leaved plants are white due to the dense cover of hairs e.g. the Native Rosemary, Olearia axillaris.
- Scaly leaves. Some plants have scales on their leaves and stems which also reduce the loss of water vapour from the plant. These are typically seen in the Atriplex species of the Salt Bush Family (Chenopodiaceae).
- Leaves reduced in size. If the leaf is small there is a smaller surface for water loss e.g. the Rottnest Teatree, Melaleuca lanceolata.
- Phyllodes. A phyllode is when a leaf stalk has taken the role of a leaf. Many wattle species have flat, single leaves, which really leaf stems or phyllodes. This adaption has the advantage that the leaf stalk has fewer pores on its surface than does a leaf through which water vapour can be lost e.g. Red-eyed Wattle, Acacia cyclops.
- Thickened leaves. Some species, in addition to growing in the coastal environment also grow in other areas away from the coast. Often when growing by the coast these plants appear to develop a much thicker leaf which has thicker covering of the protective surface, referred to as cuticle e.g. Quandong, Santalum acuminatum.
- Succulent plants. These are readily recognised as I am sure that you as children and your children have fun in squashing the leaves of succulent plants and seeing the fluid that results. These plants are able to store water for long periods but if there are extreme dry conditions these plants can die e.g. Coastal Pigface, Carpobrotus virescens.
- Shiny leaves. These reflect the heat away from the plant e.g. the young leaves of Thick Leaved Fan Flowers, Scaevola crassifolia.