- Height of the plant
- Diameter of stem or trunk
- Number of shoots, leaves or flowers.
These features can be altered within a relatively short period to cope with modifications in conditions, for example more sun when surrounding trees fall or more shade as surrounding trees mature; periods of drought or rain or the depth of the soil. Seed germinating on shallow soil will have a different root structure and growth than seed lucky enough to land on deep soil.
Characteristics that are not so plastic in terms of environment include flower morphology, leaf shape and leaf serration.
Advantages
Various studies have noted that leaf size tends to be larger in climates with high precipitation and more plants will have entire leaf margins in warmer areas. Leaf size is thought to be related to the balance a leaf must strike between photosynthesis and transpiration. Large leaf size raises the leaf temperature and increases photosynthesis which also increases transpiration, requiring larger root systems to maintain sufficient moisture in the leaves. In dry climates, the energy cost of replacing moisture outweighs the advantage of the increased photosynthesis of larger leaves, making smaller leaves more efficient.
Plant leaves are susceptible to environmental moisture. If there is too much, they can mold; if not enough they will lose too much through transpiration and wilt. Leaf size and shape can affect the rate that leaves lose water. Smaller leaves, with a larger layer of air space around them, lose water more slowly in relation to their leaf area than larger leaves. Tropical rainforest plants tend to have large, flat leaves while plants in arid climates have small leaves.
Shade adapted leaves tend to be larger and thinner which increases photosynthesis since there is more leaf mass. Thinner leaves have lower respiration rates per unit of leaf area. It appears that leaf size and texture are trade-offs that plants make to cope with the amount of light and moisture available.
Much less is known about the advantage that a particular leaf shape confers. Conflicting theories abound. Some think that smoother leaf margins on evergreen leaves may be because they tend to be thicker than deciduous leaves, allowing for more growth between leaf ribs. Some believe the smoother leaf margins occur because they require a denser network of veins than toothed margins, providing a better water supply which is more advantageous for evergreen leaves.
Kate Ravilious, in her article, Leaf Shapes and Climate Clues notes:
"In 1910 two explorers, Bailey and Sinnott, happened to notice that the shapes of leaves on the plants and trees appeared to be closely related to the climate of the area. The most noticeable trait was that trees that grew in warm places had large leaves with smooth edges, while trees that grew in cold places tended to have smaller leaves with very serrated edges.
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