Tree Leaf Design, Shape and Function

Leaves Autumn 065

Leaves are the food factories of trees converting light into food via photosynthesis. Carbon dioxide is absorbed by leaves and converted using chlorophyll and water into carbohydrates or tree food. Oxygen is a bi-product of photosynthesis.
Tree trunks and branches of trees are designed to get the canopy of leaves in a position to receive the optimum amount of light.

Common Leaf Shapes

You Can Tell a Tree By it’s Leaf

  • Trees are classified by their leaf in that evergreen trees keep their leaves all year around whilst deciduous trees shed their leaves annually usually in autumn.
  • Various leaves are described by their shape. The names created often have some reference to the shape Ovate leaves bear a resemblance to egg shaped and Lanceloate to a lance or spear.
  • The bottom half of the leaf where it attaches to the tree twig or branch can also have distinguishing features as shown above.
  • Leaf colour varies from yellow to coppery red but the majority of leaves are a form of green.

Leaves

Leaf Texture and Margin

  • This infographic looks at the edge of the leaf or ‘margin’.
  • Serrations are known as toothed whilst smooth edges are known as ‘entire’.
  • Ciliate leaves have hairs, eye lashes or short spines whilst pectinate has spiky edges
  • Texture can be another distinguishing features when trying to identify a tree from its leaves. Rough, leathery, fine, smooth, hairy, glossy, spiky etc each tree leaf has its own characteristic.
  • The underside of the leaf may have a different colouring

barrow Leaves

Other Leaf Issues

  • The above infographic includes more leaf shapes but shows how leaves are arranged on a stem.
  • Bipinnate has sets of pinnate leaves opposite each other.
  • Petiole is the leaves mini stem that attaches a leaf to the node or axil.
  • Trifoliate has three leaves at the end of a leaf stalk or petiole
  • The size and shape of the leaf can be affected by the position and age of the tree and where the leaf is growing.
  • Conifers often have needles which are flat or rounded individual or clustered. Alternatively they may have frondy fern like leaves

Notes
Composted and rotted tree leaves do not have much nutritional value. All the food has been given to the tree.
Composted leaves add humus and improve the texture of your soil.
‘Tree Root and Branch Reviews’ in our category section give some description of individual tree leaves

Credits
The Oxford book of Trees – B E Nicholson & A R Clapham
Hilliers Manual of Trees and Shrubs – H G Hillier
Ultimate Guide to Trees – Jenny Linford
Botany of leaves
Special and Extraordinary Leaves


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