Leaf Morphology

Shape Shifters

Extract from our online course Botany and its role in the ecosystem
Some plants exhibit morphological traits related to the environmental conditions in which they live. 

The most important physical factor which has the most impact on leaf shape is light.  Leaves that trail along the ground surface or are shaded by other vegetation get less light and tend to be larger. 

Using an Ivy leaf as an example

Ivy (Hedera helix) exhibits morphological traits dependent on its growth stage. The mature leaves of Ivy exhibit the flowers and fruits whereas the broader, lobed leaves are the immature leaves. The immature leaves tend to trail on the ground in the shade whilst the mature leaves climb to the light. The difference in shape and diameter between immature and mature leaf is thought to be in response to the need to photosynthesise, with the larger size of the immature leaf providing a greater surface area to gain maximum energy from sunlight.  The morphological difference may also be connected to the way that the immature plant takes up and transports nutrients via xylem and phloem (i.e. the need to develop shoots and grow quickly in order to reach light). In regards to evaporation, the larger immature leaf will not transpire as much as the mature leaf so can be bigger without risk of losing water.