We can see numerous leaf structures in plant kingdom. As the leaves are designed for photosynthesis, their structure must be a factor for any optimization in photosynthesis or chlorophyll distribution.

This link describes many leaf structures but I cannot find what I am looking for in anywhere.

  1. I think taxonomy of plants deals with the flower structure but is their any relationship among plant species that we can describe with leaf structure ?
  2. Do the leaf structure is optimized for maximum photosynthesis rate if so then why these different structures ?
  3. Any other advantage for these diverse leaf structures ?
  • 2
    $\begingroup$ Two comments: 1) plant taxonomy takes multiple types of morphological traits into account + molecular information. Linneus original sexual system for plants was however based on flower morphology. 2) Leaf morphology is based on tradeoffs between many different functions, and besides the efficiency of photosynthesis you also need to take e.g. water loss (desiccation), nutrient/water transport and stability into account. Hence the diversity of structures. $\endgroup$ Mar 11 '15 at 10:19

1) Your understanding of taxonomy is outdated by a few hundred years. Linneaus' original system was based on flower morphology, but we since realized that the most effective taxonomy takes into account many different traits. In today's times, we mainly use DNA sequencing to determine relationships between organisms.

2) The leaf structure is not necessarily only optimized for maximum photosynthesis rate. For instance, the leaves of cacti are spines: thin and pointy to minimize water loss and defend the plant. In fact in cacti the stem is the photosynthetic part of the plant, not the leaves. More generally, leaves may be thicker or thinner to cope with drought. You can check out the wikipedia page for Specific Leaf Area for more information.

Long story short: different plants grow in different environmental conditions, so the optimal leaf shape for any one plant depends on conditions like drought and shade.

3) There are many advantages that can be conferred by leaf shape. One example is how leaf shape can affect what is known as the boundary layer of the leaf. The boundary layer is thicker in larger, uniformly-shaped leaves and thinner in dissected or compound leaves. The intro on this webpage seems like a good resource

Overall, good question. You have to keep in mind that any trait is going to be the product of many different factors; no one factor can entirely determine a trait's morphology. For leaves, it's many different factors including photosynthetic rate, drought, shade tolerance, defense against predators, etc. that determine the shape of the leaf.


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