Convergent Evolution of Cactus with other Succulents ... 2/3

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Cacti and other Succulents

In the final example above the plants have adapted or evolved to their environment by their shape (morphology). These two unrelated plants (cacti and Euphorbias) in different parts of the world, but under similar conditions of water availability and temperature have evolved similar forms. To the "general public" the succulents of Africa can be confused with the cacti of the Americas, even though the plants are unrelated. This similarity of shape according to similarity of environment for unrelated plants is called Convergent Evolution.

The similar forms/shapes/features are:

• Round body shape or
• Upright candle shape
• Reduced or no leaves on plant
• Spines/thorns on the plant body
• Water storage within the plant

Each of these adaptations suits a plant in water limited environments:

A round body shape results in the least surface area for volume of plant, and less surface area means less exposure to the sun and drying winds while enabling the maximum storage of water within the body.

An upright candle shape exposes the least amount of surface area to the harsh sunlight, when the sun is directly overhead and at it's strongest.

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