Answers

2014-11-05T20:52:27+08:00
Spines help prevent water loss by reducing air flow close to the cactus and providing some shade.Spines help the cactus in several ways. The most obvious use of the spines is for protection against foragers. The cactus basically states "How much pain are you willing to indure to get a drink in this desert?"; Surprisingly, some animals do partake. In some cactus varieties the spines participate in water collection. Water from dew condenses on spines and, in some cactus species, downward-pointing spines help to direct rainwater to the roots of the plant. Spines help to reflect light away from the cactus stem theoretically lowering the stem temperature. Some spines also trap in a layer of air next to the cactus stem preventing loss of water via evaporative cooling.
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