why are cactus plants leaves spiny?

Answer 1

That shape and structure of leaf is able to better conserve water. You'll notice that a needle is essentially a narrow cylinder or very steep cone, and it has a much lower ratio of surface area to volume than a large, flat shape like a typical leaf. Water evaporates from the surface of a leaf, so having such a small surface prevents water from escaping into the dry desert air.

The needles do also protect the plant from animals that would otherwise try to eat it, but that is a secondary effect of the dry environment. Because there are no resevoirs of water in the environment, animals must consume plants for their moisture content. The spikes prevent the cactus from being eaten by such animals.

Answer 2

The cactus plants grow in desert areas .They have spiny leaves cause they need to reduce the evaporation.the spines have less surface area so there is less evaporation .

Answer 3

Plants curl their leaves up in dry conditions to conserve water (less surface area for water to be lost from in the process of transpiration). Cacti, over time did this more and more. THere were advantages to this in that they lost less water, but photosynthesised less (the stem has taken over this role in cacti). They also needed to save as much water (as who knows when they will get more water), so their stems swelled up. But animials liked the idea of a once stop nutrition and water stop. THe now redundant leaves became more use as protection to stop greedy animals chewing them! Over time the spines became very sharp and effective protection.

Answer 4

They are adapted to maintaining as much humidity as possible. Also, the way they stick to the cactus helps them a lot.

Answer 5

To protect them from being eaten by insects as they hold the water they need during a drought.

Answer 6

Sines have a smaller surface area so there is less area to loose water from. It also helps to protect them from crasong animals

Answer 7

leaves contain moisture and in the desert animals will eat the leaves for this reason as a matter of life and death. therefore the spines are a form of defense

Answer 8

the shape of the leaf helps to store water and any small animals, birds or insects that try and attack the plant to get to the water get stabbed.

Answer 9

It's a protection thing to keep animals and insects from eating them

Answer 10

that is naturs way of protecting them from getting eaten by the critters.