• Question: How do cacti make their own food; they have no leaves for photosynthesis?

    Asked by to James, Jennifer, Kim, Liam, Ricardo on 18 Jun 2014. This question was also asked by .
    • Photo: Jennifer Stephens

      Jennifer Stephens answered on 18 Jun 2014:

      Hi 12sarsat
      Photosynthesis in cacti is slightly different from most plants and happens this way because they live in a very dry climate. Firstly, photosynthesis takes place in the stem, as you correctly say they do not have proper leaves. Secondly they take in carbon dioxide at night and use it the next day for photosynthesis. This means they can keep their stomata closed during the day to stop them losing lots of water. Stomata are tiny holes that they breathe through. In most plants carbon dioxide is taken in during the day and is not stored. This means plants are constantly losing water which evaporates when the stomata are open.

    • Photo: Ricardo Ramirez

      Ricardo Ramirez answered on 23 Jun 2014:

      They don’t have leaves, but they still have chloroplasts (they are green!) and they live in an environment where they have to take it slow (they have to work with a limited amount of water as well). What you find is that cacti tend to have a bigger surface in their “trunk”, so they still have plenty of light to work with.
      Also, some of them do have leaves:
      http://fineartamerica.com/featured/cactus-leaves-jesus-nicolas-castanon.html
      http://wonderlane.blogspot.co.uk/2012/01/white-spiked-cactus-with-little-red.html
      And some of the big leaves can be food!
      http://en.wikipedia.org/wiki/Nopal

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