May 18, 2017
This is an example of a modified stem of a plant. A modified stem of a plant is one that has evolved to carry out specialized functions besides those of a normal stem (support for a plant, transport of sugars and fluids, food storage). In this video, a cactus is shown. Cacti have evolved to have thick stems (surrounded by a thick cuticle layer to reduce water loss) to store ample amounts of water during rainfall in dry environments. Stems of cacti have also evolved to conduct photosynthesis without leaves (which, in this case, are spines).