Nutrition

Dendrobium officinale is part of the plant kingdom and in fact undergoes the process of photosynthesis. Like other plants, D. officinale takes in carbon dioxide , water, and sunlight to produce sugar, oxygen, and water. The sugar created is called sucrose, which is a sugar that the orchid can utilize in cellular respiration. The oxygen produced can be used by other organisms, much like ourselves.

 

Photosynthesis occurs in the chloroplasts which are mostly within the leaves of the orchid. First, the stomata open to allow carbon dioxide into the leaves, and  chlorophyll within chloroplasts absorb the sunlight.  Within the chloroplasts there are thylakoids which do the light dependent reactions. Inside the thylakoids the carbon dioxide, water, and sunlight begin the photosynthesis process. In the first steps of photosynthesis, NADPH, a five carbon sugar, and ATP are formed which pass into the stroma and onto the calvin cycle. Once in the stroma the five carbon sugar undergoes a cycle which transforms that five carbon sugar into a usable sugar for the plant.

Water is brought up to the other plant organs through the use of xylem. First water is taken in by the root hairs and drawn through the dermal tissue (epidermis/skin), into the ground tissue, and finally into xylem. Once in the xylem, the water can travel up the stem into the leaves that are photosynthesizing. This water doesn’t move the way that you may assume, instead of being pushed up the stem by water pressure in roots, it is pulled up. When the stomata open to allow carbon dioxide to enter the leaves, water is released. The droplet of water released then causes the root hairs to pull in another droplet of water. The water is literally pulled up the orchid!

Now that water has moved up to the leaves to allow photosynthesis, the sucrose needs to move to the cells in the roots. The sucrose is transported down the stem through the use of vascular tissue called phloem. The phloem is composed of cells called sieve tube members which don’t have any nuclei! Sieve tube members need some help;  so, they have cells called companion cells which do have nuclei and lots of mitochondria that take over the metabolism for the sieve tube members. Sucrose can therefore can travel down from the leaves to roots and provide sugar to the rest of the orchid.

To learn how Dendrobium officinale reproduces check out my Reproduction page!
Return to Home page.