arial roots vs buried roots

[james mickelso]

In a few of the threads here there is an allusion to arial roots and roots that are buried being somehow different. Is there a difference? I have taken some pictures that hopefully will clarify for the new orchid growers here that there is no difference between the two other than misnomers. When a root grows, the tip is green and hard. That is where the growth occurs and the material hasn't yet differentiated into root (the inside wiry thread that carries food and moisture to the plant) and velamin (the spongy covering that absorbs the food and moisture for the root to then absorb). The velamin developed over who knows how many millions of years due to changing condition as orchids developed into what we have today. The spongy velamin very quickly aborbs water (nutrient and gas laden) and stores it for the root. During the start and end of the rainy season, this affords the orchid more moisture more frequently as during these times it rains sporadically. So any way, here are some pictures to show how this works. Notice that on the roots there are very white bright roots (these are new roots where the velamin hasn't swelled up yet and won't absorb water well) and darker roots (where the velamin has grown spongy and absorbs water immediately). If you take your orchid out of the pot and let the roots dry, you will see that they are the same as what has been called arial roots. As the root grows there is a time when the white velamin hasn't become spongy and is clearly shiny and harder than when th velamin has developed into the spongy water absorbing and retentive material the orchid needs to absorb nutrients and moisture. I hope this clarifies this aspect of orchid development for you.