All plants grow toward sunlight, except when then don’t. In nearly all cases, plant stems, vines, and bines grow upward, reaching for the sun’s energy. Plants deprived of sunlight will often grow longer than they can support, in an effort to reach that energy source. This is called etiolation. But, sometimes, it is better for a plant to grow away from sunlight. This behavior is called skototropism.
The dark side
Light levels are pretty dim at ground level in a thick jungle. If a vine does not find a tree to climb, it will die. If it heads toward visible light (an opening in the canopy), it will never find a tree to climb. Instead, these vines must grow toward the darkest place they can find (the base of a large tree) in order to find something big enough, strong enough, and tall enough, to provide support. What’s really interesting, is that larger trees attract more vines, while smaller trees attract less vines. There are even mathematical formulas that describe skototropism among certain jungle seedlings! Once a climbing plant has found a support structure, the skototropism behavior is turned off and upward growth (phototropism) begins in earnest. [Some scientists believe that roots grow down because of skototropism, while others believe it is something called gravitropism. You decide.]
4 Comments
utthaan
7/29/2018 01:25:41 pm
interesting. would like to know more of these
Reply
Martin McDaniel
9/3/2018 03:41:03 am
Of course it is the former. Skototrophism. It is growing downward not because it is being pulled downward as the term grivtrophusm implies. It is seeking to survive. It must be anchored in the Earth to do so. It also needs the the minerals an ground water in the soil. If gravity is pulling roots how is it that in many plants are able to resist in their upward parts which are weaker than their root systems this supposed gravitational pull.
Reply
3da
2/26/2022 10:51:07 am
Well, i once have a hanging pot of aloe vera.
Reply
Kate Russell
2/28/2022 09:11:44 am
It sounds like your aloe vera may have been rootbound. Also, since it was hanging, I imagine that there was sunlight peeking in that hole on the bottom, stimulating leaf, rather than root growth. Leave a Reply. |
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