And we’re back for our word of the week journey in myth and botany!

This week we veer into the darker corners of myth, cloaked in shadow and darkness.

Our word today is:

SKOTOTROPISM

 σκότος = skótos, “darkness” in Ancient Greek

• Cognates include:
  • Old Irish scáth,
  • Sanskrit छत्त्र = chattra, “umbrella”
  • Old English sceadu which becomes the common English shadow

τρόπος  = trópos, “a turn, way, manner, style, a trope or figure of speech, a mode in music, a mode or mood in logic” in Ancient Greek.

• Tropisms can be distinguished according to the orientation with respect to the direction of the stimulus – here it is towards darkness.

If you really wanted to, you could read the word as a ‘the turning to the darkness’.

Definition

Skototropism is defined in botany as a growth or movement toward darkness . It is commonly referred to as negative phototropism – a tendency to grow toward the light, which is common to most plants.

Phototropism refers to the way plants grow toward the sun. This is done by elongating plant cells on the side of the plant that is not receiving sunlight, hence the bend.

Negative phototropism means the bend (and ensuing growth) goes in the opposite direction, away from the sun.

There has been limited research around skototropism but it appears to concern mainly tropical vining plants. (Monstera, Pothos, Philodendron)

RESOURCES – Light & Nutrients

One of the biggest challenges to a plant in the jungle is getting enough sunlight.

They have plenty of moisture and soil nutrients so there is no problem on that front.

But the jungle canopy blocks most of the sunlight needed by the lower growing plants.

The vines eventually climb up the trees that make up the canopy, but how does a vine sort out where the tree is and which tree is best and tallest and strongest?

STRATEGY – Through the Darkness, Up to the Sky!

If it heads toward visible light – where there is no shade, no canopy – there cannot be a tree.

So the strategy seems to be that the vines must grow toward the darkest place they can find – like the base of a tree – so as to find a suitable climbing structure.

Once a climbing plant has found a support structure, the skototropism behavior is turned off and upward growth (phototropism) begins in earnest.

Research & Quotes :

Research into the health of the Agua Salud:

Another reason could be that the young forest canopy is too open for aroid seeds to germinate and grow. Unlike most plants, some aroids start out life growing away from light and towards darkness. (This has another great word: skototropism). It seems counterintuitive since most plants need light. But it is actually a good strategy. By growing away from light, aroid seedlings are more likely to run into a tree, which they need to climb up into the canopy and get to the light that they need to photosynthesize. So it is possible that there is too much light in the young forests and it keeps the aroid seedlings from finding a host tree.

Hard times for hemiepiphytes: Aroids have trouble making a comeback in second-growth forests
– Estefania Fernandez Barrancos

According to the studies of the Florida State University researchers, the vine Monstera gigantea can use skototropism from distances of 27.5 inches away to find its host tree. Once the vine reaches the tree and begins climbing, it abandons its skototropic behavior and becomes phototropic, putting, out saucer‐shaped leaves to manufacture food through photosynthesis.

TREE‐AIMING TRAIT OF PLANTS FOUND – Jane E Brody

Our experiments show that these vines are attracted to the darkest sector of the horizon. In nature trees provide these dark sectors. 

Donald R. Strong, Jr. and Thomas S. Ray, Jr

σκότος , ὁ, more rarely σκότος , εος, τό (v. sub fin.)
1. darkness, gloom, 
2. always of the darkness of death,
3. of the nether world, 
4. the darkness of the womb
5. of blindness

Henry George Liddell, Robert Scott, A Greek-English Lexicon