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Hey - I'm the author of this piece. Thanks for voting it up to the front page. I love finding cool science in ordinary/everyday places, and am curious to hear p

by aatish 12y ago

Hey - I'm the author of this piece. Thanks for voting it up to the front page. I love finding cool science in ordinary/everyday places, and am curious to hear people's responses to the piece. Cheers.

giarc 12y ago
Could it be that long ago leaves existed without the wax, and when it rained the leaves were weighed down by all the excess water they were absorbing? Leaves with mutations producing wax were able to recover from a heavy rainstorm better than leaves with no wax. Picture a leaf in the Amazon, do you picture a big, waxy leaf? I do. Rainforest = more rain = more wax.
- hrjet 12y ago
  That's my first thought too. Moreover, letting the water roll off the leaves and down near the stem would help moistening the soil near the roots, which would ultimately benefit the plant.
  - giarc 12y ago
    The wax could also refract sunlight better.
maxerickson 12y ago
The waxy layer is believed to have developed as plants moved out of the water onto land, it helps to retain water: http://en.wikipedia.org/wiki/Plant_cuticle http://en.wikipedia.org/wiki/Plant_cuticle
- rcthompson 12y ago
  That explains the need for a waxy layer, but it doesn't explain the need for the superhydrophobic bed-of-needles surface.
  - fragsworth 12y ago
    Two possibilities: One, a superhydrophobic surface reduces the surface area of the water that lands on the plant, allowing less of it to evaporate and more of it to fall to the ground. Two, it may help prevent plant diseases by allowing less water to attach to surfaces that are prone to becoming diseased.
    - tempestn 12y ago
      That was my first thought. It's not a good idea to water your plants at night, because without the sunlight and heat of the day the water doesn't evaporate as quickly. Water sitting on the leaves all night can cause fungus and such things to grow, which is bad for the plant. Since plants can't avoid being rained on at night, it seems logical that they would evolve a mechanism for staying as dry as possible.
  - maxerickson 12y ago
    My first guess would be that it requires less energy to produce and maintain than other similarly effective arrangements of the wax.
  - fit2rule 12y ago
    Leaves blow around in the wind. If water was not being repelled from the underneath of the leaf, it would gain added weight, and have the potential of anchoring the leaf in the wrong direction. Repelling water from the underneath of the leaf keeps the leaf light, which allows the rest of the plant structure to support the leaf in the proper orientation.
mrb 12y ago
Maybe leaves evolved these microscopic "needles" in order to increase their surface area, because this would help photosynthesis for 2 reasons: 1. More surface area = better ability to capture carbon dioxide from the air. 2. More surface area = heatsink effect = reduced heating under the sun (photosynthesis is less efficient under too much heat[1]). The fact that these "needles" also create a superhydrophobic effect would just be a side effect. [1] http://www.ncbi.nlm.nih.gov/pubmed/21029116 http://www.ncbi.nlm.nih.gov/pubmed/21029116
- aatish 12y ago
  Hi. The needles are wax structures that protrude from the leaf, they aren't part of the leaf. So the added surface area doesn't absorb any air, and I doubt it helps in evaporative cooling either.
amanfredi 12y ago
Hi Aatish! I enjoyed it quite a bit. The fibers on the bottom of the leaf may not be significant -- perhaps they are vestigial and only the upper ones provide an advantage. Alternatively, heavy rain and wind can flip leaves upside down, blow plants over, and splash dirt and water up onto the underside of the leaves, so maybe it is an advantage for the whole leaf to shed water.
- aatish 12y ago
  Hey, I know an A. Manfredi. Are you Anthony from Swat?
  - amanfredi 12y ago
    Yes indeed :)
    - aatish 12y ago
      Sweet. Hi! This is an odd place to bump into you. :) I agree with your thoughts that this could be a consequence of coating the top surface in the waxy needles. However, I think it's actually somewhat unusual for a leaf to be superhydrophobic on the top and bottom, so I was wondering if there was some specific advantage to this leaf. Also, the needles on the under-side seemed far more dense than those on top, which was interesting.
asimpletune 12y ago
I believe the explanation for why the leaves are so hydrophobic is quite simple. Those leaves are huge. Since they are so huge, they act as a canopy, preventing needed water from reaching the ground... unless the water could just somehow bead up and roll off the leaf. Saying a leaf is hydrophobic is another way of saying that water doesn't stick to them. If water doesn't stick to them, it falls off. Very simple, and ingenious!

by aatish 12y ago

Hey - I'm the author of this piece. Thanks for voting it up to the front page. I love finding cool science in ordinary/everyday places, and am curious to hear people's responses to the piece. Cheers.

giarc 12y ago

Could it be that long ago leaves existed without the wax, and when it rained the leaves were weighed down by all the excess water they were absorbing? Leaves with mutations producing wax were able to recover from a heavy rainstorm better than leaves with no wax. Picture a leaf in the Amazon, do you picture a big, waxy leaf? I do. Rainforest = more rain = more wax.

hrjet 12y ago
That's my first thought too. Moreover, letting the water roll off the leaves and down near the stem would help moistening the soil near the roots, which would ultimately benefit the plant.
- giarc 12y ago
  The wax could also refract sunlight better.

maxerickson 12y ago

The waxy layer is believed to have developed as plants moved out of the water onto land, it helps to retain water: http://en.wikipedia.org/wiki/Plant_cuticle http://en.wikipedia.org/wiki/Plant_cuticle

rcthompson 12y ago
That explains the need for a waxy layer, but it doesn't explain the need for the superhydrophobic bed-of-needles surface.
- fragsworth 12y ago
  Two possibilities: One, a superhydrophobic surface reduces the surface area of the water that lands on the plant, allowing less of it to evaporate and more of it to fall to the ground. Two, it may help prevent plant diseases by allowing less water to attach to surfaces that are prone to becoming diseased.
  - tempestn 12y ago
    That was my first thought. It's not a good idea to water your plants at night, because without the sunlight and heat of the day the water doesn't evaporate as quickly. Water sitting on the leaves all night can cause fungus and such things to grow, which is bad for the plant. Since plants can't avoid being rained on at night, it seems logical that they would evolve a mechanism for staying as dry as possible.
- maxerickson 12y ago
  My first guess would be that it requires less energy to produce and maintain than other similarly effective arrangements of the wax.
- fit2rule 12y ago
  Leaves blow around in the wind. If water was not being repelled from the underneath of the leaf, it would gain added weight, and have the potential of anchoring the leaf in the wrong direction. Repelling water from the underneath of the leaf keeps the leaf light, which allows the rest of the plant structure to support the leaf in the proper orientation.

mrb 12y ago

Maybe leaves evolved these microscopic "needles" in order to increase their surface area, because this would help photosynthesis for 2 reasons: 1. More surface area = better ability to capture carbon dioxide from the air. 2. More surface area = heatsink effect = reduced heating under the sun (photosynthesis is less efficient under too much heat[1]). The fact that these "needles" also create a superhydrophobic effect would just be a side effect. [1] http://www.ncbi.nlm.nih.gov/pubmed/21029116 http://www.ncbi.nlm.nih.gov/pubmed/21029116

aatish 12y ago
Hi. The needles are wax structures that protrude from the leaf, they aren't part of the leaf. So the added surface area doesn't absorb any air, and I doubt it helps in evaporative cooling either.

amanfredi 12y ago

Hi Aatish! I enjoyed it quite a bit. The fibers on the bottom of the leaf may not be significant -- perhaps they are vestigial and only the upper ones provide an advantage. Alternatively, heavy rain and wind can flip leaves upside down, blow plants over, and splash dirt and water up onto the underside of the leaves, so maybe it is an advantage for the whole leaf to shed water.

aatish 12y ago
Hey, I know an A. Manfredi. Are you Anthony from Swat?
- amanfredi 12y ago
  Yes indeed :)
  - aatish 12y ago
    Sweet. Hi! This is an odd place to bump into you. :) I agree with your thoughts that this could be a consequence of coating the top surface in the waxy needles. However, I think it's actually somewhat unusual for a leaf to be superhydrophobic on the top and bottom, so I was wondering if there was some specific advantage to this leaf. Also, the needles on the under-side seemed far more dense than those on top, which was interesting.

asimpletune 12y ago

I believe the explanation for why the leaves are so hydrophobic is quite simple. Those leaves are huge. Since they are so huge, they act as a canopy, preventing needed water from reaching the ground... unless the water could just somehow bead up and roll off the leaf. Saying a leaf is hydrophobic is another way of saying that water doesn't stick to them. If water doesn't stick to them, it falls off. Very simple, and ingenious!