Plants on other planets wouldn't necessarily be green. Cool.
What I've never understood, though, are the plants here on Earth that aren't green. We have a Japanese cherry tree in our front yard and it's leaves are like really dark purpley-red. How can it be that color and still undergo photosynthesis? Is there something different about its chlorophyll? Gunn, you're a horticulturist, enlighten me!
4 comments:
Oh, I only just noticed this and I've got to go to work.
It's the anthocyanins, Frank. They're more common than you'd think and are responsible for those lovely autumnal colors. When cool temperatures kill off the chlorophyll it's partly the anthocyanins that you see left over from the decomposition process. (There are also xanthophylls and carotenoids).
Basically these pigments capture light wavelengths that green chlorophylls can't. (They also play other roles in the plants flowers, etc.) Some plants are adapted to growing in shade through a different balance of pigments as they have to compete with the canopy above them.
However, freaks like the cherry tree in your garden (I grow a few here too) are maintained through cultivation due to ornamental value. (Amongst horticulturists the ornamental value of Prunus cerasifera cultivars are a matter of playful disagreement.) Left in a wild state there would be considerably fewer of these purple leaved plants. Still, I wouldn't be without the grand but somewhat sinister looking Copper Beech (Fagus sylvatica Purpurea group).
Thanks for the lesson, Gunn! So, what exactly is the function of these other pigments? Do they also produce energy via photosynthesis?
I have absolutely no idea, but I would guess that chlorophyll is mixed in with these pigments. And sometimes the pigments are in such a high proportion that the green is drowned out. The pigments capture the light (and perhaps convert them to usable wavelengths?).
Whoa, Esme, back off. I'm the horticulturist round here.
....sulk.....
But yeah, whatever, there's chlorophyll everywhere but in varying concentrations. The other pigments absorb and reflect different light wavelengths - hence the perceived color differences. Light energy stimulates that whole ... what was it? Oh yes, 'electron transport chain' which is part of the light dependant phase of photosynthesis. It's been a few years so I'm a little rusty but it's pretty fascinating the way that light energy is converted into chemical energy. Scientists have still not yet identified every stage in the process but know that it takes place. (Thus I couldn't resist forcing one of my atheist scientist friends to concede that we all had therefore to take photosynthesis on the basis of faith, which was amusing simply for it's own sake.)
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