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I have read that chlorophyll absorbs red and blue.

As shown in detail in the absorption spectra, chlorophyll absorbs light in the red (long wavelength) and the blue (short wavelength) regions of the visible light spectrum. Green light is not absorbed but reflected, making the plant appear green. Chlorophyll is found in the chloroplasts of plants.

It did not mention what the difference in chlorophyll between a red leafed plant and a green plant?

Does chlorophyll only come in green? So what in chlorophyll determines if other colors than green are reflected in plants that are naturally red? If chlorophyll needed can only be green would not the color green and the red from a " pigment" look brown?

Japanese Blood Grass enter image description here

Blue Selaginella

enter image description here

Solenostemon scutellarioides enter image description here

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    $\begingroup$ Plants contain many compounds that are not chlorophyll, for one. $\endgroup$ – Chris Dec 11 '17 at 23:50
  • $\begingroup$ Please provide some examples of plants that naturally - that is, not as a result of human selective breeding - have red leaves. $\endgroup$ – jamesqf Dec 12 '17 at 19:03
  • $\begingroup$ @jamesqf i made one working on more $\endgroup$ – Procreator Dec 12 '17 at 22:51
  • $\begingroup$ @Procreator: The examples so far seem to be the result of human selective breeding.. Plants have other pigments in their leaves, as you can see when leaves change color in the fall. That's caused by the breakdown of chlorophyll, allowing the other colors to show. In the first two of your examples, you can see that there is clorophyll showing in parts of the leaves. It's just that the intense pigment in the blood grass and the internal structure of the blue leaves masks the green of the chlorophyll. I expect something similar would be true of the coleus. $\endgroup$ – jamesqf Dec 13 '17 at 4:06
  • $\begingroup$ Are you sure all the example are selective breeding? I didn't check either, but if there is presents of chlorophyll as in normal plants the color green and the red pigment would blend to make brown. $\endgroup$ – Procreator Dec 13 '17 at 4:14
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Tl;dr : Some plants reflect green while others don't simply because some plants are green while others are not.

Plants contain chlorophyll, but are not 100% made of it. Parts of the plant that contain a high amount of chlorophyll will look green, (Leaves, stem) while other parts that contain less chlorophyll and contain more of other pigments will look different. The flower looks red because it contains a lot more red pigment than any other pigments. The fruit looks yellow because it contains a lot more yellow than other pigments. Carotene(orange) and Xanthophylls(yellow) are examples for pigments which absorb all colors except orange and yellow respectively, they reflect these colors. so it appears to be orange or yellow.

"Chlorophyll absorbs red and blue" is just another way of saying chlorophyll is green in colour.

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  • $\begingroup$ I think the confusion is why some plants have a benefit to have less clorophyll and others more. $\endgroup$ – MaDrung Dec 12 '17 at 7:15
  • $\begingroup$ @MaDrung then it's not a physics question anymore. I'll wait for op to clarify. $\endgroup$ – See Jian Shin Dec 12 '17 at 7:32
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    $\begingroup$ This question is surely off topic here, but as long as you've answered in this way, it might just bear pointing out that different structures have different purposes. A red flower may be intended to attract pollinators that wouldn't notice just another green thing. A tree trunk (the purpose of which is support and transport) might be gray due to weathering or red due to the presence of protective tannins. $\endgroup$ – Mike Dec 12 '17 at 15:51
  • $\begingroup$ @Mike a red plant not flower. $\endgroup$ – Procreator Dec 12 '17 at 17:09
  • $\begingroup$ Can you clarify what the pigments are made of? $\endgroup$ – Procreator Dec 13 '17 at 2:04
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All photosynthetic plants contain chlorophyll, and chlorophyll is green (leaving out various algae). Plant leaves often contain other pigments, which can mask the chlorophyll's green, or be masked by it.

A common example of the latter is the color of autumn leaves. The leaves contain various pigments such as xanthophylls, anthocyanins, and carotenoids that are generally masked by the green of the chlorophyll. As the trees prepare to drop their leaves in the fall, the chlorophyll decomposes, allowing the other pigments to become visible. Exactly what purpose(s) these other pigments serve isn't entirely clear. Some are thought to make photosynthesis more efficient, others might have functions where the color is irrelevant. See e.g. http://www.usna.usda.gov/PhotoGallery/FallFoliage/ScienceFallColor.html

Some plants may have a larger than average amount of other pigments, somewhat masking the chlorophyll's green, and giving rise to different shades of leaf color. Human selective breeding can increase these differences, giving rise to e.g. the purple-leaf plum or the almost golden color of some honey locusts: https://www.thespruce.com/trees-and-shrubs-with-purple-leaves-3269731

Other plants, like the coleus, may have chloroplasts only in certain zones of the leaf, allowing other color combinations, which can be wildly amplified by human breeding: plantcaretoday.com/colorful-coleus-plants.html

Sometimes the colors can be structural, as with the Blue Selaginella pictured in the question, or the grayish colors of desert plants that are produced by protective hairs: http://mojavedesert.net/plants/plant-adaptations.html

Finally, there are plants that don't have chlorophyll at all, but these don't photosynthesize. An example (common to the mountains hereabouts) is the brilliant red snow plant: enter image description here fs.fed.us/wildflowers/plant-of-the-week/… But it doesn't use the red pigment to photosynthesize, having become parasitic on soil fungi.

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  • $\begingroup$ Can you eat it? $\endgroup$ – Procreator Dec 14 '17 at 19:56
  • $\begingroup$ @Procreator: Eat what? The snow plant? Supposedly yes, but they're illegal to pick. Supposedly because they're rare, but they seem quite common in the mountains around here: scenicwonders.com/blog/rare-snow-plant-in-yosemite-west $\endgroup$ – jamesqf Dec 15 '17 at 18:19
  • $\begingroup$ In a survival situation.is why I was asking. $\endgroup$ – Procreator Dec 16 '17 at 4:02

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