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midnightsmum

Weekend Trivia ~ Saturday

Well, we know what makes plants green, right? Easy peasy, as they say. Good old chlorophyll. We can sometimes diagnose our plants by the colour of their leaves - my Christmas cactus, for example, has the leaves at the ends that are reddish, because they are sun-scalded. Now that the plant is inside, they will go back to green.

But not all leaves are green, right? I think of these things - why are many plants purple leaved? Like Persian shield, oyster plant and ornamental cabbage, or my Purple Heart Tradescantia. Or purple basil. Nice pops of colour in the garden, and a good science question.

But other leaves are turning colour right now, too, on a temporary basis. Maples are turning red, oaks are turing brown - other trees all sorts of oranges and yellows. The fall colours are stunning - it's what my Aunt who moved to Florida missed the most, and my Mum would wax leaves and send them to her. Sisterly love!! So how do they turn colour?

So, only 2 questions:

1. What is it that makes some leaves appear purple? There is a big long word which perhaps TM knows already - I'll accept a description of what it is.

2. What makes leaves turn colour in fall? A grade-school question, for sure, but perhaps we have forgotten?

I'll be back with clues!!

Nancy.

Comments (21)

  • aftermidnight Zone7b B.C. Canada
    9 years ago

    Mmmmm, I'm thinking for #1 it might be the same stuff that makes purple colored fruit and veggies so good for you :).

    #2 a certain substance is no longer produced because of the lack of something, it disappears leaving other stuff behind, does this make any sense LOL.

    Annette

  • thinman
    9 years ago

    Yes indeedy, I do know a few things about leaf colors, including the a-word, which applies to both questions. I'll bet others know the a-word too, due to it's becoming common in dietary usage.

    Heading off the the farmer's market.

    TM

  • cyn427 (z. 7, N. VA)
    9 years ago

    I agree with Annette for #2, but need more clues for #1. I will be trying to think of every a word I can now. Hmmm...

    Cynthia

  • midnightsmum (Z4, ON)
    Original Author
    9 years ago

    Now I did't know abou the dietary connection. Kinda flies in the face of one theory for the purple.

    Nancy.

  • midnightsmum (Z4, ON)
    Original Author
    9 years ago

    And yes, Annette - the a-word is what makes those purple fruits and veggies so good for you!! It is also part of the "French paradox", that phenomenon that allows the red wine drinkers of France and Italy to enjoy a much lower rate of heart disease while enjoying a far fattier diet than say, North Americans. Hmmmm...any help?

    Nancy.

  • cyn427 (z. 7, N. VA)
    9 years ago

    Attention Deficit Disorder? The plants can't focus well enough to stick with chlorophyll???

    ;)
    Cynthia

  • midnightsmum (Z4, ON)
    Original Author
    9 years ago

    Good one, Cynthia!!

    Green plants contain a lot of the pigment chlorophyll. Because chlorophyll molecules are very good at soaking up blue and red light but not so good at absorbing green light plants containing a lot of chlorophyll appear green to the human eye.

    Pigment is also behind a purple plant's vivid coloring. Plants that appear purple, blue or red contain a higher concentration of 'a' than chlorophyll. 'A' is a pigment adept at absorbing green light, but less skilled at absorbing red, blue or purple light.

    Some scientists think that because 'a' often appear together with high concentrations of poisonous phenols, it's possible that the purple leaves of some plants help ward off hungry herbivores. Yet many of the purple fruits, veg and herbs are good for us - very confusing.

    Nancy.

  • mnwsgal
    9 years ago

    I think I know the a word. Thought purple grapes for wine are good due to the r word.

    Just popping in before I run more errands. Went to a customer appreciation day event this morning. Bought a red 'Salsa' helenium.

  • thinman
    9 years ago

    The a-word sounds a little like it might be poisonous, but that particular four letter combo just means blue, not that it will turn you blue in a very final way.

    TM

  • aftermidnight Zone7b B.C. Canada
    9 years ago

    Bobbie 'Salsa' is a really pretty Helenium, I just bought 'Hot Lava' my pot ghetto is growing by leaps and bound :).
    Right now I'm playing musical chairs with some of my clematis, found spots for two of those 'Proteus' divisions I divided a while back. Dug out a peony 'Sam Donaldson' had it for years, it just won't bloom for me so it's history, it was planted at the base of my Moroccan Broom. Sooooo it's now replaced it with a clematis, 'x durandii', and one of the 'Proteus' divisions is planted where the 'x durandii' was, the the second 'Proteus' is now planted on the pergola to go up the trunk of a Wisteria only inches away from where it was originally planted, I just have to find a home for the third one, see what I mean about musical chairs LOL.
    Bonus, several 'Waterlily ' colchicums are blooming around where I dug that huge clematis, I thought I had lost them, they are persistent, not even I could kill them, soon as they've finished blooming I'll move them too.

    Annette

  • cyn427 (z. 7, N. VA)
    9 years ago

    Hmmm, still not coming up with the "a" word. Thought of cyan as blue, but that can't be it. Thought of the one that goes with old lace, but not four letters and certainly poisonous. Sigh. My brain is as lazy as my body today.

    Cynthia

  • thinman
    9 years ago

    Cynthia, your first thought is a good one. It will give you the third and fourth syllables of the five syllable a-word.

    TM

  • mnwsgal
    9 years ago

    An' tho cyan is in the word it is a reddish pigment instead of blue, Cynthia. Good ADD joke.

    Sounds like a very productive day, Annette. I also have a few clematis to plant from my holding bed. Several were started from seed and have finally bloomed so I know what they are and if I want to keep them. We had a rain shower shortly after I returned home which put off planting until tomorrow. Not a lot of rain so it shouldn't be too muddy as the ground was getting a bit dry.

    The Salsa is a lovely red. I like that it is a shorter variety. Hot Lava looks very nice as well.

    This post was edited by mnwsgal on Sun, Sep 21, 14 at 10:40

  • cyn427 (z. 7, N. VA)
    9 years ago

    Bobbie, cyan is actually a blue color if I remember correctly. Between blue and green on the color wheel.

    Still don't have the answer though.

    Cynthia

  • mnwsgal
    9 years ago

    Sorry I wasn't clear. I know cyan is blue. The a word which contains the letters cyan is the reddish pigment.

  • aftermidnight Zone7b B.C. Canada
    9 years ago

    #1. Anthocyanins (sp?)
    #2. Short answer, leaves stop producing chlorophyll.

    Annette

  • mnwsgal
    9 years ago

    Agree with Annette's answers.

    1. An tho cyan in, anthocyanin
    2. Chlorophyll decreases and anthocyanin increases.

    This post was edited by mnwsgal on Sun, Sep 21, 14 at 11:47

  • midnightsmum (Z4, ON)
    Original Author
    9 years ago

    Sounds like your gardens are still doing well!! Ours is starting to fade. I picked a few red tomatoes off, but an leaving the green ones - hoping this bit of mild weather holds; or we'll have fried green tomatoes!!

    OK, you guys are good, with TM & Bobbie's excellent clues.

    1. Yes. Anthocyanin pigments are responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers. They have long been the subject of investigation by botanists and plant physiologists because of their roles as pollination attractants and phytoprotective agents. They have also been very useful in taxonomic studies. Today, interest in anthocyanin pigments has intensified because of their possible health benefits as dietary antioxidants. Over 300 structurally distinct anthocyanins have been identified in nature. Anthocyanins are one class of flavonoid compounds, which are widely distributed plant polyphenols. Resveratrol, btw, is another phenol.

    2. During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves.
    As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.
    The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color.

    So there you go - an interesting question - I should done a little more research into the cause and effect of anthocyanin. I am truly impressed that you winkled that answer out.

    So, for all:
    {{gwi:612249}}{{gwi:612249}}{{gwi:612249}}{{gwi:612249}}

    Thanks for playing and putting up with my feeble clues. See you next week!!

    Nancy.

    Here is a link that might be useful: An interesting article about research into Anthocyanin

  • mnwsgal
    9 years ago

    Thanks for question and the maple leaves. Interesting article about the research on properties and effects of anthocyanins in foods.

  • thinman
    9 years ago

    Thanks for the four maple leaves, Nancy It's a very interesting subject to me. In my chemistry classes we used to extract the chlorophyll from green leaves and reveal the yellow color left behind.

    If you don't mind, here are a few more details on the anthocyanins in fall, just for the general education of us all. It also explains why apples and grapes don't turn red or purple until they are ripe and why apples can be red on only one side.

    A third pigment, or class of pigments, that occur in leaves are the anthocyanins. Anthocyanins absorb blue, blue-green, and green light. Therefore, the light reflected by leaves containing anthocyanins appears red. Unlike chlorophyll and carotene, anthocyanins are not attached to cell membranes, but are dissolved in the cell sap. The color produced by these pigments is sensitive to the pH of the cell sap. If the sap is quite acidic, the pigments impart a bright red color; if the sap is less acidic, its color is more purple. Anthocyanin pigments are responsible for the red skin of ripe apples and the purple of ripe grapes. Anthocyanins are formed by a reaction between sugars and certain proteins in cell sap. This reaction does not occur until the concentration of sugar in the sap is quite high. The reaction also requires light. This is why apples often appear red on one side and green on the other; the red side was in the sun and the green side was in shade.

    Quote is from the University of Wisconsin.

    TM

    Here is a link that might be useful: Fall colors.

  • midnightsmum (Z4, ON)
    Original Author
    9 years ago

    Interesting article TM - that picture is a bit like what i see out my second storey windows now, over towards the river.

    Nancy.

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