Photosynthesis of varigated leaves

[Steve Bullman]

I have asked this question in the past but never had a definitive answer.

do varigated leaves and purple leaves etc which have their clorophyll masked by various other pigments suffer any ill health because of it? It would seem, at least to me that the photosynthesis wouldnt be as efficient. I know some trees ie copper beech seem more succeptible to disease and ill health that common beech....how much of this is due to the above question?

[Pete Mctree]

When a variagated species starts to revert to normal pigmented growth, it is usually a sign of stress. The lighter shades of green in the leaves usually photosynthesise at a lower efficiency, hence the reversion is a method of increasing productivity

[Dagmar]

This was a question that I remember from college:

 

The answer is pretty well as stated, the research done in the the late eighties, and reported in New Scientist magazine, on the First of September 1990

 

Plants that have variegated or mottled leaves are less efficient at generating energy by photosynthesis than plants with completely green leaves, and botanists have long wondered how they are able to compete in the wild. Now, it seems that such patterned leaves have the advantage of being better camouflaged, and that this outweighs the disadvantage of reduced photosynthesis. According to Thomas Givnish of the University of Wisconsin, the camouflage of patterned leaves makes the plants less likely to be eaten by herbivores (Functional Ecology, vol 4, p 463).

 

Variegated plants have leaves with patches or stripes of white or yellow. The patches lack chlorophyll, making them less efficient at photosynthesis than leaves that are green all over. Ornamental plants with purple, red, or pink mottling are also less efficient because the mottling masks the chlorophyll.

 

For some time, botanists have known that variegated and mottled leaves are found in species of 'understorey' herbs which grow in temperate and tropical woodlands and forests. Givnish says that against the sun-dappled floor of a forest, animals without colour vision, including many vertebrate herbivores, such as deer, cannot spot variegated leaves. He believes that in a world lacking colour, variegation and mottling may disrupt the outline of leaves, making them harder to find.

 

Givnish points out that this kind of camouflage will work only when the leaves are close to the ground. On a bush, against an out-of-focus background, even colour blind animals should be able to see them quite easily.

 

The camouflage theory is supported by a recent survey of the wild plants of the north-eastern US. Mottled and variegated leaves occur almost exclusively on herbs of the forest floor. These live in conditions in which botanists would expect that efficient photosynthesis would be less important to the plants' survival than avoiding being eaten by vertebrate herbivores.

 

This postulation applies broadly to plants although a tree is a complex large plant so there is no reason to believe that the theory does not apply. Species that are variegated are, in some cases, noted to lose variagation higher up the the plant, pointing to the possibility that this is an evolutionary 'trick' to avoid being eaten. Of course it is irrelevent in many zones as the amimals that may have fed on the trees in question are either extinct or the tree has moved out of the animals normal range. In itself this would also make the tree or any other plant that has variageted foliage suseptible to disease and failure, if it were existing on the limit of its natural range.

[Steve Bullman]

thanks dagmar...i wonder if theres any more recent study on this, beings as that paper is 16-17 years old? good find all the same though.

 

in your work do you come across many fruit trees with variegated leaves and is the fruit production as high?

[Dagmar]

I know what you mean, but Givnishs' work is pretty well regarded and it is unlikely that any more studies have found any alternative reasons for the incidences of variegation.

 

As to fruit trees and variegation, this would be a sympton of viral infection and would be treated accordingly, either by removal of the infected parts of destroying the tree, on commercial orchards anyway. On smaller more traditional plantings then it is not quite so serious a prospect as the fruit will be grown for the flavour and/or specific uses as opposed to purely yeild. As to whether the tree will produce less fruit, if the variegation occurs as a symptom of poor or failing health, then I would expect that the fruit yeild would lessen as the infection grew. A good example would be the effect of peach leaf curl ,Taphrina deformans which causes variegation and results in severe fruit drop,(of immature fruit), and the deformation of mature[ing] fruits.

[Dagmar]

This is from the Herald Tribune in Florida

 

A palm tree worth 20 grand?

Botanists say it just might be Genetic mutation puts two-tone fronds on Sabal palmetto

 

BY CHRISTOPHER O'DONNELL

 

 

 

MANATEE COUNTY -- Most people would not look twice at the raggedy-looking cabbage palm.

 

But they might if they knew its price tag.

 

A typical cabbage palm costs about $120. One found on a field soon to be cleared for an industrial park and hotel, however, could be worth as much as $20,000, according to one local tree company.

 

Known as a variegated Sabal palmetto, the tree is a one-in-a-million genetic accident that is almost impossible to value, say experts at Marie Selby Botanical Gardens in Sarasota.

 

The tree, which was donated to Selby by developer Anthony Mazzucca, was replanted in its new home close to the Selby House on Friday.

 

"I couldn't put a price on it," said Harry Luther, curator of Living Collections at Selby. "You couldn't go out and buy one."

 

But the tree might have been destroyed had Dennis Cathcart, the owner of Tropiflora, a plant nursery in Tallevast, not spotted it while driving past the plot of land in the southeast corner of U.S. 301 and Tallevast Road.

 

Cathcart, who travels all over the world looking for unusual plants to sell, has seen two other variegated trees destroyed by development. The trees were likely discarded by people who did not recognize their value.

 

"He's trained his eye to see something different," said his wife, Linda. "He kept it in the back of his mind. When he saw the land was going to be sold, he contacted the owners."

 

Sabal palmettos are the most common palm tree in the southeast United States and a staple of Florida's natural and planned landscapes.

 

Every so often, a tree develops with a genetic mutation that prevents it from photosynthesizing normally. It results in fronds that are a mix of green and gold.

 

The tree donated to Selby, estimated to be between 20 and 30 years old, has fronds trimmed with gold that glints in the sun.

 

But the mutated gene that produces the unusual coloring is recessive, meaning it is almost never passed on when seeds from the tree take root. It can also make the trees less robust than normal ones.

 

It is that combination that makes the tree so rare.

 

"I've been doing this for 40 years and I've only seen two of them," said Darrel Turner, owner of Turner Tree and Landscape, which moved the tree to Selby for free. "It's very symmetrical; the way it's variegated is perfect."

 

So I'll be keeping my eyes open.

[Steve Bullman]

i'll bet!!

where did u find the article? was there a picture?

[Dagmar]

It not that good but does show a comparision with the normal Cabbage Palm.