The plant that pretends to be ill

A leaf damaged by mining moths (left) compared to one faking it (right).

A plant that pretends to be ill has been found growing in the rain forests of Ecuador. The plants feigns sickness to stop it being attacked by insect pests known as mining moths, which would otherwise eat its healthy leaves.

It is the first known example of a plant that mimics being ill, and could also explain a common pattern seen on plant leaves known as variegation.

The discovery is published in the journal Evolutionary Ecology.

Variegation is familiar to gardeners and affects many species of plant. Variegated plants have different coloured patterns on the leaf surface, produced by a variety of causes. One of the most common is when cells in the leaf lose chlorophyll and their ability to photosynthesise, appearing white. Canna 'Stuttgart' is an example of that type of variegation.

In theory, plants with variegated leaves should be at a disadvantage, because of this restricted ability to photosynthesise. But a chance discovery by a team of botanists suggests this may not be true after all. Instead, some variegated plants may be mimicking illness to avoid being eaten, putting themselves at an advantage.

"I was quite surprised," says Liede-Schumann. She believes that the plant essentially fakes being ill, producing variegated leaves that mimic those that have already been damaged by mining moth larvae. That deters the moths from laying any further larvae on the leaves, as the insects assume the previous caterpillars have already eaten most of the leaves' nutrients.

"The fact that there are both plain green and variegated leaves in the population indicates to me that both are useful in the long-term success of the species," says Liede-Schumann.

The reduction in a variegated leaf's ability to photosynthesise is likely to be more than offset by the benefits of not being eaten, the researchers believe, suggesting that variegation survives in wild plants because it confers a selective advantage.

Based on an article by Matt Walker, Editor, Earth Newsat the BBC.

Exciting variegation breakthrough

Most of the variegated Cannas we grow are derived from mutations of the Italian Group, the two exceptions to that being Canna 'Kansas City', a Crozy Group mutation and C. 'Stuttgart', a Foliage Group mutation. The Italian Group variegated mutations are: C. 'Bengal Tiger', C. 'Durban', C. 'Phasion', C. 'Pringle Bay', C. 'Trinacria Variegata', C. 'Yellow King Humbert'. Although the Italians are almost seed sterile, a few seeds have been produced, However, there is no recorded instance of any seedlings being produced that carried the variegation trait.

Ms. Alice Harris of Karchesky Canna reports a breakthrough, having produced a Foliage Group canna that she has grown for a number of years now, and that originated from seed and has leaf variegation. The variegation has been stable in this plant for at least three years. The plant was tested for virus last summer and was given the all-clear, so this is a true variegation, and not induced by external means. The plant freely gives seed.

Alice started planting it's seeds late last summer as another experiment, and all seedlings to date have had variegation. She has just repeated the experiment, with another batch of seeds, to confirm the result.

As yet, it has not been established if the blooms are true-to-type, but that should be confirmed this summer when both batches come into flower.

It is interesting to see that the trait for variegation can be transmitted to seed-grown offspring, and this breakthrough offers some interesting future possibilities.

Alice has promised to take photographs regularly this season, and to share them with us, so that we can all join in the experience.

Click on image to visit the Karchesky web site

Variegation

As humans, part of our evolutionary heritage is to see beauty in patterns; that’s why variegated plants, with their zones of cream or white stripes on green leaves, are among the most highly prized. Though variegated plants are a relatively common sight at garden centres, occasionally gardeners may notice that a normally un-variegated plant in their garden suddenly develops variegation on one or more leaves or flowers. When confronted with this unfamiliar sight, some gardeners wonder how the heck it happened, while others wonder – some with hope, some with dread - if the change is permanent.

Beautiful Mutations

So how do plants that start their lives as normally green-leaved plants suddenly develop white stripes on the leaf margins? Strangely enough, variegation often starts off as one microscopic plant cell getting its genetic information a little mixed up and then growing and multiplying, producing a succession of cells carrying the same misinformation as the original wayward cell. It’s been estimated that something like one in every 500,000 cells produces a mutation spontaneously. Usually the mutation is lethal and the cell simply dies, but rarely the cell survives and replicates, reproducing the mutation right along with its normal characteristics. This is how variegated flowers and foliage come into being.

Not all mutations produce attractive results. The next time you shop in the produce section of your grocery store, have a look at a variety of different fruits and vegetables. If you’re lucky (or, rather, unlucky) you may find a few that look a little strange. I’ve seen navel oranges, for example, that look like half of a smaller orange has been “welded” onto a larger orange half; in other words, a round orange with a thick skin on one half of the sphere and a much thinner skin on the other half. This is the fruit equivalent of variegation on a leaf.

Variegation Vexation

Although it’s rare to find these variegations popping up in your existing, previously non-variegated garden plants, it does happen. (Plant breeders, who propagate millions of plants every year, have a much better chance of discovering spontaneous variegation.) However, even if variegation occurs on your plants, that variegation may not be stable – that is, the new colouration may last only the length of the season in which it originally appears. The following year, the plant may revert back to its original colour, sometimes Canna 'Stuttgart', above, reverts back to an all-green leaf, several shades lighter as well.

Stability of variegated plants has a lot to do with where the variegation itself originated in the plant. Mutations that originated in a specific layer of cells in the growing point have the greatest chance of producing stable offspring for years to come, but if the mutation originated outside of this layer, the chances of that mutation remaining stable are far slimmer.

Not Universally Popular

Of course, some gardeners would be relieved if a spontaneous variegation went away on its own. I find it interesting that a few gardening purists consider variegated plants to be abominations, unworthy of inclusion in the garden because they deviate from the norm, and in the Victorian and Edwardian eras that was the consensus opinion. But in reality, every single species of plant in the world owes its existence to a string of mutations that occurred over the eons. Variegation is just one more variation, and one that I feel makes gardening so rewarding.