Some flowers have learned to bounce back after injury

April 07, 2020

Some flowers have a remarkable and previously unknown ability to bounce back after injury, according to a new study.

Some injured flowers bent and twisted themselves back into the best possible position to ensure successful reproduction within 10-48 hours of being knocked over, for example, by falling branches or being walked on.

The reproduction of many flowers (and survival of populations) depends on the perfect alignment of their sexual organs and nectar tubes in order for a visiting insect to pollinate them.

But some are better at recovering their alignment after an injury than others.

Professor of Ecology and Evolution Scott Armbruster, at the University of Portsmouth, published his findings in New Phytologist.

He said: "Mechanical accidents happen to plants fairly often and can, in some cases, stop the plant from being able to attract pollinating insects and so, make seeds. Making seeds and propagating is a flower's main purpose, so injuries which threaten that pose a huge problem."

The study found that bilaterally symmetrical flowers - those in which the left and right sides mirror each other, such as snapdragon, orchid, and sweet pea - can almost always restore their 'correct' orientation by moving individual flower stems or even moving the stalk that supports a cluster of flowers.

In some cases, bilaterally symmetrical flowers can accurately re-position their stigma - a sexual organ - after injury.

Plants' movement after an injury isn't only about making seeds; these plants were seen to bend or twist to make sure their leaves were again facing the Sun, necessary for photosynthesis, the process by which a plant produces its food.

Radially symmetrical flowers, star-shaped flowers, such as petunia, buttercup, and wild rose - lacked this ability and their stems rarely recovered after an injury.

Nearly all (95 per cent) of bilaterally symmetrical flowers examined moved after injury to restore the plant's ability to attract pollinators, while just four per cent of radially symmetrical flowers examined had moved post-injury. This is probably because floral orientation is usually more important for the efficient pollination of bilaterally symmetrical flowers than radially symmetrical ones.

"This little-known aspect of plant evolution is fascinating and tells us much more than we previously knew about how plants behaviourally adapt to changes in their environment, including mechanical accidents," Professor Armbruster said.

Professor Armbruster and his collaborator Nathan Muchhala (University of Missouri, St. Louis) studied 23 native and cultivated flower species in Australia, South America, North America and the UK.

They found four mechanisms involved, sometimes separately, sometimes all at once, in an injured flower reorienting itself:The younger the plant part, the faster it managed to bend, meaning stalks supporting individual flowers at the end of a cluster were more easily moved, than the stronger and older stalks supporting an entire cluster.

"Because the outlook is grave for plant species which don't allow pollinating insects in or which have lost the connection between nectar and its sexual organs, we expected plants might have found a way around this, if, for example, they are hit by high winds or falling branches," Professor Armbruster said.

"What we found, in a haphazard sample of plants, was that bilaterally symmetrical flowers were able to use up to four methods of restoring their chances of being pollinated almost to pre-injury levels.

"This ability is, I'd argue, an under-appreciated behaviour worthy of closer scrutiny."

1. Time lapse triptych - showing reorientation of rosebay willowherb flower (Chamerion angustifolium) at time of injury, then plus 5 hours, and plus 24 hours:

a) Time 0 - flowers and flower parts knocked 90 degrees out of alignment by research team
b) Time +5 hours - the flower's style (the long stalk that connects the stigma and the ovary) has moved
c) Time +24 hours - the style (but not petals) now in correct position again, the flower's stigma (the sticky platform at the end of the style where pollen is deposited) is open and receptive

2. A radially symmetrical lily flower

3. A bilaterally symmetrical orchid flower

University of Portsmouth

Related Plants Articles from Brightsurf:

When plants attack: parasitic plants use ethylene as a host invasion signal
Researchers from Nara Institute of Science and Technology have found that parasitic plants use the plant hormone ethylene as a signal to invade host plants.

210 scientists highlight state of plants and fungi in Plants, People, Planet special issue
The Special Issue, 'Protecting and sustainably using the world's plants and fungi', brings together the research - from 210 scientists across 42 countries - behind the 2020 State of the World's Plants and Fungi report, also released today by the Royal Botanic Gardens, Kew.

New light for plants
Scientists from ITMO in collaboration with their colleagues from Tomsk Polytechnic University came up with an idea to create light sources from ceramics with the addition of chrome: the light from such lamps offers not just red but also infrared (IR) light, which is expected to have a positive effect on plants' growth.

How do plants forget?
The study now published in Nature Cell Biology reveals more information on the capacity of plants, identified as 'epigenetic memory,' which allows recording important information to, for example, remember prolonged cold in the winter to ensure they flower at the right time during the spring.

The revolt of the plants: The arctic melts when plants stop breathing
A joint research team from POSTECH and the University of Zurich identifies a physiologic mechanism in vegetation as cause for Artic warming.

How plants forget
New work published in Nature Cell Biology from an international team led by Dr.

Ordering in? Plants are way ahead of you
Dissolved carbon in soil can quench plants' ability to communicate with soil microbes, allowing plants to fine-tune their relationships with symbionts.

When good plants go bad
Conventional wisdom suggests that only introduced species can be considered invasive and that indigenous plant life cannot be classified as such because they belong within their native range.

How plants handle stress
Plants get stressed too. Drought or too much salt disrupt their physiology.

Can plants tell us something about longevity?
The oldest living organism on Earth is a plant, Methuselah a bristlecone pine (Pinus longaeva) (pictured below) that is over 5,000 years old.

Read More: Plants News and Plants Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to