Wilting flowers do not necessarily indicate that a plant is unhealthy; instead, they might reflect an intricate resource management strategy that plants have developed over millions of years.
A recent article in the journal Plant Biology, authored by researchers from Macquarie University along with international collaborators, reveals for the first time that plants can repurpose resources from their wilting flowers to aid in future reproduction.
Honorary Professor Graham Pyke, the lead author from Macquarie University, explains that these findings shed light on a common yet often misunderstood process in plants. The research provides insights into how plants efficiently utilize their resources.The initial clear proof that plants can recover resources from dying flowers and use them again to enhance future reproduction comes from Professor Pyke. These resources consist of the energy and chemical components found in the petals, such as carbohydrates, along with essential nutrients like nitrogen and phosphorus.
Conducting the Research
The research, which lasted three years, centered around Blandfordia grandiflora, also referred to as Christmas Bells, which predominantly blooms in December. This perennial plant species features vibrant red and yellow flowers and is native to eastern Australia. It is frequently available for sale in flower markets across Australia and internationally.
Commercially cultivated Christmas Bells can produce anywhere from two or three flowers up to more than a dozen.
“Our study is conducted on a plantation that spans several hectares of native wet heath, where Christmas Bells bloom abundantly, alongside a commercial shadehouse,” explains Professor Pyke.
The research team employed various methods to manage pollination and flower wilting, then observed the impacts on seed production and the plants’ ability to flower again.
Unexpectedly, the researchers discovered that these plants did not allocate resources from wilted flowers to enhance their short-term reproductive success.
“These plants make the most of their reproductive resources from one flowering period to the next,” explains Professor Pyke.
Blandfordia grandiflora, for instance, collects nutrients from its fading flowers and stores this ‘chemical energy’ in its underground corms and roots. This stored energy supports the growth of new flowering stems in the following season, usually a year later.
Plant Economics
According to Professor Pyke, the plant kingdom showcases intriguing strategies for resource management and economic principles.
“The economics of plants revolve around making choices,” he explains. “Plants have to decide how to distribute their limited resources; if they focus on one area, it means less investment in another.”
This idea of managing resources is what prompted Professor Pyke to explore why flowers wilt. For years, scientists have wondered if this behavior helps plants divert precious resources to other functions.
“We were caught off guard,” says Professor Pyke. “It appears that the plants were strategizing over a longer period than we had expected, holding onto their recovered resources for future use instead of using them right away.”
During their flowering period, plants exhibit various strategies for handling their blossoms after they have fulfilled their main role in reproduction, and wilting is just one among several options.
However, not all plants adhere to the pattern of wilting flowers; certain species continue to bloom long after fertilization is impossible and nectar production has ceased.
“Flowers enhance the plant’s appeal to pollinators even when they are merely part of the overall aesthetic,” he explains.
Some species will shed their flowers prematurely instead of waiting to wilt. For instance, jacaranda flowers that appear perfect often drop off before wilting occurs.
When frangipani trees bloom, their flowers typically fall to the ground without wilting. In some cases, these trees may drop fully intact flowers instead of allowing them to wilt.
Exploring Theories
The research investigated the reuse of resources through various experiments.
One specific test looked at the difference in seed production between plants that were allowed to let their flowers wilt and those that had their petals removed to stop wilting. Another test halted seed production for all plants but permitted one group to wilt.
“It’s straightforward to stop seed production by cutting off the stigma,” explains Professor Pyke.
The findings indicated that plants with wilting flowers had a higher likelihood of blooming again in the following season compared to others.
The research also examined additional elements that could affect seed output, including the height of flowering stems, the quantity of flowers on each stem, and where the flowers are located on the plant.
For instance, taller stems with more flowers yielded a greater amount of seeds and heavier seeds. Conversely, flowers that were situated lower on the plant generally produced fewer seeds and those seeds tended to be lighter in weight.
“Our results open up new avenues for investigating other plant species and their ability to recuperate and utilize resources from wilting blooms,” states Professor Pyke.
Future studies might look into how these reclaimed resources contribute to overall plant health and reproduction.
