Plant Activity on Kiawah — Morning and Night
Story and photographs by Jane Ellis
Yes , plants can tell time ! They have circadian rhythms ( 24-hour cycles of activity ) just like the rest of us . Of course , these activities often depend on environmental clues such as light , dark , and temperature . Flowering in certain plants is a response to the length of daylight — it ’ s actually a response to the length of the dark period not light ! Some plants only bloom when the amount of light per day exceeds a species specific length of time such as 12 or 14 hours . These we call long-day ( short-night ) plants .
Here on Kiawah some of these might be the early summer bloomers . Others , such as some of our goldenrods , camphorweed , grasses , and morning glories are short-day plants and bloom when the days begin to shorten in the late summer and early fall . Still other plants are day neutral and can bloom all summer long like the beach plants , sea rocket , and silver-leaf croton . What about the ones whose blooms open and close at different times of the day and night ? Below are a few interesting examples found on our beautiful Island .
Flowers of the Morning Magnolias : Thought to be some of the most ancient flowering plants , magnolias have a unique flowering sequence . The flowers open early in the morning on the first day with the female stigmas receptive to the male pollen , but the flower ’ s own pollen is not mature . These flowers give off a lovely fragrance , and the stigma produces an exudate loaded with sugars ready for any insect to dine upon .
Most researchers believe that beetles are the main pollinators of magnolias although some conclude that different species of bees have taken over this spot . The flowers close that first night , forming floral chambers where beetles may mate , find food ( sometimes eating flower parts ), enjoy protection and warmth , and in the process pollinate the flowers . The next morning the flower reopens , and the male stamens are ready to shed an abundance of mature pollen , but the flower ’ s own female stigmas are no longer receptive .
A researcher determined that one magnolia flower could produce approximately 58 million pollen grains , and this pollen falls into the cup-shaped petals . Flowers remain open for several days , so the beetles and other insects gather pollen then head to other flowers that may be just opening on their first day . This process increases chances of cross-pollination with other magnolias . Amazing timing !
18