Variation in swamp rose mallow flowers

Posted by Richard B. Primack

Simplicity is the law of Nature for man as well as for flowers. 

Henry David Thoreau

Rose mallow (Hibiscus moscheutos) is a spectacular wildflower, with multi-stemmed plants growing 6 feet tall and covered with dessert-plate sized flowers.  Large populations grow along the banks of the Charles Rivers, with over a thousand plants at one notable location. 

Rose mallow plants growing along the Charles River.

While most plants have pink flowers, other plants produce flowers that are light pink, very light pink, or even white.  In addition, some plants produce flowers with a red center, and other plants produce flowers without the red center.  Plants also vary in the size of the flowers, and whether the petals are bent strongly forward or slightly forward, or flared out at a right angle.

Three plants growing next to each other: on the left a plant with white flowers with a red center; in the middle a plant with light pink flowers with a red center; and on the right a plant with pink flowers and no red center. 

This striking floral variation is almost certainly genetic, as all of the flowers on a plant will share the same characteristics of color, presence or absence of the red center, flower size, and petal orientation.

A plant with white flowers and red center, growing next to a plant with pink flowers and a red center. 

There is also variation in leaf color with some plants producing bronze colored leaves.

White flowers with no red center. 

This species seems tailor made for studies of pollination ecology, genetics, and evolution.