Jack-in-the-pulpit: The Forest Floor’s Hermaphrodite

By Leah Mital-Skiff

I don’t want to make any controversial statements about whether it is easier to be male or female, but it is tempting in this case. When times are good on the forest floor, Jack turns into Jackie and when the going gets rough, Jackie turns back into Jack.  We could say that Jackie likes to cruise during the good times, but her reproductive work requires a more nutrient-rich environment.

Jack-in-the-pulpit, Arisaema triphyllum, is hermaphroditic and begins adulthood as Jack, its male expression.  After maturing past the seedling stage, the plant will produce male flowers on the spadix, the cylindrical reproductive structure commonly referred to as “Jack” and are buried deep inside the pulpit, covered by the hooded spathe.  The musty-smelling spadix attracts gnats that enter through an opening in the base of the spathe and move up and down the spadix gathering pollen from the male flowers.

If conditions were ideal the previous year, elsewhere in the forest, another jack-in-the-pulpit stored enough energy to emerge this year as a female, producing female flowers.  This growth takes a significant amount of energy and requires optimal conditions of light, nutrient availability and moisture.  Thus, Jack will only emerge the next year as Jackie if the conditions are favorable.  Jackie comes endowed with two sets of leaves in order to capture more sunlight and produce the energy she needs for reproduction.  Male plants in a stressed environment will remain in the male form into the next year.  Females under stress will revert to male and conserve energy.

Jack-in-the-pulpit is conspicuous in the early fall. The brilliant red fruits draw the eye from the changing canopy foliage in late September to the floor of eastern mixed hardwood forests.  The bright red show on an autumn day denotes its success after many potential cycles between its male and female expressions to result in the production of fruits.

Perhaps the Jacks boast that they can tough out a nutrient-poor environment and wait out the bad times. Jackie then reminds us how much more energy is needed for her role in reproduction; males have the easy job of producing pollen-bearing flowers.  In the end, the strategy of sequential hermaphrodism ensures more successful reproduction.  In a stressed environment, the jack-in-the-pulpits in the area simply do not produce seeds.  They conserve their resources and produce fewer seeds of a higher quality and viability for germination.  When we see the brilliant red among the browning leaves of the fall, the story ends in success of gender synchronicity. The male plants have browned and wilted along with the other plants of the forest floor while Jackie boasts hermaphroditic success in a show of red to beckon the birds to disperse her seeds. Jackie does steal the show in the end.