Arisaema – Jack AND Jill in the Pulpit
By Jim Hole
Most of us are familiar with the basics of plant sexuality: bees (or other insects) spread pollen from flower to flower as they forage for food. The fertilized flower produces seeds, which grow into new plants. But not all plants follow this simple pattern; Arisaema, also known as Jack in the Pulpit, in particular, definitely pursues an alternative lifestyle.
A Popular Perennial
The genus Arisaema consists of about 150 species, with an extraordinarily wide geographic range, extending from Africa through southeast and central Asia, the Himalayas and North America. A few species are hardy on the Prairies, provided they are in a woodland setting complete with rich, leafy soil and shade.
Arisaema has long fascinated gardeners, particularly perennial enthusiasts. As the common name implies, the flower, with a bit of imagination, looks like a person standing in a church pulpit. Arisaemas are worth growing for their unusual flowers, but they are all the more interesting for their remarkable sex lives.
Alternative Life Cycles
Most plants are monoecious, producing male and female flowers on the same plant. However, there are many dioecious plants, plants that actually have separate genders, such as hops, holly and ash trees. Flowers that are, botanically speaking, “perfect” are in fact bisexual; that is, each flower contains both male and female structures within the same flower.
Arisaemas on the other hand, are neither monoecious nor dioecious; they are paradioecious. They could be called the transsexuals of the garden, because they change their gender as the situation requires.
Young arisaemas (or older arisaemas that lack vigour for whatever reason) are generally male, while well-fed, strong adult plants are typically female or bisexual; in effect, as the plant matures, Jack in the Pulpit becomes Jill in the Pulpit.
But this isn’t the only sex change arisaema can undergo. It’s fairly common for the plant to switch to producing only male flowers after the female flowers bear fruit; doing so takes less energy, and allows the plant to regain some strength. Seed production requires a lot more plant resources than pollen production, so flip-flopping between genders ensures there is enough energy to expend on seed production when resources are plentiful, yet conserves energy when such resources are lean.
Jack or Jill?
In the botanical world, a little gender-bending can give certain plants a competitive edge. In nature, when it comes to survival, nothing is certain; gender is just another tool that can be manipulated to ensure the survival of the species.