Jack-in-the-Pulpit: a Sequential Hermaphrodite

It’s May, wildflower season in Wild Philly, and one of the easiest to recognize spring wildflowers is Jack-in-the-pulpit, that tall, slender flower with a highly variable striped “pulpit” surrounding the long slender “Jack,” the minister standing to offer a sermon on the forest floor. It’s a cousin of the skunk cabbage, with the same arrangement: a hoodlike and striped “spathe” covering a fleshy inflorescence, the “spadix.” Reverend Jack is clothed not in robes, but in flowers.

The flower is a sequential hermaphrodite, a mature Jack first producing one sex of flowers, male flowers higher up the spadix, and then the other, females lower down, a clever way of preventing self-pollination. But younger, smaller Jacks only produce male flowers; only older plants possess the resources to produce female flowers. 

While the hooded spathe is often striped purple-brown and green, the brown varies in intensity and color, and sometimes it is simply striped in lighter and darker greens. Just like its cousin, also highlighted in this section, the flower is not trying to attract the attention of bees and butterflies. Hardly.

This is where it gets weird. Its pollinators are fungus gnats, tiny flies that lay their eggs on mushrooms, food for their larvae. The flower emits a smell like fungus, which pulls the gnats into the pulpit. The gnats bounce around inside the hood looking for mushrooms, but cannot get out, as a roof covers the opening, they cannot fly straight up, and the sides of the hood are slippery. As it continues to fall into the bottom of the spathe, it gets coated in more and more pollen-- and eventually discovers a small exit hole at the spathe's bottom. 

But a Jack with female flowers does not have that exit hole: the gnat bounces around, stuck inside, perishing in the pulpit, an extreme and unusual strategy for ensuring your flowers are pollinated.

Once pollinated, the flower produces bright red-berries that are eaten by a wide number of forest dwellers, including and especially turkeys and wood thrushes.

You should be able to find Jack sermonizing on just about any forest floor in Wild Philly, from Carpenter’s Woods in Mt. Airy, where it is happily abundant, to New Hope’s amazing Bowman's Hill Wildflower Preserve. Check it out.