Sunday, March 28, 2010


I took these photos last summer in the woods in the town where I grew up, Barrington Rhode Island. These unusual looking woodland flowers are actually pretty easy to find in shady areas of New England. Meet Arisaema Triphyllum, our one native species of jack-in-the-pulpit.

I used to think jack-in-the-pulpit was carnivorous. The tube-shaped structure reminded me of pitcher plants. They aren’t carnivorous and the jack-in-the-pulpit has a modified flower while the tube-shaped trap on a pitcher plant is made of modified leaves. However, I recently found out that they aren’t quite that far off.

A. triphyllum is a member of the family Araceae, an entomophilous group of flowering plants (that is they are pollinated by insects: ento = insect phil = attraction). Most of these plants are pollinated by dipterans (flies) but can either form mutualistic or antagonistic relationships with them. They all lure the flies in with the smell of their flower and some provide the flies with sites for mating and ovipositing (egg laying) while others fake it and simply take advantage of the little insects’ desire to reproduce in a safe place. This one, A. triphyllum, is a deceptive species.

The males of the species, which are slightly smaller than the females, lure the insects into the flower. The insects are then released through a small opening at the bottom after getting covered in pollen. They are then free to either find another male, picking up a different individual’s pollen, or to eventually find a female. But here’s the commonality with the pitcher: the females lack that little opening which allows the flies egress to their freedom. Usually the dipteran pollinators simply die after pollination is complete. It is unclear why exactly this is the case. It may be a step towards evolving into a carnivorous plant but this tends only to evolve in places like bogs and other areas of very poor soil nutrition. Probably it is just a random mutation that may never be utilized for any kind of real increase in the plant's fitness.

Oh yes and the best part is that jack-in-the-pulpit flowers grow from corms. You can read more about corms in my post below about crocuses.

Barriault, I., D. Barabe, L. Cloutier and M. Gibernau (2010). “Pollination ecology and reproductive success in Jack-in-the-pulpit (Arisaema triphyllum) in Quebec (Canada).” Plant Biology 12:161-171.

Read the article here.

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