Jack-in-the-Pulpit

Arisaema triphyllum Araceae/Arum/Aroid Family including Skunk Cabbage (see species post), Wild Calla, Golden Club, and tropical arums (see Araceae post).

A friend gave me one of these plants (from many) growing in the damp areas of her yard. The illustrations are from my sketchbooks.

Anastomosing veins along the leaflet borders (see below)

Underground: I don’t often see the underground parts of plants I choose to draw because I don’t want to pick them. I was delighted when my friend helped me dig up my gift and let me see what was happening beneath the ground. Below left: The corm at the top of her trowel was surrounded by deciduous contractile roots. A corm is an underground storage organ at the base of the stem which is why a clone of this perennial will bloom next year. A new corm is formed on top of the old corm and the roots will contract to pull the plant back down into the soil.

Shoots (Stems and Leaves): The leaves emerge from protective sheaths that look like snake skins. Their shapes are from another world.

First the leaves and then the spathes.

Leaves: each trifoliate leaf is a compound leaf with 3 leaflets arranged so that two of the leaflets form a straight line and the third is perpendicular to that line. Note the poison ivy leaf (below right), I photographed on the same day, has the same arrangement. There is one large tooth on the margins of the lower leaves to distinguish it (among other things) but still something to notice. Pinnate veins that extend out from a mid vein loop around forming a border along the margins or edges. This is called anastomosing, seen better in my first picture, and helps identify this leaf.

Flower. This unusual flower is an inflorescence or a cluster of separate, stalkless florets attached to the lower part of a rounded fleshy axis (spadix). That’s Jack. The florets are protected by a spathe (the Pulpit) that wraps around and overhangs Jack.

A female Jack with no space at the bottom of the spathe. (See below)

The spathe (above) has various colors and patterns that some use to describe a few sub-species. A. triphyllum ssp.triphyllum is the one most common; A. triphyllum ssp.pusillum has a solid colored spathe (maybe the middle image?); and A. triphyllum ssp.stewardsonii has a ridged or fluted spathe that I haven’t seen. These will be fun to (try and) find next year and make me look closer.

The flowers are dioecious. The male and female clusters are on different plants. But… an individual plant can change sex in the next season depending on the amount of carbohydrates manufactured and stored in its corm. Females take more energy to reproduce, are larger, and have two leaves. The males are much smaller and have only one leaf. If a female plant had a tough year and couldn’t create enough stored resources for next year, she might revert to a he.

Below: onepetiole (leaf stalk) and peduncle (flower stalk) of a male plant.

Jack leaves1
A male Jack-in-the-Pulpit.

Below: one of my favorite photos I found after learning about male and female Jacks. The larger female (left) has two leaves and a much smaller male (right) has only one leaf.

Large female Jack (left) with two compound leaves beside the smaller male (right) with one leaf.

Below: The male flower has a tiny opening at the bottom of the spathe, blocked in a female flower, so it will trap the pollen. When I enlarged my photo, I saw a little space (red arrow) at the bottom of the male flower. Fungus gnats, attracted by a fungal smell, lay their eggs in these plants thinking the larvae will have something to eat. When they find they have made a mistake, they are trapped in the female plant so they can spread pollen on the stigmas. But they can escape through the tiny hole in the male plant and maybe carry pollen to another female Jack. From: Wild Flowers of the NE, by Carol Gracie.

Right: The male flowers only have stamens and don’t need sepals and petals. I didn’t see a female flower. By the time I knew to look it had already formed fruit.

Fruit: The spathe and leaves wither as the fleshy berries develop, turn green and finally red when ripe.

3 thoughts on “Jack-in-the-Pulpit”

  1. Carol, This is great information. Wonderful and accurate drawings and such attention to detail. It is a very comprehensive account of the the plant.

    Like

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