It’s easy to become confused when walking in the woods and discovering two plants which have three leaves, or leaflets, and the plants look very much alike. But there’s just something a bit different about them, too. The above photo is a typical example of this situation. Both plants have leaves or leaflets with smooth (entire) margins and pointed tips.
Jack-in-the-pulpit (Arisaema triphyllum) has either one or two leaves per plant. Each leaf is compound and has three leaflets.
The Jack-in-the-pulpit leaf looks very much like Trilliums such as the White trillium (Trillium grandiflorum) which has three distinct leaves (not leaflets) at the top of the plant. The three Trillium leaves are whorled in arrangement and therefore look like the three Jack-in-the pulpit leaflets at the top of their leaf stalk.
But if neither the Jack-in-the-pulpit nor the Trillium are blooming or fruiting, then how can we tell them apart? Or what if the plant is very young and is not mature enough to flower yet?
Leaves on Trilliums have palmate veins. All the primary veins extend from the base of the leaf. It’s just like the multiple fingers extending from the palm (or base) of your hand.
The Jack-in-the-pulpit leaflets have a different venation pattern. These leaflets have a single central vein running from the base of the leaflet to the tip. The remaining primary veins extend from either side of this central vein. This is referred to as pinnate venation.
Now that you know the key to distinguishing these plants, which plant is which in the first photo of this post?
Here’s the answer: