There are both male and female Jack-in-the-Pulpits, and nutrition determines which gender a given plant is. For the first year or two, every Jack-in-the-Pulpit bears male flowers. Then the amount of nutrients the plant takes up begins to influence the sex of the plant. Females flowers produce seeds, and it takes a considerable amount of nutrients to do so. Thus, if there’s an abundance of nutrients one summer, a plant is female the following summer; a lack of nutrients produces male Jack-in-the-Pulpits the following year.
While the flowers themselves are very distinct (females are green knobs, males are threadlike and not green), it can be hard to see them, as the spathe (pulpit) wraps around the spadix (Jack) which bears the flowers at its base. You can often guess the sex of a Jack-in-the-Pulpit by the number of leaves it has. In general, female plants produce two leaves, whereas male plants usually have only a single leaf. If nutrients are really lacking, the plant typically produces a single leaf, but no Jack or pulpit. (Photo: female Jack-in-the-Pulpit on the left; male Jack-in-the-Pulpit on the right).
Black vine weevil larvae overwinter in the soil. In the spring, the flightless adults emerge and feed at night on the outer edges of leaves, causing the leaves to have a notched margin. They mate and lay as many as 500 eggs in the soil near the base of host plants. The larvae hatch in a week or two and feed on plant roots until cold temperatures drive them further underground. The larval stage is quite destructive, especially to landscape plants such as rhododendron and azalea. Female black vine weevils have the ability to reproduce parthenogenetically. Fertilization of eggs is required to produce males, but no males have been observed in North America. (photo: adult black vine weevil on Jack-in-the-Pulpit fruit)
After the spathe (hood) dies back, Jack-in-the-pulpit fruit is more obvious, especially as the green berries turn brilliant reddish-orange at this time of year. Eventually the stem withers and the seed head falls to the ground. The tissues of Jack-in-the-pulpit, particularly the roots, contain high toxic levels of oxalic acid. The berries, if eaten, cause a burning sensation in the mouth and throat due to physical cuts caused by the crystals of calcium oxalate. Although cattle, goats, pigs and sheep are susceptible to the toxin, white-tailed deer, wild turkeys and wood thrushes appear to consume them without distress. As is obvious from this photograph, though, the berries are not in high demand.
When Black Bears emerge from their dens in the spring, they have lost between 15 and 40 percent of their weight, and food is in short supply. About 85% of a bear’s diet is vegetation, and most trees and shrubs have not leafed out yet. Black Bears often head to wetlands, where grasses and sedges are beginning to sprout. Nutritionally the shoots of these plants provide them with some of the protein they need, but this source of nutrients is short-lived, as the shoots are tender for only a few days before hardening with cellulose. Roots, bulbs, corms and tubers of plants such as Skunk Cabbage and Jack-in-the-Pulpit are sought after, as are the buds of trees, but bears must wait for the bountiful supply of berries and nuts that mature in summer and fall. Those bears living near humans come to rely on foods inadvertently provided by these humans, such as highly nutritional sunflower seeds being fed to birds. One can hardly blame bears for taking advantage of this available source of food during this challenging time. Feeders and cans containing seed should be put in a bear-proof location if you don’t want to encourage “nuisance” bears which, unfortunately, are sometimes killed just for trying not to starve to death.