Virtual Nature Trail

Scientific name: Arisaema triphyllum
Common name: 

(Information in this Species Page was compiled by Melissa “Moe” Ortz in Biology 220W, Spring 2002, at Penn State New Kensington)

Jack-in-the–Pulpit (Arisaema triphyllum) has many common names: arum, Indian turnip, wild turnip (and, “swamp,” “marsh,” “meadow,” and “dragon” turnip, too!), bog onion, brown dragon, devil’s ear, and priest’s pintle. Examining these names gives important insights into both the morphology and the ecology of the plant: it has a substantial, bulb-like root (called the “corm”) which can be eaten or used in a variety of other ways, it grows in moist habitats, and its flower is unusually and distinctively shaped and colored.

Range and Habitat
Jack-in-the-Pulpit is a long-lived perennial found in the moist, deciduous forests throughout eastern North America. Its range extends from Nova Scotia to the Gulf of Mexico and westward to Minnesota and Louisiana.  It prefers soils that are neutral to acid in pH, rich in humus and nutrients, and moist but well aerated (i.e well drained). It is most often found in forests with a diverse under-story plant community which probably reflects the preference of many other plants species for these robust, optimal site conditions. There are four described sub-species that have generalized, overlapping distributions in the northern, southern and western sections of this broad continental range.

Jack-in-the-Pulpit’s flowering form consists of a three inch long, columnar structure called the spadix on which the many, tiny, male and female flowers are located. The spadix is encased by a tubular, leaf-like structure called the spathe whose open top is partially covered by a “hood” or flap of leafy tissue. The spathe can be tinted either red or purple and often has brown or white longitudinal stripes and furrows. The hood of the spathe is usually yellow-green but may be very pale in plants growing in higher levels of sunlight. The leaves of the plant are, as the species name defines, found in groups of three leaflets that rise over the top of the spathe. Both the leaflets and the flower arise from a single stalk from the subterranean corm. This stalk, then, branches to form the spathe and the slightly longer leaf stalk. The sub-species of Jack-in-the-Pulpit vary in their spathe and spadix morphologies and colorations and in the colorations of their leaflets.

Jack-in-the-Pulpit reproduces both vegetatively and sexually. In vegetative propagation lateral buds called “cormlets” arise from the parental corm to form new plants. In sexual reproduction pollen from male flowers is transferred to female flowers by a variety of pollinating insects (including collembola, and several species of flies and thrips). The encasing spathe, of course, prevents any wind dispersal of pollen. Male flowers are found in the upper sections of the spadix and female flowers in the lower. In a given plant either male or female flowers predominate. A phenomenon called sequential hermaphroditism (discussed below) coupled with the temporal asynchrony of male and female flower maturation act to inhibit or prevent self-fertilization. In male flowers, a fine dusting of pink pollen accumulates at the bottom of the volume of the spathe.

Fruit of Jack-in-the-PulpitAfter pollination, the spathe dies back revealing a cluster of green, berry-like fruit attached to the stalk of the spadix. These fruit turn bright red as they ripen on into the autumn. Each fruit contains a maximum of six ovules, but, on average, only one or two seeds. Not all plants produce seeded fruit. Less than half of the plants in one study were actually found to have fruit that contained seeds and of these seeded fruit over one-third were shriveled and unviable. Speculative explanations for this high level of reproductive failure include low numbers of pollinating insects, pollen-ovum incompatibility, and site nutrient limitations.

Life Cycle and Sequential Hermaphroditism
Jack-in-the-Pulpit displays a distinctive cycle of growth and development in which not only the age of the plant but also the conditions and limitations of its environment determine its relative gender and also its potential fertility. A seedling growing either from a fertilized seed or from a vegetative cormlet will spend from four to six years in a pre-reproductive, vegetative form. As sufficient size is reached after these immature, growth years, the first flowers produced will be male, pollen producing flowers. As the plant continues to grow, though, through subsequent years the larger and larger spadix will begin to produce female flowers and thus then be able to produce seeds and fruit. Increases in nutrient availability or habitat quality will accelerate the transition of male plants into female plants. Decreases, though, in nutrients or habitat quality, or impacting environmental stresses, will cause female plants to revert back to their earlier male form or even back into their pre-flowering, vegetative state. This extremely plastic flowering cycle (called sequential hermaphroditism) ensures that only plants of sufficient size and physiological and genetic quality are capable of reproduction. It also prevents energetically expensive reproduction during times of nutrient deprivation or environmental distress.

The corm of the plant is perennial and very long lived. After a period of winter dormancy (which is broken by a month of at least four degrees C), it extends a new shoot which branches to form spathe and leaflets in the spring and early summer.

Ecological Impact
Jack-in-the-Pulpit contains toxic levels of oxalic acid and asparagines within its tissues. The roots, in particular, have very high levels of these chemicals. The berries, if ingested, cause a burning sensation in the mouth and throat due to physical abrasions in the mucous membranes caused by crystals of calcium oxalate. In spite of these toxins, though, deer potentially do heavily browse Jack-in-the-Pulpit causing extensive damage and destruction. Also, a fungal pathogen (Uromyces aritriphylli) frequently infects the plant causing damage to the corm, the leaflets, and the spathe. An infected plant is easily identified by the presence of bright yellow, spore producing, surface lesions. Impacts of this fungus include reduced growth of the plant and potential flower stage regression, reduced vegetative propagation, and inhibited pollination due to deformations in the spathe and its covering hood. In a given population of Jack-in-the-Pulpit a fourth of the individuals are infected by this fungus. Of the infected female plants, the vast majority are no longer able to produce seeds.

Human use and ingestion of Jack-in-the-Pulpit either takes advantage of the potential medicinal applications of the plant’s toxins (such as use as skin ointments, poultices, or tonics) or follows steps by which these toxins are removed from the plant tissues (drying, roasting, leaching etc). The root, in particular, can be peeled, ground, dried and roasted to make a bread or cereal that has a chocolate-like flavor. The root can also be thinly sliced into chips that are then roasted into edible, chocolate flavored wafers.

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This page was last updated on January 05, 2006  

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