Arisaema triphyllum (L.) Schott



CC = 6
CW = -3
MOC = 75

© SRTurner

Family - Araceae

Habit - Perennial monoecious forb from a corm.

Stem - Ascending to erect, to 20 cm, glabrous.

Arisaema_triphyllum_stem.jpg Stem and nodes.

© SRTurner

Leaves - Alternate, usually 2 per aerial stem, trifoliate. Petioles 30-60 cm, glabrous, the bases sheathing the stem. Leaflets 3, asymmetrically arranged on petiole, glabrous, the largest leaflets to 20 cm long, elliptic to ovate, the lateral leaflets usually asymmetrical. Leaflet lateral venation typically closed in loops, not reaching the leaflet margin.

Arisaema_triphyllum_leaf.jpg Leaf.

© SRTurner

Arisaema_triphyllum_diagram.jpg The right angled "T" arrangement of the three leaflets is highly characteristic of this species, and makes for easy identification even when the plants are not blooming.

© SRTurner

Arisaema_triphyllum_leaflet1.jpg Leaflet adaxial.

© SRTurner

Arisaema_triphyllum_leaflet2.jpg Leaflet abaxial.

© SRTurner

Arisaema_triphyllum_petiole.jpg Petiole and leaflet bases.

© SRTurner

Inflorescence - Peduncles shorter than petioles. Spathes 10-25 cm long, green, usually with white and dark reddish brown longitudinal markings, the base forming a loose, cylindrical sheath (the "pulpit") around the spadix ("Jack"), the apical half flattened, expanded, and arched over the spadix. Spadices cylindrical, with a blunt sterile tip extending just above the rim of the sheathing portion of the spathe.

Arisaema_triphyllum_inflorescence.jpg Inflorescence.

© SRTurner

Arisaema_triphyllum_inflorescence2.jpg Inflorescence.

© SRTurner

Flowers - Minute, numerous, arranged on spadix with staminate flowers above pistillate, or sometimes spadix with entirely staminate or pistillate flowers.

Fruits - Dense cylindric cluster of berries, these 1 cm in diameter, red at maturity.

Arisaema_triphyllum_fruits1.jpg Young fruit cluster (with withered remains of spathe). These will turn bright red at maturity.

© SRTurner

Flowering - April - June.

Habitat - Rich bottomlands, mesic forests, and bluff bases.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - This is a species which, when in flower, is instantly recognizable and impossible to mistake for anything else. The "Jack in the Pulpit" structure is not a flower but rather an entire inflorescence. The actual flowers are minute and hidden down in the "pulpit" around "Jack's" shins. This delightful plant is found throughout Missouri, and also across the eastern half of the continental U.S. Its westward extent ends rather abruptly at around the longitude of eastern Kansas and Nebraska. The plant is even easy to identify from the leaves alone, which have their broadly ovate leaflets arranged in a characteristic T-shape. The entire plant can range greatly in size, with large specimens growing waist-high and bearing leaflets a half meter across. The color of the spathe ("pulpit") can vary considerably and has been used to assign infraspecific forms, though these intergrade freely.

Missouri plants are assignable to ssp. triphyllum. Two or three other less common subspecies occur to the east and north of Missouri. The plants contain oxalates which render them somewhat toxic, though they can be made edible by boiling. Dried corms were ground into flour by native tribes.

Photographs taken at Engelmann Woods Natural Area, Franklin County, MO, 4-18-2011 and 4-29-2019, St. Francois State Park, St. Francois County, MO, 5-4-2014, Washington State Park, Washington County, MO, 4-21-2015, near St. Albans, Franklin County, MO, 4-28-2015, Babler State Park, St. Louis County, MO, 4-24-2020, and near Greer Springs, Oregon County, MO, 6-15-2023 (SRTurner).