Arisaema triphyllum

Arisaema triphyllum, the Jack-in-the-pulpit, is a species of flowering plant in the arum family Araceae. It is a member of the Arisaema triphyllum complex, a group of four or five closely related taxa in eastern North America. The specific name triphyllum means "three-leaved", a characteristic feature of the species, which is also referred to as Indian turnip, bog onion, and brown dragon.
Used without qualification, the name Arisaema triphyllum is ambiguous. For clarity, the qualified name Arisaema triphyllum sensu stricto refers to the species while Arisaema triphyllum sensu lato refers to the species complex. The latter includes the species among its members.
Arisaema triphyllum sensu lato is wide-ranging across eastern North America, from Nova Scotia to Manitoba in eastern Canada, and from Texas to Florida in the southern United States. It is common throughout most of its range.

Description

The Arisaema triphyllum complex includes four closely related species: Arisaema pusillum, Arisaema stewardsonii, Arisaema quinatum, and Arisaema triphyllum sensu stricto. A fifth species is sometimes included but its validity is controversial.
Arisaema triphyllum sensu lato is a herbaceous, perennial, flowering plant growing from a corm. It typically grows up to tall, but populations in Georgia and Florida are known to reach almost twice that height. It has 1 or 2 leaves, each with three leaflets. Occasionally the lateral leaflets will be two-parted or lobed, giving the appearance of five leaflets per leaf. One species typically has five pseudo-leaflets per leaf.
The small, inconspicuous flowers of Jack-in-the-pulpit are borne on a fleshy, spike-like inflorescence called a spadix, which is enclosed by a large, sometimes colorful bract called a spathe. The flowers are clustered around the base of the spadix inside the spathe. A sterile spadix appendix protrudes from the mouth of the spathe tube. The appendix is covered by the leafy tip of the spathe, referred to as the spathe hood. The lip along the mouth of the spathe tube, used as a landing platform for winged insects, is called the spathe flange.
The inflorescence can be male, bisexual, or female. Arisaema is quite unusual in that individuals change sex in a pattern determined by their size. In a small plant, most if not all of the flowers are male. As the plant matures and grows larger, the spadix produces female flowers as well as male flowers. The transition from male to female continues until eventually the plant produces female flowers only. This is an example of dichogamy, a rare phenomenon in flowering plants. Due to this sex-change lifecycle, this species is sometimes called colloquially as Jack or Jill in the pulpit or Jill-in-the-pulpit.
The unripe fruits are smooth, shiny green berries clustered around the thickened spadix. Fruits ripen in the late summer and early fall, turning a conspicuous bright red color. Each berry typically produces 1-5 seeds, which are white to light tan, rounded, often with flattened edges and a short sharp point at the top. If the seeds are freed from the berry, they will germinate the next spring, producing seedlings each with a single rounded leaf. A seedling needs three or more years of growth before it becomes mature enough to flower.
Arisaema pusillum, Arisaema stewardsonii, and Arisaema quinatum are diploid with 28 chromosomes. Arisaema triphyllum s.s. is predominantly tetraploid with 56 chromosomes but plants otherwise indistinguishable from typical A. triphyllum occasionally have 28 chromosomes. Two such plants were found in Cayuga County, New York in the 1940s. The evolutionary origin of the tetraploid is unknown.

Identification

The following table of characteristics serves to separate the members of the Arisaema triphyllum complex:

	Arisaema triphyllum s.s.	Arisaema pusillum	Arisaema stewardsonii	Arisaema quinatum
Leaflets, abaxial	Glaucous	Light green, glossy	Light green, glossy	Glaucous
Leaflets, lateral	Very gibbous or lobed	Slightly or moderately gibbous	Slightly gibbous	Two-parted or lobed or very gibbous
Spathe tube	Smooth to slightly fluted	Smooth to slightly fluted	Strongly fluted	Smooth
Spathe hood shape	Broad lanceolate to ovate, tip acute or acuminate	Lanceolate to ovate, tip acuminate	Ovate, tip acute	Oval to orbicular, tip abruptly apiculate
Spathe hood color, adaxial	Green with purple stripes or wholly green	Wholly purple or wholly green, rarely purple with fine green stripes	Green with purple stripes in the throat	Green
Spathe flange	Flat or slightly revolute, 4.5–7 mm wide	Revolute, 1–3 mm wide	Revolute, 1–3 mm wide	2–5 mm broad, flaring
Spadix appendix	Clavate, straight, 4–10 mm in diameter	Cylindric, straight, 2–5 mm in diameter	Cylindric, straight, 2–5 mm in diameter	Cylindric, curved outward, 1–2 mm in diameter
Somatic chromosome number	56	28	28	28
Habitat	Mesic deciduous woodlands	Hydric deciduous woodlands, swamps, wetlands	Hydric deciduous woodlands, bogs, swamps, wetlands	Mesic deciduous woodlands
Range	Wide-ranging across eastern North America	Primarily southeastern U.S.	Primarily northeastern U.S. and southeastern Canada	Endemic to southeastern U.S.

In the body of the table above, important diagnostic characters are emphasized in bold. To identify an individual to species, ask the following questions :

Is it Arisaema stewardsonii? If not, continue.
Is it Arisaema quinatum? If not, continue.
Is it Arisaema pusillum? Otherwise it is Arisaema triphyllum s.s.

Although the taxa are morphologically distinct, identification may be difficult, especially from herbarium specimens where the required characters are often lost in pressing and drying.
Non-flowering plants are sometimes confused with those of Pinellia, a genus of plants native to East Asia but introduced to a handful of states in the eastern U.S., including the District of Columbia, Maryland, New York, Pennsylvania, and West Virginia.

Taxonomy

Arisaema triphyllum sensu stricto was first described as Arum triphyllum by the Swedish botanist Carl Linnaeus in the first edition of Species Plantarum in 1753. Linnaeus expanded the description of the taxon in the second edition published in 1763. The Austrian botanist Heinrich Wilhelm Schott placed Arum triphyllum in the genus Arisaema in 1832. The name Arisaema triphyllum is widely used today despite a taxonomic disruption that prevailed during the second half of the twentieth century.
By 1903, four additional species of Arisaema in eastern North America had been described: Arisaema acuminatum, Arisaema pusillum, Arisaema quinatum, and Arisaema stewardsonii. In 1940, Merritt Lyndon Fernald posed the question "What is Arisaema triphyllum?", arguing that the type described by Linnaeus was in fact Arisaema pusillum, a claim that destabilized the existing nomenclature. In response, a proposal to conserve the name and type of Arum triphyllum was briefly considered, but in 1993 the Committee for Spermatophyta recommended against the proposal, which effectively established the name Arisaema triphyllum as the official name of the entity. However, the committee's action left botanists with an inherently unstable nomenclature.
Dismissing Fernald's claim as inconclusive, Donald Grunert Huttleston introduced three subspecies of Arisaema triphyllum in 1949, and a fourth subspecies in 1981. He discussed but rejected a fifth taxon believed to be of hybrid origin. Together with their basionyms and other synonyms, these five taxa are sometimes referred to as the Arisaema triphyllum complex:

Species	Subspecies	Varieties
Arisaema acuminatum Small		Arisaema triphyllum var. acuminatum Engl.
Arisaema pusillum Nash	Arisaema triphyllum subsp. pusillum Huttl.	Arisaema triphyllum var. pusillum Peck
Arisaema quinatum Schott Basionym: Arum quinatum Nutt.	Arisaema triphyllum subsp. quinatum Huttl.
Arisaema stewardsonii Britton	Arisaema triphyllum subsp. stewardsonii Huttl.	Arisaema triphyllum var. stewardsonii Stevens
Arisaema triphyllum Schott Basionym: Arum triphyllum L.	Arisaema triphyllum subsp. triphyllum	Arisaema triphyllum var. triphyllum

, all five taxa are recognized. Some authorities accept subspecies, while a few accept varieties. Plants of the World Online and others accept multiple species in lieu of subspecies or varieties. Still others, including the influential Flora of North America, lump all of the taxa into a single species concept.
Within the genus Arisaema, A. triphyllum is classified in the section Pedatisecta and is most closely related to Asian species such as A. amurense. It is not a close relative to the other American Arisaema species, which are in a different section of Arisaema.