Solanum diphyllum, commonly known as the twoleaf nightshade,[1] is a species of nightshade native to the Americas. It is cultivated as an ornamental plant for its clusters of dark green round fruits that turn a bright yellow when ripe.

Twoleaf nightshade
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Solanales
Family: Solanaceae
Genus: Solanum
S. diphyllum
Binomial name
Solanum diphyllum
Distribution of S. diphyllum. Native range is in green. Areas under which it had been naturalized or are widely cultivated are in orange.

Taxonomy edit

Unripe berries and a leaf pair (major and minor leaf) relative to a human hand.
The inflorescence and fruits of twoleaf nightshades are borne opposite of the leaf pairs.

Twoleaf nightshade is classified under the subgenus Minon. It belongs to the tribe Solaneae, subfamily Solanoideae, under the very large and diverse nightshade family (Solanaceae). It was first described by Carl Linnaeus in his 1753 book Species Plantarum.[2]

The forest nightshade (Solanum nudum), another species altogether, was originally illegitimately named Solanum diphyllum by the Spanish botanists Martín Sessé y Lacasta and José Mariano Mociño in 1894, despite the name already being used.[3]

Twoleaf nightshade may sometimes be confused with the Jerusalem cherry (Solanum pseudocapsicum), another nightshade grown for its brightly colored berries, and referred to by various synonyms, some of which were once classified as its cultivars. Within the genus, it most closely resembles a rare species in western Mexico, Solanum malacothrix.[4]

Twoleaf nightshade is also known as twinleaf nightshade, twin-leaved nightshade, two-leaf nightshade, and other variations of the name. The specific epithet 'diphyllum' means "two leaf", referring to the arrangement of its leaves. It is sometimes called by other names such as tomatillo (not to be confused with the edible Physalis philadelphica), amatillo, and 黄果龙葵 (Huang guo long kui).[4][5][6]

Description edit

Ripe and unripe berries of twoleaf nightshades.

Twoleaf nightshade grows as a small shrub about 1 to 2 m (3.3 to 6.6 ft) tall. The stems are smooth or sometimes slightly downy with a dark brown bark.[4]

A distinctive feature of twoleaf nightshade is that its leaves grow in pairs from a single bud, hence the name 'twoleaf'. Each pair is composed of a major and a minor leaf. Major leaves average around 6 cm (2.4 in) long by 2 cm (0.79 in) wide and are elliptic to oblong in shape. Minor leaves are smaller and more rounded; they are 2 cm (0.79 in) long by 1 cm (0.39 in) wide on average.[6] The leaves are a glossy dark green on the upper surface with a lighter green on the ventral side. The petioles are about 2 mm (0.079 in) in length.[4]

The inflorescences are borne opposite the leaves. Each bears about 5 to 20 closely spaced flowers. The flower buds are white and globular when young but become more lavender in color and elongated as they mature. They bloom into tiny white flowers with a lavender tinge about 1 cm (0.39 in) across.[4]

The fruits are spherical berries with a slight division around the middle, especially when unripe. They are green and hard when young, around 1 cm (0.39 in) in diameter. They mature into bright yellow to orange fleshy and juicy berries about 1.2 cm (0.47 in) in diameter. They are mounted on the flower calyces on long and thin pedicels. Each berry contains numerous seeds.[4]

The seeds are flattened and kidney-shaped (resembling bell pepper seeds), each about 3 mm (0.12 in) long and 2.5 mm (0.098 in) wide. They have pale margins and are minutely pitted.[4]

Distribution and habitat edit

Twoleaf nightshade is native to Northern and Central America in Mexico, Belize, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua.[2] It is widely cultivated as an ornamental plant in subtropical and tropical parts of the world like Southern France, Italy, and Taiwan.[4][6] It has escaped cultivation in some areas and become naturalized in Florida and Texas, United States;[5] Java, Indonesia; the Philippines; and the West Indies.[7][8]

Twoleaf nightshade is a ruderal species, colonizing newly disturbed lands.[9] It also grows in mangrove forests.[10]

Ecology and cultivation edit

Twoleaf nightshade is grown for its attractive clusters of green and yellow berries. The plants are spread very easily. Fruits are eaten by birds and bats, both of which help disperse the seeds. The seeds are especially hardy, able to survive being buried in an inch of soil for up to two years. Seventy five to eighty five percent of the seeds will sprout.[5]

The plant is poisonous to humans.[5]

Methods of controlling it in areas where it is unwanted mostly involve being familiar with its growing habits and appearance and uprooting the plants before they bear fruits.[5]

Phylogeny edit

Twoleaf nightshade belongs to the Geminata clade, section Holophylla, along with Solanum pseudocapsicum and Solanum pseudoquina.[11]

See also edit

References edit

  1. ^ USDA, NRCS (n.d.). "Solanum diphyllum". The PLANTS Database ( Greensboro, North Carolina: National Plant Data Team. Retrieved 17 November 2015.
  2. ^ a b "Solanum diphyllum L." Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved May 15, 2011.
  3. ^ Sandra Knapp (2008). "Typification of Solanum (Solanaceae) species described by Martín de Sessé y Lacasta and José Mariano Mociño" (PDF). Anales del Jardín Botánico de Madrid (in English and Spanish). Consejo Superior de Investigaciones Científicas. 65 (1): 7–23. doi:10.3989/ajbm.2008.v65.i1.243. ISSN 0211-1322. Retrieved May 15, 2011.
  4. ^ a b c d e f g h Sandra Knapp (2004). "Solanum diphyllum L., Sp. Pl. 184. 1753. Type: America?, Anon. s.n. (lectotype, LINN 248.5, designated by Knapp & Jarvis, 1991)". Solanaceae Source, Natural History Museum. Retrieved May 15, 2011.
  5. ^ a b c d e Dan Culbert (October 2, 2005). "The Weed with Two Leaves". IFAS Extension, University of Florida. Retrieved May 16, 2011.
  6. ^ a b c Zhang Zhi-yun; Lu An-ming & William G. D'Arcy (1994). "Solanaceae (茄科)" (PDF). Flora of China (中国植物志). Science Press & Missouri Botanical Garden. 17: 300–332. Archived from the original (PDF) on July 14, 2009. Retrieved May 16, 2011.
  7. ^ Sandra Knapp (2009). "Synopsis and lectotypification of Solanum (Solanaceae) species endemic in the West Indies". Anales del Jardín Botánico de Madrid (in English and Spanish). Consejo Superior de Investigaciones Científicas. 66 (1): 65–84. doi:10.3989/ajbm.2209. ISSN 0211-1322. Retrieved May 16, 2011.
  8. ^ USDA, NRCS (n.d.). "Solanum diphyllum". The PLANTS Database ( Greensboro, North Carolina: National Plant Data Team.
  9. ^ Ed Weislo. "Invasive Exotic Plants in Florida". Florida's Nature. Retrieved May 16, 2011.
  10. ^ Carmen Teresa Cuevas-Arias; Ofelia Vargas & Aarón Rodríguez (2008). "Solanaceae diversity in the state of Jalisco, Mexico (Diversidad de la familia Solanaceae en el estado de Jalsico, México)" (PDF). Revista Mexicana de Biodiversidad (in English and Spanish). Instituto de Biología. 79: 67–79. ISSN 1870-3453. Retrieved May 16, 2011.
  11. ^ "Solanum phylogeny". Solanaceae Source, Natural History Museum. 2004. Retrieved May 15, 2011.

External links edit

  Media related to Solanum diphyllum at Wikimedia Commons   Data related to Solanum diphyllum at Wikispecies