Solanum rostratum
(prickly nightshade)

Preferred Common Name

• prickly nightshade

Other Scientific Names

• Solanum cornutum auct., non Lam.
• Solanum heterandrum Pursh

International Common Names

• English: beaked nightshade; beaked sandbur; buffalo berry; buffalo bitter apple; buffalo bur; buffalobur (USA); hedgehog bush; horned nightshade; horse nettle; kansas thistle (USA); pincushion nightshade; sandbur; spiny nightshade
• Spanish: abrojo (Honduras); durazillo (Honduras); guizazo de bufalo; mala mujer (Honduras)

Local Common Names

• Germany: Nachtschade, Stachel-; Stachel-Nachtschatten
• Mexico: acayocahuitle; ayohuistle; churuni; duraznillo; hierba del gato; hierba del sapo; huiztecuatl; ixpa-halkan; mala mujer; quiebra plato; rabo de iguana; vaquerillo
• Netherlands: nachtschade, stekel
• South Africa: bitterappel; buffelbitterappel; doringappel; ystervarkbos
• Sweden: taggborre

EPPO code

• SOLCU (Solanum cornutum)
• SOLRS (Solanum rostratum)

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Solanales
•                         Family: Solanaceae
•                             Genus: Solanum
•                                 Species: Solanum rostratum

Solanaceae, the Nightshade family, consists of 90 genera and 3000-4000 species with great variation in habit and distribution on all continents except Antarctica, with the majority of species diversity in Central and South America (PBI Solanum Project, 2014).

Solanum is one of the largest genera of vascular plants with 1000-1500 species, around 1000 of which are speculated to be of American origin (Hunziker, 1979). Taxonomy of the genus and its seven subgenera have undergone many revisions, but the overall genus consists of herbs, shrubs, trees, or herbaceous or woody vines, usually with spines or prickles, glabrous or pubescent with simple or stellate hairs (Acevedo-Rodriguez, 1996). The Solanum genus includes the wild potato, S. tuberosum, the tomato, S. lycopersicum, and the eggplant, S. melongena, with many other members cultivated for medicinal and ornamental uses. While the etymology of the genus’ scientific name is unclear, it may be derived from the Latin word “sol”, meaning "sun," referring to its affinity for sunlight, or from the Latin word “solare”, meaning "to soothe”, the Latin word “solamen”, meaning "a comfort", or the Akkadian word “sululu”, meaning “happy”, in reference to the narcotic effects of some Solanum species after ingestion (Smith, 1971; Wiart, 2006; Quattrocchi, 2012; NZPCN, 2014).

The genus Solanum has been divided into seven subgenera, which are further divided into sections and subsections. The species Solanum rostratum belongs to the prickly Solanum subgenus Leptostemonum and the section Androceras. The Androceras section consists of c. 12 species and is an unusual Solanum section, as it is characterized by mostly north temperate distribution and distinctive zygomorphic, heterantherous, and enantiostylous flowers and prickly calyx tubes that tightly and completely encase the berries (Whalen, 1979; Stern et al., 2010).

In the literature this species has often and incorrectly been called Solanum cornutum, which is distinct from Solanum cornutum Lamarck. The species name rostratum is derived from the Latin word for “beaked”, in reference to the shape of its flowers (Smith, 1971).

Individual plants reach 1-1.5 m tall, with once- or twice-pinnatifid leaves, and abundant prickles on the stems and leaves. It produces yellow flowers with pentagonal corollas 2-3.5 cm in diameter and weakly bilaterally symmetric (Whalen, 1979). In its native range S. rostratum is pollinated by medium- to large-sized bees including bumblebees (Bowers 1975). Flowers bear two sets of anthers that are unequal in size and may be distinctly coloured (Vallejo-Marín et al.. 2009). The fruit, a berry, is enclosed by a prickly calyx and the seeds are released when the berries dry and split while still attached to the plant. [Taken from Vallejo-Marin, 2014].

S. rostratum is an annual weed originating from the Americas (USDA-ARS, 2014). The species may have migrated north across the USA via cattle or horses from northern Mexico and Texas (hence the common name ‘Texas nettle’) (Todd, 1882; DuBois et al., 1896; Tower, 1906), although it may also be native (USDA-ARS, 2014). S. rostratum was reportedly in Colorado by 1877 and Illinois and Tennessee by 1888 (DuBois et al., 1896). It may have then spread by trade routes connecting the Americas to Asia and elsewhere, as suggested by recent research indicating a shared origin of populations in China with U.S. populations (Zhao et al., 2013). The species was introduced to the British Isles sometime in the 1800’s (Vallejo-Marin, 2014).

Although it is native to North-Central America, S. rostratum does not appear to be widespread or weedy in South America; it is not included, for example, in Forzza et al.’s (2010) flora of Brazil or Funk et al.’s (2007) work on the Guianea Shield. The species was also a ‘recent’ introduction to Africa as of 1986 and is lower priority for invasive concern on this continent (Jaeger and Hepper, 1986).

S. rostratum is a recent introduction to Asia. Som Deva (1976) reported it as a new record to India in 1976. In China, it was first recorded in Liaoning province in 1981, but has since spread across a large area in northern China, where there is ongoing dispersal (Zhao et al., 2013). 

Soil drainage

• free
• seasonally waterlogged

Soil texture

• heavy
• light
• medium

S. rostratum reproduces by seeds, which are numerous and dispersed by both biotic and abiotic vectors. The species has the ability to self-propel its seeds by its dehiscent berries (Whalen, 1979; CSU, 2014). Seeds are also dispersed by water, as the fruit can float (DEPI-AU, 2014), and by the wind, as this species is a common tumbleweed (Whalen, 1979; CSU, 2014). Its prickly fruit easily attach to wool, clothes, and manmade items by which humans may aid in its dispersal. It is also likely that dispersal is facilitated by accidental transport in contaminated grain or forage as it often grows on the margins of crop fields (Zhao et al., 2013). The species is also known to have escaped cultivation (Randall, 2012).

Negative economic impact is likely in areas where tourism is important, as dense, thorny colonies formed by the plant would deter people from passing the area. Similarly, livestock may avoid grazing areas in pastures where this species occurs. Regarding human and animal health, if ingested the plant is poisonous.

As S. rostratum is a weed of agriculture, the species negatively impacts crop production, not only by competing for resources and space, but also by contaminating seeds and products such as wool (DEPI-AU, 2014). 

S. rostratum poses a negative impact to the environment, as it forms dense colonies and, once established, is difficult to eradicate. 

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Fast growing
• Has high reproductive potential

• Damaged ecosystem services
• Negatively impacts agriculture
• Negatively impacts human health
• Negatively impacts animal health
• Negatively impacts tourism
• Negatively impacts trade/international relations

• Poisoning
• Produces spines, thorns or burrs

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant

S. rostratum is a noxious weed, but has reportedly been used in folkloric medicine to treat coughs (Duke, 2014).