Saintpaulia

Saintpaulia
a Saintpaulia ionantha plant
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Lamiales
Family: Gesneriaceae
Genus: Saintpaulia
H.Wendl.
Species

Saintpaulia goetzeana
Saintpaulia inconspicua
Saintpaulia ionantha
Saintpaulia pusilla
Saintpaulia shumensis

Saintpaulia teitensis
Saintpaulia flowers
Saintpaulia rupicola = S. ionantha ssp. rupicola

Saintpaulias, commonly known as African violets, are a genus of 6–20 species of herbaceous perennial flowering plants in the family Gesneriaceae, native to Tanzania and adjacent southeastern Kenya in eastern tropical Africa. Typically the African violet is a common household indoor plant but can also be an outdoor plant.

Several of the species and subspecies are endangered, and many more are threatened, due to their native cloud forest habitats being cleared for agriculture. The conservation status of Saintpaulia ionantha has been classed as near-threatened.

Description

Saintpaulias, which grow from 6–15 cm tall, can be anywhere from 6–30 cm wide. The leaves are rounded to oval, 2.5–8.5 cm long with a 2–10 cm petiole, finely hairy, and have a fleshy texture. The flowers are 2–3 cm in diameter, with a five-lobed velvety corolla ("petals"), and grow in clusters of 3–10 or more on slender stalks called peduncles. Wild species can have violet, purple, pale blue, or white flowers.

Sizes

Plants can be classified as one of several sizes based on its above-ground diameter. Although the size per category is not set in stone, these are a general guideline.[1][2]

Growth

Temperature

Saintpaulias are highly sensitive to temperature changes, especially rapid leaf cooling. Spilling cold water on African violet leaves causes discoloration. This is thought to be because rapid leaf cooling causes cell vacuole collapse in the palisade mesophyll cells.[3]

Propagation

African violets are commonly propagated asexually. Plants can be divided into smaller daughter plants or even grown from leaf cuttings.[4] Growing African violets from seed is rare and most commercially available plants are produced from cuttings and tissue culture.[5]

Flowering

The African violet is a day-neutral plant regarding flower development.[6][7]

Distribution

Saintpaulias are native to eastern tropical Africa. There is a concentration of species in the Nguru mountains of Tanzania.

Taxonomy

The plants get their common name "African violet" from their superficial resemblance to true violets (Viola, family Violaceae).

The genus is named after Baron Walter von Saint Paul-Illaire (1860–1910), the district commissioner of Tanga province who discovered the plant in Tanganyika (now Tanzania) in Africa in 1892 and sent seeds back to his father, an amateur botanist in Germany. Two British plant enthusiasts, Sir John Kirk and the Reverend W.E. Taylor, had earlier collected and submitted specimens to the Royal Botanic Gardens, Kew, in 1884 and 1887 respectively, but the quality of specimens was insufficient to permit scientific description at that time. The genus Saintpaulia, and original species S. ionantha, were scientifically described by H. Wendland in 1893.[8]

Revisions of the genus by B.L. Burtt expanded the genus to approximately 20 species. Due to recent studies which showed most of the species to be very poorly differentiated, both genetically and morphologically, the number of species has been reduced to six, with the majority of former species reduced to subspecies under S. ionantha, in a recent floristic treatment.[9] As of 2009, 9 species, 8 subspecies, and 2 varieties have been recognized.[10]

Old name vs. current name

The genus is most closely related to Streptocarpus, with recent phylogenetic studies suggesting it has evolved directly from subgenus Streptocarpella.

Cultivation

Saintpaulias are widely cultivated as house plants. Until recently, only a few of these species have been used in breeding programs for the hybrids available in the market; most available as house plants are cultivars derived from Saintpaulia ionantha (syn. S. kewensis). A wider range of species is now being looked at as sources of genes to introduce into modern cultivars.

The African Violet Society of America is the International Cultivar Registration Authority for the genus Saintpaulia and its cultivars.

In culture

African violets have long been associated with mothers and motherhood. For this reason they have been a traditional gift to mothers in many cultures around the world. African violets are also associated with Easter and Valentine's Day.[5]

References

  1. ↑ "Grow-African-Violets.com". Retrieved 30 May 2013.
  2. ↑ "The Violet Barn". Retrieved 30 May 2013.
  3. ↑ Kadohama, Noriaki; Tatsuaki Goh; Miwa Ohnishi; Hidehiro Fukaki; Tetsuro Mimura; Yoshihiro Suzuki (February 2013). "Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease". PLOS ONE. 8 (2): e57259. doi:10.1371/journal.pone.0057259.
  4. ↑ Thomas, Paul A. "Growing African Violets". CAES Publications. Retrieved 11 August 2013.
  5. 1 2 Chen, J. "Cultural Guidelines for Commercial Production of African Violets (Saintpaulia ionantha)". University of Florida. Retrieved 13 August 2013.
  6. ↑ Modeling Inflorescence Development of the African Violet (Saintpaulia ionantha Wendl.). James E. Faust and Royal D. Heins, J. AMER. SOC. HORT. SCI. 119(4):727–734. 1994.
  7. ↑ Saintpaulia ionantha, Stromme E, 1985, p. 48–49. In: A. Halevy (ed.). CRC handbook of flowering. vol. 3. CRC Press, Boca Raton, Fla.
  8. ↑ Smithsonian World Checklist of the Gesneriaceae
  9. ↑ Darbyshire (2006) Saintpaulia, pp. 50-72, in Beentjy & Ghazanfar (eds), Fl. Trop. East Africa
  10. ↑ Pilon F (2012) Saintpaulia. The history and origin of the African Violet.
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