Streptocarpus sect. Saintpaulia | |
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Streptocarpus ionanthus in cultivation | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Lamiales |
Family: | Gesneriaceae |
Genus: | Streptocarpus |
Subgenus: | S. subg. Streptocarpella |
Section: | S. sect. Saintpaulia H.Wendl. |
Species | |
Streptocarpus sect. Saintpaulia is a section within Streptocarpus subgenus Streptocarpella [1] consisting of about ten species of herbaceous perennial flowering plants in the family Gesneriaceae, native to Tanzania and adjacent southeastern Kenya in eastern tropical Africa. The section was previously treated as a separate genus, Saintpaulia, but molecular phylogenetic studies showed that it was nested within the genus Streptocarpus.
Species and cultivars are commonly called African violets (although they are not closely related to true violets) or saintpaulias. They are commonly sold as house plants.
Several of the species and subspecies of the section are endangered, and many more are threatened, as their native cloud forest habitats are cleared for agriculture. The conservation status of Streptocarpus ionanthus has been classed as near-threatened.
This section needs expansionwith: plant structure. You can help by adding to it. (August 2013) |
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. [2]
The plants get their common name "African violet" from their superficial resemblance to true violets (Viola, family Violaceae).
This group of plants has lived in the biodiverse Eastern Arc Usambara Mountains in Tanga Province for millions of years. The name in the local Kisambaa language is Dughulushi. The Germans officially colonialized this area from about 1885, and shortly before this, Baron Walter von Saint Paul-Illaire (1860–1940) was made district commissioner of Tanga province, Tanganyika (now Tanzania) in Africa. He used to enjoy walking in the rainforest and they reminded him of the violets back home. He called them Usambaraveilchen (Usambara violets). In 1892 he sent seeds back to his father, who gave them to an amateur botanist, Hermann Wendland, in Germany. Wendland scientifically described the genus Saintpaulia, and original species S. ionantha in 1893, [3] naming the genus for Saint Paul-Illaire and his father. [4] 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.
Revisions of the genus by B.L. Burtt expanded the genus to approximately 20 species. Following studies which showed most of the species to be very poorly differentiated, both genetically and morphologically, the number of species was reduced to six in a 2006 treatment, with the majority of former species reduced to subspecies under S. ionantha. [5] In 2009, 9 species, 8 subspecies, and 2 varieties were recognized. [6]
A molecular phylogenetic study in 2015 confirmed previous studies showing that species placed in Saintpaulia were deeply embedded within the genus Streptocarpus, [7] supporting the transfer of all Saintpaulia species to Streptocarpus in 2012. [8] Former Saintpaulia species did form a monophyletic group, and were placed in section Saintpaulia of Streptocarpus subgenus Streptocarpella. [7]
All the species previously placed in the genus Saintpaulia are now placed in Streptocarpus section Saintpaulia. Ten species were recognized, as of March 2020 [update] . [7] [9]
Formerly recognized Saintpaulia species and infraspecies are listed below with their accepted name in Streptocarpus. [9]
Saintpaulias are native to eastern tropical Africa. There is a concentration of species in the Nguru mountains of Tanzania.
Saintpaulias are widely cultivated as house plants. Until recently, only a few of the ten or so species that exist have been used in breeding programs for the hybrids available in the market; most of the cultivars available as house plants are derived from Streptocarpus ionanthus (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 section and its cultivars.
Plants can be classified as one of several sizes based on their above-ground diameter. The size per category is not rigid, but a general guideline. [10] [11]
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. [12]
African violets are commonly propagated asexually. Plants can be divided into smaller daughter plants or even grown from leaf cuttings. [13] Growing African violets from seed is rare, and most commercially available plants are produced from cuttings and tissue culture. [14]
The African violet is a day-neutral plant regarding flower development. [15] [16]
African violets have become a traditional gift in the developed world. They are often offered for sale at holidays. [14]
They are a popular house plant in many countries, as they can flower during most of the year and are fairly durable to neglect. [17] [18]
In the 1997 film Amistad , ex-president John Quincy Adams shows the lead slave Joseph Cinqué his flower collection which contains an African violet which Cinque then recognises from his home land.[ citation needed ]
Gesneriaceae, the gesneriad family, is a family of flowering plants consisting of about 152 genera and ca. 3,540 species in the tropics and subtropics of the Old World and the New World, with a very small number extending to temperate areas. Many species have colorful and showy flowers and are cultivated as ornamental plants.
Streptocarpus is an Afrotropical genus of flowering plants in the family Gesneriaceae. The genus is native to Afromontane biotopes from central, eastern and southern Africa, including Madagascar and the Comoro Islands. The flowers are five-petalled, salverform tubes, almost orchid-like in appearance, and hover or arch over the plant, while the pointed, elongate fruit is of a helical form similar to that of the "tusk" of a narwhal. In the wild, species can be found growing on shaded rocky hillsides or cliffs, on the ground, in rock crevices, and almost anywhere the seed can germinate and grow. For the home, there are now many hybrids of various colours and forms available.
Streptocarpus inconspicuus, synonym Saintpaulia inconspicua, is a species of Streptocarpus in the section Saintpaulia. It is a rare African violet, found in the Uluguru Mountains in Tanzania, East Africa. It was first formally described in 1958. It is classed as an endangered species by the IUCN Red List.
Brian Laurence "Bill" Burtt FRSE FLS, was an English botanist and taxonomist who is noted for his contributions to the family Gesneriaceae. In a career that spanned 74 years, he worked first at the Royal Botanic Gardens, Kew, and then at the Royal Botanic Garden Edinburgh (RBGE). He made numerous field trips to South Africa and Sarawak and described a total of 637 new plant species. Burtt is denoted by the author abbreviation B.L.Burtt when citing a botanical name.
Streptocarpus rexii is a South African plant in the family Gesneriaceae, occurring widely from the southern Cape along the coastal hills, mountains, wooded ravines and valleys, and moist forests of the east coast, through Natal as far north as the Eastern Transvaal, up to an elevation of about 900 m. This genus of epiphytes and lithophytes, of about 130 species, is mainly African and Mascarene, with four vagrant species in Asia. Streptocarpus, as do other Old World Gesneriaceae, is unusual in that it displays anisocotylous or unequal growth, i.e. one cotyledon continues to grow after germination.
Streptocarpus goetzeanus, synonym Saintpaulia goetzeana, is a species of Streptocarpus in the section Saintpaulia, commonly known as an African violet. It is a small, flowering plant that is used widely in home horticulture. S. goetzeana was first collected in 1898 by W. Goetze, and it was later described as a species by Engler in 1900.
Primulina is a genus of flowering plants in the African violet family Gesneriaceae. In 2011 the genus was expanded with the transfer of many species that had previously been placed in the genus Chirita. In 2016, five species were moved to the genus Deinostigma.
Streptocarpus teitensis, synonym Saintpaulia teitensis, is a species of Streptocarpus in the section Saintpaulia. It is endemic to 1 square kilometer on Mbololo Hill in the Taita Hills of southern Kenya. The total population is estimated at less than 2,500 individual plants in the wild.
Streptocarpus shumensis, synonym Saintpaulia shumensis, is a species of Streptocarpus in the section Saintpaulia. It is endemic to Shume in the west Usambara Mountains and also from the northern Nguru Mountains, both in Tanzania, where it grows at elevations of 1,300 to 2,000 meters above sea level.
Henckelia is a genus of flowering plants in the family Gesneriaceae. Many of its species were formerly placed in Didymocarpus sect. Orthoboea and in the genus Chirita. Many species formerly placed in Henckelia have been moved to Codonoboea and Loxocarpus.
Deinostigma is a genus in the family Gesneriaceae, native to Vietnam and Southern China. In 2016 the genus was expanded with the transfer of several species that had previously been place in the genus Primulina, to include a total of seven species.
The Didymocarpoideae are a subfamily of plants in the family Gesneriaceae. It was formerly the subfamily Cyrtandroideae. This subfamily consists mostly of tropical and subtropical Old World genera, found in Africa, Asia and the Pacific. One species is native to Central and South America.
Streptocarpus ionanthus is a species of Streptocarpus in the section Saintpaulia, commonly known as an African violet. It is native to eastern and southwestern Tanzania.
Streptocarpus afroviola, synonym Saintpaulia pusilla, is a species of flowering plant in the family Gesneriaceae, native to Tanzania. It was first described in 1900 by Adolf Engler as Saintpaulia pusilla. The former genus Saintpaulia was reduced to Streptocarpus sect. Saintpaulia, and the species was moved to Streptocarpus. However, the name Streptocarpus pusillus had been used in 1883 for a different species, so Maarten J. M. Christenhusz put forward the replacement name Streptocarpus afroviola.
Streptocarpus albus is a species of flowering plant in the family Gesneriaceae, native to Tanzania. It was first described in 1933 as Saintpaulia alba. It is found in the Uluguru and Nguru mountains of Tanzania.
Streptocarpus brevipilosus is a species of flowering plant in the family Gesneriaceae, native to Tanzania. It was first described in 1964 as Saintpaulia brevipilosa. The former genus Saintpaulia was reduced to Streptocarpus sect. Saintpaulia in 2015, and the species moved to Streptocarpus. It is found in the Nguru Mountains of Tanzania.
Streptocarpus nitidus is a species of flowering plant in the family Gesneriaceae, native to Tanzania. It was first described in 1958 as Saintpaulia nitida. The former genus Saintpaulia was reduced to Streptocarpus sect. Saintpaulia in 2015, and the species moved to Streptocarpus. Streptocarpus nitidus has also been treated as a subspecies of Streptocarpus ionanthus.
Streptocarpus ulugurensis is a species of flowering plant in the family Gesneriaceae. It is an herbaceous perennial endemic to the Uluguru Mountains of Tanzania.
Loxostigma is a genus of flowering plants belonging to the family Gesneriaceae.