View source for Streptocarpus sect. Saintpaulia

{{Short description|section of a genus of flowering plants in the family Gesneriaceae}}
{{Use dmy dates|date=March 2018}}
{{Automatic taxobox
|image = Saintpaulia teitensis - Botanical Garden in Kaisaniemi, Helsinki - DSC03656 cropped.jpg
|image_caption = ''[[Streptocarpus teitensis]]'' in cultivation
|taxon = Streptocarpus sect. Saintpaulia
|authority = [[Hermann Wendland|H.Wendl.]]
|subdivision_ranks = Species
|subdivision = [[#Species|See text]].
}}
[[Image:Saintpaulia closeup.jpg|thumb|right|Saintpaulia flowers]]'''''Streptocarpus'' sect. ''Saintpaulia''''' is a section within ''[[Streptocarpus]]'' subgenus ''Streptocarpella''<ref>,{{Cite web|url=https://gesneriads.info/articles/saintpaulia/saintpaulia/taxonomy/greater-merger-current-taxonomic-status/|title=The Great Merger – Current Taxonomic Status {{!}} Gesneriad Reference Web|language=en-US|access-date=2020-03-11}}</ref> consisting of about ten species of [[herbaceous]] [[perennial plant|perennial]] [[flowering plant]]s 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 phylogenetics|molecular phylogenetic]] studies showed that it was nested within the genus ''Streptocarpus''.

Species and [[cultivar]]s are commonly called '''African violets''' (although they are not closely related to true [[Viola (plant)|violets]]) or '''saintpaulias'''. They are commonly used as indoor houseplants, but can also be kept as outdoor plants in certain climates.

Several of the species and subspecies of the section are [[endangered species|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 species|near-threatened]].

== Description ==
{{expand section|plant structure|date=August 2013}}
Saintpaulias, which grow from 6–15&nbsp;cm tall, can be anywhere from 6–30&nbsp;cm wide. The [[leaves]] are rounded to oval, 2.5–8.5&nbsp;cm long with a 2–10&nbsp;cm [[Petiole (botany)|petiole]], finely [[trichome|hairy]], and have a fleshy texture. The [[flower]]s are 2–3&nbsp;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]].<ref>MacDonald, Elvin "The World Book of House Plants" Popular Books</ref>

The plants get their common name "African violet" from their superficial resemblance to true [[Violet (plant)|violet]]s (''Viola'', family [[Violaceae]]).

==Taxonomy==
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|Tanga province]], [[German East Africa|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  named the genus for Saint Paul-Illaire and his father.<ref>Burkhardt, Lotte. Verzeichnis eponymischer Pflanzennamen. Erweiterte Edition. 2018.</ref> 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 [[Hermann Wendland|H. Wendland]] in 1893.<ref>Smithsonian World Checklist of the Gesneriaceae</ref>

Revisions of the genus by [[Brian Laurence Burtt|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 [[morphology (biology)|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''.<ref>Darbyshire (2006) ''Saintpaulia'', pp. 50-72, in Beentjy & Ghazanfar (eds), Fl. Trop. East Africa</ref> In 2009, 9 [[species]], 8 [[subspecies]], and 2 varieties were recognized.<ref>Pilon F (2012) ''Saintpaulia''. The history and origin of the African Violet.</ref>

A [[Molecular phylogenetics|molecular phylogenetic]] study in 2015 confirmed previous studies showing that species placed in ''Saintpaulia'' were deeply embedded within the genus ''Streptocarpus'',<ref name=NishHughBrigHast15/> supporting the transfer of all ''Saintpaulia'' species to ''Streptocarpus'' in 2012.<ref name=Chri12/> Former ''Saintpaulia'' species did form a [[Monophyly|monophyletic group]], and were placed in section ''Saintpaulia'' of ''Streptocarpus'' subgenus ''Streptocarpella''.<ref name=NishHughBrigHast15/>

===Species===
All the species previously placed in the genus ''Saintpaulia'' are now placed in ''Streptocarpus'' section ''Saintpaulia''. Ten species were recognized, {{As of|2020|March|lc=yes}}.<ref name=NishHughBrigHast15/><ref name=POWO_Saintpaulia/>
{{Div col|colwidth=24em}}
* ''[[Streptocarpus afroviola]]'' <small>Christenh.</small>
* ''[[Streptocarpus albus]]'' <small>(E.A.Bruce) I.Darbysh.</small>
* ''[[Streptocarpus brevipilosus]]'' <small>(B.L.Burtt) Mich.Möller & Haston</small>
* ''[[Streptocarpus goetzeanus]]'' <small>(Engl.) Christenh.</small>
* ''[[Streptocarpus inconspicuus]]'' <small>(B.L.Burtt) Christenh.</small>
* ''[[Streptocarpus ionanthus]]'' <small>(H.Wendl.) Christenh.</small>
* ''[[Streptocarpus nitidus]]'' <small>(B.L.Burtt) Mich.Möller & Haston</small>
* ''[[Streptocarpus shumensis]]'' <small>(B.L.Burtt) Christenh.</small>
* ''[[Streptocarpus teitensis]]'' <small>(B.L.Burtt) Christenh.</small>
* ''[[Streptocarpus ulugurensis]]'' <small>(Haston) Haston</small>
{{Div col end}}

Formerly recognized ''Saintpaulia'' species and infraspecies are listed below with their accepted name in ''Streptocarpus''.<ref name="POWO_Saintpaulia">{{citation |mode=cs1 |title=Search for ''Saintpaulia'' |work=[[Plants of the World Online]] |publisher=Royal Botanic Gardens, Kew |url=http://www.plantsoftheworldonline.org/?q=Saintpaulia |access-date=2020-03-11 }}</ref>
{{Div col|colwidth=36em}}
*''Saintpaulia alba'' <small>E.A.Bruce</small> = ''[[Streptocarpus albus]]'' <small>(E.A.Bruce) I.Darbysh.</small>
*''Saintpaulia amaniensis'' <small>E.P.Roberts</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
*''Saintpaulia brevipilosa'' <small>B.L.Burtt</small> = ''[[Streptocarpus brevipilosus]]'' <small>(B.L.Burtt) Mich.Möller & Haston</small>
*''Saintpaulia confusa'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
*''Saintpaulia difficilis'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
*''Saintpaulia diplotricha'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' var. ''diplotrichus'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia goetzeana'' <small>Engl.</small> = ''[[Streptocarpus goetzeanus]]'' <small>(Engl.) Christenh.</small>
*''Saintpaulia grandifolia'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''grandifolius'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia grotei'' <small>Engl.</small> = ''[[Streptocarpus]] ionanthus'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
*''Saintpaulia inconspicua'' <small>B.L.Burtt</small> = ''[[Streptocarpus inconspicuus]]'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia intermedia'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''pendulus'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia ionantha'' <small>H.Wendl.</small> = ''[[Streptocarpus ionanthus]]'' <small>(H.Wendl.) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''grandifolia'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''grandifolius'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''grotei'' <small>(Engl.) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''mafiensis'' <small>I.Darbysh. & Pócs</small> = ''Streptocarpus ionanthus'' subsp. ''mafiensis'' <small>(I.Darbysh. & Pócs) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''nitida'' <small>(B.L.Burtt) I.Darbysh.</small> = ''[[Streptocarpus nitidus]]'' <small>(B.L.Burtt) Mich.Möller & Haston</small>
**''Saintpaulia ionantha'' subsp. ''occidentalis'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''occidentalis'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''orbicularis'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''orbicularis'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''pendula'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''pendulus'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''rupicola'' <small>(B.L.Burtt) I.Darbysh..</small> = ''Streptocarpus ionanthus'' subsp. ''rupicola'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' subsp. ''velutina'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' subsp. ''velutinus'' <small>(B.L.Burtt) Christenh.</small>
**''Saintpaulia ionantha'' var. ''diplotricha'' <small>(B.L.Burtt) I.Darbysh.</small> = ''Streptocarpus ionanthus'' var. ''diplotrichus'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia kewensis'' <small>C.B.Clarke</small> = ''[[Streptocarpus ionanthus]]'' <small>(H.Wendl.) Christenh.</small>
*''Saintpaulia magungensis'' <small>E.P.Roberts</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''grotei'' <small>(Engl.) Christenh.</small>
**''Saintpaulia magungensis'' var. ''occidentalis'' <small>B.L.Burtt</small> = ''Streptocarpus ionanthus'' subsp. ''occidentalis'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia nitida'' <small>B.L.Burtt</small> = ''[[Streptocarpus nitidus]]'' <small>(B.L.Burtt) Mich.Möller & Haston</small>
*''Saintpaulia orbicularis'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''orbicularis'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia pendula'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''pendulus'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia pusilla'' <small>Engl.</small> = ''[[Streptocarpus afroviola]]'' <small>Christenh.</small>
*''Saintpaulia rupicola'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''rupicola'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia shumensis'' <small>B.L.Burtt</small> = ''[[Streptocarpus shumensis]]'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia teitensis'' <small>B.L.Burtt</small> = ''[[Streptocarpus teitensis]]'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia tongwensis'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' <small>(H.Wendl.) Christenh.</small>
*''Saintpaulia ulugurensis'' <small>Haston</small> = ''[[Streptocarpus ulugurensis]]'' <small>(Haston) Haston</small>
*''Saintpaulia velutina'' <small>B.L.Burtt</small> = ''[[Streptocarpus ionanthus]]'' subsp. ''velutinus'' <small>(B.L.Burtt) Christenh.</small>
*''Saintpaulia watkinsii'' <small>Haston</small> = ''[[Streptocarpus afroviola]]'' var. ''watkinsii'' <small>(Haston) Christenh.</small>
{{Div col end}}

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

==Cultivation==
[[File:Saintpaulia 'Pink Amiss' 02.jpg|thumb|Cultivar 'Pink Amiss']]
Saintpaulias are widely cultivated as [[house plant]]s. 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 [[cultivar]]s 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.

===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.<ref>{{cite web|title=Grow-African-Violets.com|url=http://www.grow-african-violets.com/african-violet-plant-size.html|access-date=30 May 2013}}</ref><ref>{{cite web|title=The Violet Barn|url=http://www.robsviolet.com/african_violets.htm|access-date=30 May 2013}}</ref>
* Micro: less than 3 inches
* Super-mini: 3 to 4 inches
* Mini: between 4 and 6 inches
* Semi-mini: between 6 and 8–10 inches
* Standard: between 8–10 and 12–16 inches
* Large/Giant: over 12–16 inches

=== 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.<ref name="Plos—Vacuole collapse">{{cite journal|last=Kadohama|first=Noriaki|author2=Tatsuaki Goh |author3=Miwa Ohnishi |author4=Hidehiro Fukaki |author5=Tetsuro Mimura |author6=Yoshihiro Suzuki |title=Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease|journal=PLOS ONE|date=February 2013|volume=8|issue=2|doi=10.1371/journal.pone.0057259|pages=e57259 |pmid=23451194 |pmc=3581458|doi-access=free}}</ref>

=== Propagation ===
African violets are commonly [[Plant propagation|propagated]] [[asexual reproduction|asexually]]. Plants can be divided into smaller daughter plants or even grown from leaf cuttings.<ref name="Growing African violets">{{cite web|last=Thomas|first=Paul A|title=Growing African Violets|url=http://www.caes.uga.edu/publications/pubDetail.cfm?pk_ID=6342|publisher=CAES Publications|access-date=11 August 2013}}</ref>
Growing African violets from [[seed]] is rare and most commercially available plants are produced from cuttings and [[tissue culture]].<ref name="Commercial culture of Saintpaulia" />

=== Flowering ===
The African violet is a [[Photoperiodism|day-neutral plant]] regarding flower development.<ref>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.</ref><ref>Saintpaulia ionantha, Stromme E, 1985, p. 48–49. In: A. Halevy (ed.). CRC handbook of flowering. vol. 3. CRC Press, Boca Raton, Fla.</ref>

==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]].<ref name="Commercial culture of Saintpaulia">{{cite web|last=Chen|first=J|title=Cultural Guidelines for Commercial Production of African Violets (Saintpaulia ionantha)|url=http://edis.ifas.ufl.edu/ep360|publisher=University of Florida|access-date=13 August 2013}}</ref>

==References==
{{Reflist|refs=
<ref name=Chri12>{{Citation |mode=cs1 |last1=Christenhusz |first1=Maarten J.M. |date=2012 |title=On African violets and Cape primroses—towards a monophyletic ''Streptocarpus'' (Gesneriaceae) |journal=Phytotaxa |volume=46 |pages=3–9 |url=https://www.researchgate.net/publication/285527411 |access-date=2020-03-12 |doi=10.11646/phytotaxa.46.1.2 }}</ref>

<ref name=NishHughBrigHast15>{{Citation |mode=cs1 |last1=Nishii |first1=Kanae |last2=Hughes |first2=Mark |last3=Briggs |first3=Marie |last4=Haston |first4=Elspeth |last5=Christie |first5=Frieda |last6=DeVilliers |first6=Margaret J. |last7=Hanekom |first7=Thea |last8=Roos |first8=Wiets G. |last9=Bellstedt |first9=Dirk U. |last10=Möller |first10=Michael |date=2015 |title=''Streptocarpus'' redefined to include all Afro-Malagasy Gesneriaceae: Molecular phylogenies prove congruent with geographical distribution and basic chromosome numbers and uncover remarkable morphological homoplasies |journal=Taxon |volume=64 |issue=6 |pages=1243–1274 |url=https://gesneriads.info/wp-content/uploads/2019/02/1243_1274_Nishii-downsized.pdf |access-date=2020-03-12 |doi=10.12705/646.8 |name-list-style=amp }}</ref>
}}

==External links==
{{Commons category|position=left}}
{{Wikispecies}}
*[http://www.avsa.org African Violet Society of America website]
*[http://avsc.ca African Violet Society of Canada website]
*[https://web.archive.org/web/20061002074753/http://www.gesneriads.ca/saintart.htm Gesneriad Reference Web Saintpaulia article]
*[http://www.babyviolets.com Baby Violets - African Violet Houseplants]

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[[Category:Afromontane flora]]
[[Category:Endemic flora of Tanzania]]
[[Category:Flora of East Tropical Africa]]
[[Category:Garden plants of Africa]]
[[Category:House plants]]
[[Category:Streptocarpus| ]]
[[Category:Plant sections]]