The plants grow from a fleshy tuberous root which is a source of maltodextrins which are used as a sugar substitute. Some species attain a height of 90 cm.
The flowers are solitary or arranged in racemes. The petals and the lip are small. The flowers consist essentially of the sepals. The flowers range in color from very light to dark red.
flowers pollinated by butterflies have evolved twice, for example the pollination of Disa uniflora by the Table mountain Pride Butterfly Aeropetes tulbaghia (Satyrinae)[9]
In a classification of orchids that was published in 2015, Chaseet alii placed Schizodium in synonymy under Disa. They also defined the subtribe Disinae as consisting of Pachites, Disa and Huttonaea. This version of Disinae is probably not monophyletic, but was created as a holding classification, to avoid the unnecessary designation of subtribes before further studies can clarify the relationships of these three genera.[1]
Seeds
The genus can be split into two groups based on the size of the seeds. Those with relatively large balloon-shaped seeds up to 1.5 mm long belong to the Disa uniflora group. The remaining species have seeds that are smaller than 0.7 mm. The Disa uniflora group comprises plants that grow along stream sides: Disa uniflora, Disa tripetaloides, Disa cardinalis, Disa caulescens and Disa aurata. They belong to the few species in Orchidaceae that do not rely on mycorrhizal fungi for germination, and are thought to be an adaptation to hydrochory.[16][17] This pattern was later extended to split the genus into summer rainfall species and non-summer rainfall species. Those in the second group added Disa cornuta to the list of Disa seeds that germinate readily.[18]
Once very rare in cultivation, Disa uniflora is gaining in popularity as a cut flower. However, they are difficult to grow, because of the needed mineral composition of the potting soil. Also, if exposed to excessive moisture, they can be easily killed by rot.
Hybrids
The following species have been used to create more than 400 hybrids : Disa cardinalis, Disa caulescens, Disa racemosa, Disa tripetaloides, Disa uniflora, Disa aurata and Disa venosa.
Disa × brendae (D. caulescens × D. uniflora) (South Africa, SW. Cape Prov.)
Disa × maculomarronina (D. hircicornis × D. versicolor) (S. Africa)..
Disa × nuwebergensis (D. caulescens × D. tripetaloides) (South Africa, Cape Prov.).
Disa × paludicola (D. chrysostachya × D. rhodantha) (South Africa, KwaZulu-Natal).
Species
Species currently (May 2014) recognized:[2]
Disa aconitoides (Ethiopia to S. Africa)
Disa aconitoides subsp. aconitoides (Ethiopia to S. Africa) Tuber geophyte
Disa aconitoides subsp. concinna (Congo to S. Trop. Africa) Tuber geophyte
Disa aconitoides subsp. goetzeana (Ethiopia to Tanzania) Tuber geophyte
Disa aequiloba (SW. Tanzania to Angola)
Disa alinae (Congo)
Disa alticola (Mpumalanga / East-Transvaal)
Disa amoena ( Mpumalanga / East-Transvaal)
Disa andringitrana (SE. & S. Madagascar)
Disa aperta (SW. & S. Tanzania to Zambia)
Disa arida (South Africa, S. Cape Prov.)
Disa aristata (S. Africa, Northern Prov.)
Disa atricapilla (South Africa, SW. Cape Prov.)
Disa atrorubens (South Africa, SW. Cape Prov.)
Disa aurata (South Africa, Cape Prov. (Swellendam)
Disa barbata (South Africa, SW. Cape Prov.)
Disa basutorum (S. Africa (Drakensberg)
Disa baurii (Tanzania to S. Africa)
Disa begleyi (South Africa, SW. Cape Prov.)
Disa bifida (South Africa, SW. & S. Cape Prov.)
Disa biflora (South Africa, SW. & S. Cape Prov.)
Disa bivalvata (South Africa, SW. & S. Cape Prov.)
Disa zuluensis (Mpumalanga / East-Transvaal, KwaZulu-Natal)
References
^ a bMark W. Chase; Kenneth M. Cameron; John V. Freudenstein; Alec M. Pridgeon; Gerardo A. Salazar; Cássio van den Berg; André Schuiteman (2015). "An updated classification of Orchidaceae". Botanical Journal of the Linnean Society. 177 (2): 151–174. doi:10.1111/boj.12234.
^ a bKew World Checklist of Selected Plant Families
^Hans Peter Linder and Hubert Kurzweil. 1999. Orchids of Southern Africa. 504 pages. A. A. Balkema. ISBN 978-90-5410-445-2.
^Weeds Australia, Weed Identification, African weed-orchid, Disa bracteata Archived May 17, 2014, at the Wayback Machine
^Peter Jonas Bergius. 1767. Descriptiones Plantarum ex Capite Bonae Spei: 348. (See External links below).
^Umberto Quattrocchi. 2000. CRC World Dictionary of Plant Names volume II. CRC Press: Boca Raton; New York; Washington,DC;, USA. London, UK. ISBN 978-0-8493-2676-9 (vol. II). (see External links below).
^Waterman, Richard J.; Pauw, Anton; Barraclough, Timothy G.; Savolainen, Vincent (2009). "Pollinators underestimated: A molecular phylogeny reveals widespread floral convergence in oil-secreting orchids (sub-tribe Coryciinae) of the Cape of South Africa". Molecular Phylogenetics and Evolution. 51 (1): 100–110. doi:10.1016/j.ympev.2008.05.020. PMID 18586527.
^Johnson, S.D.; Linder, H.P.; Steiner, K.E. (1998). "Phylogeny and radiation of pollination systems in Disa (Orchidaceae)". American Journal of Botany. 85 (3): 402–411. doi:10.2307/2446333. JSTOR 2446333.
^Johnson, S. D.; Brown, M. (2004). "Transfer of pollinaria on birds' feet: a new pollination system in orchids". Plant Systematics and Evolution. 244 (3): 181–188. doi:10.1007/s00606-003-0106-y. S2CID 23288375.
^Douzery, Emmanuel J. P.; Pridgeon, Alec M.; Kores, Paul; Linder, H. P.; Kurzweil, Hubert; Chase, Mark W. (1999-06-01). "Molecular phylogenetics of Diseae (Orchidaceae): a contribution from nuclear ribosomal ITS sequences". American Journal of Botany. 86 (6): 887–899. doi:10.2307/2656709. ISSN 0002-9122. JSTOR 2656709. PMID 10371730.
^Bytebier, Benny; Bellstedt, Dirk U.; Linder, Hans Peter (2007). "A molecular phylogeny for the large African orchid genus Disa". Molecular Phylogenetics and Evolution. 43 (1): 75–90. doi:10.1016/j.ympev.2006.08.014. PMID 17081772.
^Benny Bytebier; Dirk U. Bellstedt; Hans Peter Linder (2008). "A New Phylogeny-Based Sectional Classification for the Large African Orchid Genus Disa". Taxon. 57 (4): 1233–1251. doi:10.1002/tax.574015. JSTOR 27756776..
^Linder Hans Peter (1981). "Taxonomic studies on the Disinae: 2. A revision of the genus Schizodium Lindl". Journal of South African Botany. 47: 339–371.
^Thompson, David Ian (2003). Conservation of select South African Disa Berg. Species (Orchidaceae) through in vitro seed germination. University of Natal.
^Kurzweil, H. (September 1993). "Seed morphology in Southern African Orchidoideae (Orchidaceae)". Plant Systematics and Evolution. 185 (3–4): 229–247. doi:10.1007/BF00937660. S2CID 41321812.
^Thompson, Dave I.; Edwards, Trevor J.; Staden, Johannes van (2001). "In Vitro Germination of Several South African Summer Rainfall Disa (Orchidaceae) Species: Is Seed Testa Structure a Function of Habitat and a Determinant of Germinability?". Systematics and Geography of Plants. 71 (2): 597–606. doi:10.2307/3668704. JSTOR 3668704.
^PlantZAfrica.com, Disa uniflora Bergius
^Anthony Huxley, Mark Griffiths, and Margot Levy (1992). The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press,Limited: London. The Stockton Press: New York. ISBN 978-0-333-47494-5 (set).
^Eric Harley, Sid Cywes, and H. Peter Linder. 2013. A Disa Companion: The Art and Science of Disa Cultivation. Author House. 123 pages. ISBN 978-1-48179-767-2.
External links
Media related to Disa at Wikimedia Commons
page 348 Archived 2015-12-10 at the Wayback MachineAt: View Book Archived 2016-03-04 at the Wayback MachineAt: Descriptiones plantarum ex Capite Bonae Spei At: Bergius, Peter Jonas At: Biodiversity Heritage Library
CRC World Dictionary of Plant Names: D-L At: Botany & Plant Science At: Life Science At: CRC Press
Dressler, S.; Schmidt, M. & Zizka, G. (2014). "Disa". African plants – a Photo Guide. Frankfurt/Main: Forschungsinstitut Senckenberg.