Dorstenia

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Dorstenia
Dorstenia hildebrandtii ies.jpg
Pseudanthium of Dorstenia hildebrandtii
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales
Family: Moraceae
Tribe: Dorstenieae
Genus: Dorstenia
L.
Dorstenia contrajerva, the type species, by von Jacquin, 1793.

Dorstenia is a predominately Old and New World plant genus within the mulberry family, Moraceae. Depending on the author, there are said to be 100 to 170 species within this genus, second only in number to the genus Ficus within Moraceae. Dorstenia species are mainly known for their unusual inflorescences and growth habits. Dorstenia is named in honor of the German physician and botanist Theodor Dorsten (1492–1552).[1] The type species is Dorstenia contrajerva.

Growth habit[edit]

Dorstenia is unique in the Moraceae family because of the extremely diverse growth habits and forms of its species. While the majority of Moraceae are woody perennials, Dorstenia species are predominantly herbaceous, succulent, or suffrutescent perennials. Only 10% exhibit the typical woody habit of the Moraceae.[2]

Dorstenia gigas from Socotra.
Dorstenia foetida from East Africa and Arabia.

The spectrum of the genus Dorstenia ranges from small annuals to perennial herbaceous plants with and without rhizomes or tubers, geophytes, lithophytes, epiphytes, woody shrubs and succulents (stem or leaf succulents). Their juice is mostly milky white, rarely yellow or colorless. The hairs that are found on most species are at least partially hook-shaped.

The leaves mostly are arranged in spirals and rosettes, and rarely as two-rowed leaves. The leaf blades may be shield-, hand- or foot-shaped, whole, incised, lobed or feathered. Usually the leaf edges are perforated or notched. The ever-present stipulae are also variable in shape. Usually they are leathery, sometimes large, leaf-like and durable or sometimes small, awl-shaped and quickly falling off.[2]

Reproductive structure and fruits[edit]

The most striking characteristic of Dorstenia is their reproductive structure, called pseudanthium (Greek for "false flower") or in Moraceae hypanthium, which is composed of clusters of tiny unisexual flowers on a disc- or cup-shaped receptacle that are often adorned with bracts of various sizes and shapes. The pseudanthiums can be planar, convex, concave, round, oval, square, lobed, twig, star, boot, or tongue-shaped. Their color varies from green to yellowish and reddish to violet and brown. Beneath the pseudanthium, there are usually bracts, scattered or in rows, sometimes carrying appendages. Sometimes the bracts are absent and only their remaining tooth-shaped, awl-like, spatula-shaped or band-shaped appendages are recognizable.

Dorstenia urceolata from Brazil.

The globular, tapered, or warty flowers are unisexual. The female flowers within the receptacle mature first. The male flowers are either scattered between the female flowers or are concentrated on the outer edge of the receptacle or are separated by a flower-free zone at the outer edge. They are stalked and carry one to four (usually two to three) free or almost free tepals and one to four (usually two to three) stamens. The sunken female flowers carry tubular tepals and a free fruit node with one or two, then mostly unequal scars. The stone fruits are embedded in the broadened inflorescence axis and when mature are scattered by a centrifugal mechanism . Like most members of the Moraceae, Dorstenia species have drupe like fruits that are embedded in the receptable. However, a special feature of Dorstenia drupes is that they explode to release and scatter the seeds by way of a centrifugal mechanism. The stone seeds are usually small with a minuscule endosperm.[2]

Taxonomy[edit]

Dorstenia is part of the Dorstenieae tribe of the family Moraceae, and all three levels of classification are monophyletic from chloroplast and nuclear DNA phylogenies, with morphological characters that also support.[3] The family Moraceae is a part of the monophyletic Rosales order, and within this order the Moraceae is most closely related to the Ulmaceae, Cannabaceae, and Urticaceae families of plants.[4]

Dorstenia indica from South India and Sri Lanka

Evolution[edit]

Fossils of Ficus and Morus fruits have been found on the African continent, and are used to approximate the origin of family Moraceae to a maximum of 135 million years ago. In a recent study using fossil fruits, Bayesian molecular dating, and maximum likelihood, researchers attempted to reconstruct the ancestral history of Dorstenia with ITS (internal transcribed spacer) sequences from ribosomal DNA of 35 Dorstenia species and seven out-group species from the different tribes within the Moraceae. The goal was to resolve a long-standing issue within Dorstenia of if this genus diverged and radiated prior to the split of Africa and South American about 105 mya, and members of this genus are on separate continents by vicariance, or if this genus diverged post split and Dorstenia became established in the Neotropics by seed dispersal.[5]

This study produced an interesting phylogeny that revealed an initial old world divergence around 112.3 mya, divergence and radiance of new world Dorstenia at 67.2 and 30.3 mya respectively, and an old world group nested within the new world that radiated around 13.6 mya. The results of this phylogeny do not determine if vicariance or seed dispersal is the cause behind the old and new world populations of Dorstenia; however, it does pose several hypotheses regarding how the new world population came about as well as how three old world Dorstenia species are nested in the new world clade of the phylogeny. Due to the small endosperm that is typical of Dorstenia seeds, it is unlikely that seed dispersal by animals is the reason for the new world and reemerged old world species. However, it is possible that the new world population emerged by transport over the Beringia, established populations all throughout the North and South Americas, and when climate conditions changed and North America was no longer tropical or subtropical that the North American population died out, leaving only the New World population seen today in South America. This idea also allows for the Old World species nested within the new world by Dorstenia populations established in America returning to Africa by Beringia. For this hypothesis to receive more credence, fossil Dorstenia plants in North America would be needed.[5]

Distribution and habitat[edit]

The species are fairly equally distributed between the Afrotropics and Neotropics. Only one species grows east of Arabia, in the tropical forests of Southern India and Sri Lanka.

Uses[edit]

South American species such as Dorstenia contrajerva and Dorstenia brasiliensis[6] are a source of the herbal preparation contrayerva that has been used as a tonic and febrifuge, and as an antidote in South American folk medicine.[6][7] In North America powder made from the rootstocks and leaves of Dorstenia contrajerva is mixed with tobacco for improving the taste of cigarettes.[8] In Oman the tubers of Dorstenia foetida are cooked and eaten.[9] Dorstenia barteri is used in West African folk medicine. Scientific research has shown that it contains numerous flavonoid compounds that have anti-microbial, anti-reverse transcriptase, and anti-inflammatory effects.[10][11]

Species[edit]

In the past many species were described that are now considered synonyms. This is due to the great variability of many Dorstenia species. New species are still discovered, such as Dorstenia luamensis a hanging litophyte from Congo, first described in 2014.[12] The following list only contains the accepted species (without varieties) as listed in The Plant List.[13]

  1. Dorstenia africana
  2. Dorstenia afromontana
  3. Dorstenia albertii
  4. Dorstenia alta
  5. Dorstenia angusticornis
  6. Dorstenia annua
  7. Dorstenia appendiculata
  8. Dorstenia arifolia
  9. Dorstenia aristeguietae
  10. Dorstenia africana
  11. Dorstenia astyanactis
  12. Dorstenia bahiensis
  13. Dorstenia barnimiana
  14. Dorstenia barteri
  15. Dorstenia belizensis
  16. Dorstenia benguellensis
  17. Dorstenia bergiana
  18. Dorstenia bicaudata
  19. Dorstenia bonijesu
  20. Dorstenia bowmaniana
  21. Dorstenia brasiliensis
  22. Dorstenia brevipetiolata
  23. Dorstenia brownii
  24. Dorstenia buchananii
  25. Dorstenia caatingae
  26. Dorstenia caimitensis
  27. Dorstenia carautae
  28. Dorstenia cayapia
  29. Dorstenia ciliata
  30. Dorstenia choconiana
  31. Dorstenia colombiana
  32. Dorstenia conceptionis
  33. Dorstenia contensis
  34. Dorstenia contrajerva
  35. Dorstenia convexa
  36. Dorstenia crenulata
  37. Dorstenia cuspidata
  38. Dorstenia dinklagei
  39. Dorstenia dionga
  40. Dorstenia djettii
  41. Dorstenia dorstenioides
  42. Dorstenia drakena
  43. Dorstenia elata
  44. Dorstenia ellenbeckiana
  45. Dorstenia elliptica
  46. Dorstenia embergeri
  47. Dorstenia erythranda
  48. Dorstenia excentrica
  49. Dorstenia fawcettii
  50. Dorstenia flagellifera
  51. Dorstenia foetida
  52. Dorstenia gigas
  53. Dorstenia goetzei
  54. Dorstenia grazielae
  55. Dorstenia gypsophila
  56. Dorstenia hildebrandtii
  57. Dorstenia hildegardis
  58. Dorstenia hirta
  59. Dorstenia holstii
  60. Dorstenia indica
  61. Dorstenia involuta
  62. Dorstenia jamaicenis
  63. Dorstenia kameruniana
  64. Dorstenia lanei
  65. Dorstenia lavrani
  66. Dorstenia le-testui
  67. Dorstenia lindeniana
  68. Dorstenia lujae
  69. Dorstenia mannii
  70. Dorstenia mariae
  71. Dorstenia milaneziana
  72. Dorstenia nummularia
  73. Dorstenia nyungwensis
  74. Dorstenia oligogyna
  75. Dorstenia panamensis
  76. Dorstenia paucibracteata
  77. Dorstenia peltata
  78. Dorstenia peruviana
  79. Dorstenia petraea
  80. Dorstenia picta
  81. Dorstenia poinsettiifolia
  82. Dorstenia prorepens
  83. Dorstenia psilurus
  84. Dorstenia ramosa
  85. Dorstenia renulata
  86. Dorstenia richardii
  87. Dorstenia rocana
  88. Dorstenia roigii
  89. Dorstenia scaphigera
  90. Dorstenia schliebenii
  91. Dorstenia setosa
  92. Dorstenia socotrana
  93. Dorstenia soerensenii
  94. Dorstenia solheidii
  95. Dorstenia subdentata
  96. Dorstenia subrhombiformis
  97. Dorstenia tayloriana
  98. Dorstenia tenera
  99. Dorstenia tentaculata
  100. Dorstenia tenuiradiata
  101. Dorstenia tenuis
  102. Dorstenia tessmannii
  103. Dorstenia thikaensis
  104. Dorstenia tuberosa
  105. Dorstenia turbinata
  106. Dorstenia turnerifolia
  107. Dorstenia ulugurensis
  108. Dorstenia umbricola
  109. Dorstenia urceolata
  110. Dorstenia uxpanapana
  111. Dorstenia variifolia
  112. Dorstenia vivipara
  113. Dorstenia warneckei
  114. Dorstenia yambuyaensis
  115. Dorstenia yangambiensis
  116. Dorstenia zambesiaca
  117. Dorstenia zanzibarica
  118. Dorstenia zenkeri

References[edit]

  1. ^ Genaust, Helmut (1976). Etymologisches Wörterbuch der botanischen Pflanzennamen ISBN 3-7643-0755-2
  2. ^ a b c Berg, Cornelis C. (2001). "Moreae, Artocarpeae, and Dorstenia (Moraceae), with Introductions to the Family and Ficus and with Additions and Corrections to Flora Neotropica Monograph 7". Flora Neotropica. 83: 1–346. 
  3. ^ Clement, Wendy L.; Weiblen, George D. (2009). "Morphological Evolution in the Mulberry Family (Moraceae)". Systematic Botany. 34 (3): 530–552. doi:10.1600/036364409789271155. ISSN 0363-6445. 
  4. ^ Zhang, Shu-dong; Soltis, Douglas E.; Yang, Yang; Li, De-zhu; Yi, Ting-shuang (2011). "Multi-gene analysis provides a well-supported phylogeny of Rosales". Molecular Phylogenetics and Evolution. 60 (1): 21–28. doi:10.1016/j.ympev.2011.04.008. ISSN 1055-7903. PMID 21540119. 
  5. ^ a b Misiewicz, T. M.; Zerega, N. C. (2012). "PHYLOGENY, BIOGEOGRAPHY AND CHARACTER EVOLUTION OF DORSTENIA (MORACEAE)". Edinburgh Journal of Botany. 69 (03): 413–440. doi:10.1017/S096042861200025X. ISSN 0960-4286. 
  6. ^ a b "Contrayerva". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005.  (Subscription or UK public library membership required.)
  7. ^ Grieve, M. “Contrayerva”, A Modern Herbal. Retrieved on 14.10.2017.
  8. ^ Mansfeld's Database of Agricultural and Horticultural Plants. Retrieved 14.10.2017.
  9. ^ Cactus Art Nursery. “Dorstenia sp. ( foetida form)”. Retrieved 14.10.2017.
  10. ^ Kuete, V.; Ngameni, B.; Mbaveng, A.T.; Ngadjui, B.; Meyer, J.J. Marion; Lall, N. (2010). "Evaluation of flavonoids from Dorstenia barteri for their antimycobacterial, antigonorrheal and anti-reverse transcriptase activities". Acta Tropica. 116 (1): 100–104. doi:10.1016/j.actatropica.2010.06.005. ISSN 0001-706X. 
  11. ^ Omisore, N.O.A.; Adewunmi, C.O.; Iwalewa, E.O.; Ngadjui, B.T.; Watchueng, J.; Abegaz, B.M.; Ojewole, J.A.O. (2004). "Antinociceptive and anti-inflammatory effects of Dorstenia barteri (Moraceae) leaf and twig extracts in mice". Journal of Ethnopharmacology. 95 (1): 7–12. doi:10.1016/j.jep.2004.05.022. ISSN 0378-8741. PMID 15374600. 
  12. ^ Leal, M.. “Dorstenia luamensis (Moraceae), a new species from eastern Democratic Republic of Congo,” PhytoKeys 42, 2014: 49-55. https://doi.org/10.3897/phytokeys.42.7604
  13. ^ The Plant List. Retrieved 24.10.2017.

External links[edit]