Dodonaea

Dodonaea
Dodonaea viscosa foliage and flowers
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Sapindales
Family: Sapindaceae
Subfamily: Dodonaeoideae
Genus: Dodonaea
Mill.[1]
Species

See text

Dodonaea is a genus of about 70 species of flowering plants, often known as hop-bushes, in the soapberry family, Sapindaceae. It has a cosmopolitan distribution in tropical, subtropical and warm temperate regions of Africa, the Americas, southern Asia and Australasia. By far the highest species diversity is in Australia. The genus is named after Rembert Dodoens, also known as Rembertus Dodonaeus.

They are shrubs and small trees growing to 1–5 metres (3.3–16.4 ft) tall. The leaves are alternate, simple or pinnate. The flowers are produced in short racemes. The fruit is a capsule, often with two or three wings. Dodonaea species are used as food plants by the larvae of some Lepidoptera species including Aenetus eximia and Aenetus ligniveren.

Systematics

Dodonaea is recognized as the largest genus of Sapindaceae. This taxa includes 70 species widely distributed in continental Australia.[2] The only other species of the Dodonaea widely spread beyond mainland Australia, Dodonaea viscosa, is believed to be one of the world’s greatly disseminated transoceanic plants.[2]

The first attempts to distinguish infrageneric categories within Dodonaea genus were based on leaf morphology, specifically, two sections - Eu-Dodonaea (simple leaves) and Remberta (pinnate leaves) were differentiated.[2] Later this sectional classification was expanded by Bentham, who included 39 species in five series - four simple-leaved series further divided on capsule-appendage morphology (series Cyclopterae, Platypterae, Cornutae and Apterae) and one pinnate-leaved species (series Pinnatae).

Later the genus have been reviewed extensively two times. Radlkofer identified Dodonaea as a part of the tribe Dodonaeeae, within Dyssapindaceae, together with Loxodiscus, Diplopeltis and Distichostemon. Dodonaea and Distichostemon share similar morphological characteristics which include plants having regular flowers without petals and an intrastaminal disc. Therefore, these two genera are considered to be closely related.[3]

54 Dodonaea species identified by Radlkofer were divided into three series (Cyclopterae, Platypterae and Aphanopterae) and six subseries.[2] As classifiers were taken the presence or absence of an aril and leaves’ glandular structures.

Another revision of the genus was proposed by West, where Dodonaea were divided into six species groups by using a combination of characters.[4] Species with the most primitive characters were classified in Group 1 and Group 6 included plants with the most derived states. For instance, the character of an aril possession was recognized as a derived trait.

The most recent molecular study of phylogenetic relationships within the genus revealed some discrepancy with the previously stated hypotheses of morphological evolution within Dodonaea which classified taxa by the combination of leaf, capsule and seed characters. As in preceding morphological research,[4] species with compound leaves were identified in several clades, interspersed among species with simple leaves (e.g. D. humilis is the only species in Clade I with imparipinnate leaves). The breeding system has great variation across the phylogeny, and although most species are dioecious, sometimes some species may differ from this state being monoecious. Most genera in Sapindaceae are dioecious, however, most closely related to Dodonaea in the phylogeny (Diplopeltis, Diplopeltis stuartii and Cossinia) are monoecious. It has also been reported that whereas normally breeding system in Harpullia is dioecism, a few species have also been recognized as monoecious.[5] It was stated that during evolution a general breeding-system across the phylogeny was dioecism, however, the polygamous state was intermediate or, might be partially reversible.

Molecular data supports an evidence that monophyly of Dodonaea includes all species of Distichostemon.[2] It is also supported by the morphological characters as synapomorphies of flowers with reduced petal number and with a highly reduced intrastaminal disk, the trait which is absent in staminate flowers. Both West and Radlkofer used an aril presence or absence as a character to define species groups. All the main clades of Dodonaea and also two species of Diplopeltis have small funicular arils.[2] Seeds of D. viscosa have very small funicular aril, and are harvested by Pheidole sp. of ants and deposited in middens outside the nest after the elaiosome has been consumed.[6]

Bayesian MCMC estimation of Dodonaea phylogeny supported the hypothesis that two species of Cossinia are sisters to Diplopeltis and Dodonaea.[2] Nevertheless, Diplopeltis is identified as a paraphyletic group. The monophyly of Dodonaea is well supported by Bayesian MCMC estimation (1.00 posterior probability, PP).[2] Within the Clade I (1.00 PP) eight species are recognized as sister to the remaining Dodonaea. Distichostemon is placed in the Clade II (1.00 PP). The phylogeny of remaining 53 species of Dodonaea (1.00 PP) is poorly supported (<0.95 PP).

Dodonaea viscosa is placed within the Clade IV being closely related to D.biloba, D.procumbens and D.camfieldii. It is known that D. viscosa and D. camfieldii evolved in Australia from their most recent common ancestor.[2] D.viscosa is widely distributed in Australia today while D. camfieldii is restricted to New South Wales. The divergence of these taxa occurred approximately in the Late Pliocene to Early Pleistocene (2.7–1.4 Ma, 95% Highest Posterior Density, HPD). The molecular data shows evidence that a monophyletic D. viscosa includes two species, D. procumbens and D. biloba.

Clade I: D. triquetra SE, D. triangularis MT, D. lanceolata MTEr, D. serratifolia SE, D. trifida SW, D. bursariifolia SWSE, D. amblyophylla SW.

Clade II: Distichostemon arnhemicus MT, Distichostemon malvaceus MT, Distichostemon hispidulus var aridus MT, Distichostemon hispidulus var hspidulus MT, Distichostemon dodocandrus MT, Distichostemon barklyanus MT, Distichostemon filamentosus MT.

Clade III a: D. humifusa SW, D. ceratocarpa SW, D. pinifolia SW, D. ericoides SWEr, D. D.ivaricata SW, D. caespitosa SW, D. tepperi SE, D. hexandra SE, D. stenophylla MT,D. pachyneura Er, D. rigidia Er, D. baueri SEEr.

Clade III b: D. platyptera MT, D. adenophora ErSW, D. microzyga Er, D. polyzyga MT, D. physocarpa MT, D. madagascariensis Os, D. stenozyga ErSWSE, D. polyandra MTOs, D. concinna SW, D. larreoides E.

Clade IV: D. vestita MT, D. procumbens SE, D. biloba SE, D. viscosa ErSWSEMTOs, D. camfieldii SE.

Clade V: D. rupicola SE, D. boroniifolia SEMT, D. pinnata SE, D. multijuga SE, D. filiformis SE, D. macrossanii SE, D. oxyptera M.

Clade VI: D. falcata SE, D. peduncularis SEMT, D. filifolia MT, D. uncinata MT, D. hackettiana SW, D. coriacea Er, D. hirsuta SE.

Clade VII: D. truncatiales SE, D. rhombifolia SE, D. megazyga SE, D. tenuifolia SEMT, D. heteromorpha SE, D. inaequifolia SWEr, D. ptarmicaefolia SW, D. lobulata ErSWSE, D. aptera SW, D. intricata SE, D. sinuolata ssp sinuolata SE.

Species

Formerly placed here:

References

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  1. ↑ "Genus: Dodonaea Mill.". Germplasm Resources Information Network. United States Department of Agriculture. 2006-03-26. Retrieved 2009-03-06.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Harrington M., Gadek P. A species well travelled – the Dodonaea viscosa (Sapindaceae) complex based on phylogenetic analyses of nuclear ribosomal ITS and ETSf sequences. Journal of Biogeography. Volume 36, Issue 12, pages 2313–2323, December 2009
  3. ↑ Müller J, Leenhouts P.W. A general survey of pollen types in Sapindaceae in relation to taxonomy. In ‘The evolutionary significance of the exine’. Pages. 407–445. 1976
  4. ↑ 4.0 4.1 West J.G. A revision of Dodonaea Miller (Sapindaceae) in Australia. Brunonia 7, 1–194. 1984
  5. ↑ Leenhouts P.W., Vente M. A. Taxonomic revision of Harpullia (Sapindaceae). Blumea 28, 1–51. 1982
  6. ↑ Harrington G.N., Driver M.A. The effect of fire and ants on the seed-bank of a shrub in a semi-arid grassland. Australian Journal of Ecology 20, 538–547.1995
  7. ↑ 7.0 7.1 "GRIN Species Records of Dodonaea". Germplasm Resources Information Network. United States Department of Agriculture. Retrieved 2011-03-01.