Myosotis exarrhena is a species of flowering plant in the family Boraginaceae, endemic to Australia. Robert Brown described this species as Exarrhena suaveolens in 1810. Plants of this species of forget-me-not are perennial rosettes with ebracteate inflorescences and white corollas with exserted stamens.
| Myosotis exarrhena | |
|---|---|
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| Flowers of Myosotis exarrhena | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Boraginales |
| Family: | Boraginaceae |
| Genus: | Myosotis |
| Species: | M. exarrhena
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| Binomial name | |
| Myosotis exarrhena | |
| Synonyms | |
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Exarrhena suaveolens R.Br. | |
Taxonomy and etymology
editMyosotis exarrhena F.Muell. is in the plant family Boraginaceae. The species was originally described by Robert Brown in his Prodromus in 1810 as Exarrhena suaveolens R.Br.[2] It was transferred to the genus Myosotis as M. suaveolens (R.Br.) Poir. in 1816, but this was an illegitimate name owing to M. suaveolens Waldst. & Kit. ex Willd., which was published in 1809 based on a European type.[3][4] Ferdinand von Mueller finally made the valid combination M. exarrhena in 1889 in the updated Systematic Census of Australian Plants.[1]
The lectotype (K001094009) and the isolectotype (K001094010) of Exarrhena suaveolens are on the same sheet at Kew Herbarium,[5] and were designated by Peter G. Wilson & Jeannie Highet.[4]
Myosotis exarrhena is one of two species native to Australia.[3] Myosotis australis is native to Australia, as well as New Zealand and New Guinea.[3] Myosotis exarrhena is morphologically more similar to other ebracteate-erect species from New Zealand, especially Myosotis concinna,[6] than to M. australis.[3] The Australian M. exarrhena can be distinguished from the New Zealand M. concinna by its white corollas, retrorse hairs on the underside of the rosette leaves and scape, and lack of hooked hairs on the calyx.[6]
The species epithet exarrhena is based on the Greek word arrhen and refers to the exerted anthers.[3]
Phylogeny
editOne individual of Myosotis exarrhena was included in phylogenetic analyses of standard DNA sequencing markers (nuclear ribosomal DNA and chloroplast DNA regions).[7][8]
Within the southern hemisphere lineage, species relationships were not well resolved.[7][8] The individual of M. exarrhena grouped with Australian M. australis and several other mostly ebracteate-erect New Zealand Myosotis species.[7][8]
Description
editMyosotis exarrhena plants are rosettes that are often stoloniferous. The rosette leaves have petioles that are 6–30 mm long. The rosette leaf blades are 7–55 mm long by 2–10 mm wide (length: width ratio 1.0–7.6: 1), lanceolate, oblanceolate or narrowly oblanceolate, widest below, at or above the middle, usually with an obtuse apex. Both surfaces of the leaf are uniformly and densely covered in flexuous to curved, usually appressed, antrorse (forward-facing) hairs that are oriented parallel to the midrib. Each rosette has multiple ascending, branched ebracteate inflorescences that are bifurcating at the top and up to 470 mm long. The cauline leaves are similar to the rosette leaves, but become smaller. The flowers are 36–91 per inflorescence and each is borne on a short pedicel without a bract. The calyx is 2–5 mm long at flowering and 3–6 mm long at fruiting, lobed to half to two-thirds of its length, and densely covered in straight to flexuous, often hooked, patent to erect, mostly antrorse hairs (with some retrorse or backward-facing hairs near the base). The corolla is white and 5–11 mm in diameter, with a cylindrical tube, petals that are usually narrowly ovate or ovate, and small yellow scales alternating with the petals. The anthers are fully exserted. The four smooth, shiny, usually medium to dark brown nutlets are 1.7–2.3 mm long by 1.0–1.5 mm wide and usually ovoid in shape.[3]
The pollen of Myosotis exarrhena is of the exarrhena type.[3]
The chromosome number of M. exarrhena is unknown.[3]
Flowering and fruiting between October–March, with the main flowering period from December–February.[3]
Distribution and habitat
editMyosotis exarrhena is endemic to Australia in the states of New South Wales, Australian Capital Territory, Victoria and Tasmania from 555 to 1000 m ASL, possibly up to 1370 m ASL, in forest, woodland, clearings or stream banks, on slopes, outcrops or banks.[3]
Conservation status
editMyosotis exarrhena is not listed on the Australian Government's EPBC Act list of Threatened Flora.[9] It is likely to be considered to be LC (Least Concern) according to the IUCN.[3]
Hybridisation
editOn the basis of morphological data, Myosotis exarrhena may hybridise with M. australis where the two species are known to co-occur in New South Wales, ACT and Victoria.[3] Several specimens have been identified as interspecific M. exarrhena × M. australis hybrids.[3]
References
edit- ^ a b Ferdinand von Mueller (1889), Second systematic census of Australian plants, with chronologic, literary and geographic annotations;, Melbourne: Printed for the Victorian Government by McCarron. Bird & Co., doi:10.5962/BHL.TITLE.23173, OCLC 5873715, OL 7024831M, Wikidata Q51433898
- ^ Brown, Robert, 1773-1858 (1810), Prodromus florae Novae Hollandiae et Insulae Van-Diemen, exhibens characteres plantarum (in Latin), London: Typis R Taylor, veneunt apud J. Johnson, doi:10.5962/BHL.TITLE.6720, OCLC 9885199, OL 13508332M, Wikidata Q51522645
{{citation}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ a b c d e f g h i j k l m Heidi M. Meudt; Michael J. Thorsen; Jessica Prebble (2020). "Taxonomic revision of the Myosotis australis group (Boraginaceae) native to Australia, New Zealand and New Guinea". Australian Systematic Botany. 33 (6): 477. doi:10.1071/SB20014. ISSN 1030-1887. Wikidata Q107670735.
- ^ a b Peter G. Wilson; Jeannie Highet (1988). "Myosotis exarrhena F.Muell., the correct namefor M. suaveolens (R.Br.) Poir. (Boraginaceae)". Telopea. 3: 283–284. doi:10.7751/TELOPEA19884815. ISSN 0312-9764. Wikidata Q118358923.
- ^ "Lectotype and isolectotype of Myosotis exarrhena on JSTOR". plants.jstor.org. Retrieved 14 May 2023.
- ^ a b Heidi M. Meudt (2021). "Taxonomic revision of five species groups of ebracteate-erect Myosotis (Boraginaceae) endemic to New Zealand, based on morphology, and description of new subspecies". Australian Systematic Botany. 34 (3): 252–304. doi:10.1071/SB20028. ISSN 1030-1887. Wikidata Q107671092.
- ^ a b c Meudt, Heidi M.; Prebble, Jessica M.; Lehnebach, Carlos A. (1 May 2015). "Native New Zealand forget-me-nots (Myosotis, Boraginaceae) comprise a Pleistocene species radiation with very low genetic divergence". Plant Systematics and Evolution. 301 (5): 1455–1471. doi:10.1007/s00606-014-1166-x. ISSN 2199-6881.
- ^ a b c Richard Winkworth; Jürke Grau; Alastair W. Robertson; Peter Lockhart (1 August 2002). "The origins and evolution of the genus Myosotis L. (Boraginaceae)". Molecular Phylogenetics and Evolution. 24 (2): 180–193. doi:10.1016/S1055-7903(02)00210-5. ISSN 1055-7903. PMID 12144755. Wikidata Q30707919.
- ^ "EPBC Act List of Threatened Flora". Species Profile and Threats Database. Retrieved 15 May 2023.
External links
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