{{Short description|Species of flowering plant}} {{Use New Zealand English|date=July 2024}}
{{Use dmy dates|date=April 2022}} {{Speciesbox | image = Myosotis retrorsa 176038783.jpg | status = NU | status_system = NZTCS | status_ref = <ref name="NZTCS"/> | genus = Myosotis | species = retrorsa | authority = Meudt, Prebble and Hindm.-Walls<ref name="csiro">{{Cite journal |last1=Meudt |first1=Heidi M. |last2=Prebble |first2=Jessica M. |date=2018-02-28 |title=Species limits and taxonomic revision of the bracteate-prostrate group of southern hemisphere forget-me-nots (Myosotis, Boraginaceae), including description of three new species endemic to New Zealand |url=https://www.publish.csiro.au/sb/SB17045 |journal=Australian Systematic Botany |language=en |volume=31 |issue=1 |pages=48–105 |doi=10.1071/SB17045 |s2cid=90834744 |issn=1446-5701|url-access=subscription }}</ref> }}
'''''Myosotis retrorsa''''' is a species of [[flowering plant]] in the [[Family (taxonomy)|family]] Boraginaceae, [[Endemic species|endemic]] to the [[South Island]] of [[New Zealand]]. Heidi Meudt, Jessica Prebble and Rowan Hindmarsh-Walls described the species. Plants of this species of [[Forget-me-nots|forget-me-not]] are [[Perennial plant|perennial]] with a prostrate habit, bracteate inflorescences, and white corollas.
== Taxonomy and etymology == ''Myosotis retrorsa'' Meudt et al. is in the plant family [[Boraginaceae]] and was originally described in 2018 by Heid Meudt, Jessica Prebble and Rowan Hindmarsh-Walls.<ref name="csiro">{{Cite journal |last1=Meudt |first1=Heidi M. |last2=Prebble |first2=Jessica M. |date=2018-02-28 |title=Species limits and taxonomic revision of the bracteate-prostrate group of southern hemisphere forget-me-nots (Myosotis, Boraginaceae), including description of three new species endemic to New Zealand |url=https://www.publish.csiro.au/sb/SB17045 |journal=Australian Systematic Botany |language=en |volume=31 |issue=1 |pages=48–105 |doi=10.1071/SB17045 |s2cid=90834744 |issn=1446-5701|url-access=subscription }}</ref><ref name="nzpcn">{{Cite web |title=Myosotis retrorsa |url=https://www.nzpcn.org.nz/flora/species/myosotis-retrorsa/ |access-date=2022-05-10 |website=New Zealand Plant Conservation Network |language=en}}</ref> It is morphologically most similar to ''[[Myosotis pulvinaris|M. pulvinaris]]'' and ''M. lyallii,'' other bracteate-prostrate species of ''Myosotis.<ref name="csiro"/>'' ''Myosotis retrorsa'' can be distinguished from all other bracteate-prostrate species by the retrorse trichomes on the underside of the rosette and cauline leaves, and calyx. Its rosette leaf lamina length : width ratio < 1.3 : 1 can distinguish it from several species including ''M. lyallii'' (but not ''M. pulvinaris''). ''M. retrorsa'' has 1–3 flowers per inflorescence compared to the solitary flowers of ''M. pulvinaris'' and the larger inflorescences of ''M. lyallii'', which have (2–)4–11 flowers.<ref name="csiro" />
The type specimen of ''Myosotis retrorsa'' is lodged at the herbarium (WELT) of the [[Museum of New Zealand Te Papa Tongarewa|Museum of New Zealand, Te Papa Tongarewa]].<ref name="csiro" /><ref>{{Cite web |title=Myosotis retrorsa |url=https://collections.tepapa.govt.nz/object/1534760 |access-date=2022-05-10 |website=collections.tepapa.govt.nz}}</ref>
The specific epithet, ''retrorsa'', is derived from the Latin word ''retrorsus'' (backward-facing) and is a nod to the characteristic retrorse trichomes on the underside of the rosette leaves.<ref name="csiro"/>
== Phylogeny == ''Myosotis retrorsa'' was not included in [[Phylogenetics|phylogenetic]] analyses of standard DNA sequencing markers ([[Ribosomal DNA|nuclear ribosomal DNA]] and [[chloroplast DNA]] regions).<ref name="doi">{{Cite journal |last1=Meudt |first1=Heidi M. |last2=Prebble |first2=Jessica M. |last3=Lehnebach |first3=Carlos A. |date=2015-05-01 |title=Native New Zealand forget-me-nots (Myosotis, Boraginaceae) comprise a Pleistocene species radiation with very low genetic divergence |url=https://doi.org/10.1007/s00606-014-1166-x |journal=Plant Systematics and Evolution |language=en |volume=301 |issue=5 |pages=1455–1471 |doi=10.1007/s00606-014-1166-x |s2cid=14686750 |issn=2199-6881|url-access=subscription }}</ref><ref>{{Cite journal |last1=Winkworth |first1=Richard C |last2=Grau |first2=Jürke |last3=Robertson |first3=Alastair W |last4=Lockhart |first4=Peter J |date=2002-08-01 |title=The origins and evolution of the genus Myosotis L. (Boraginaceae) |url=https://www.sciencedirect.com/science/article/pii/S1055790302002105 |journal=Molecular Phylogenetics and Evolution |language=en |volume=24 |issue=2 |pages=180–193 |doi=10.1016/S1055-7903(02)00210-5 |pmid=12144755 |issn=1055-7903|url-access=subscription }}</ref>
[[File:SP104687 Myosotis retrorsa Meudt et al Te Papa 1534760 564153.jpg|thumb|Holotype specimen of ''Myosotis retrorsa'']]
== Description == ''Myosotis retrorsa'' plants are single rosettes that may cluster together into tufts or loose clumps.. The rosette leaves are 7–30 per plant, and have [[Petiole (botany)|petioles]] 2–9 mm long. The rosette leaf blades are 4–7 mm long by 1–4 mm wide (length: width ratio 0.8–1.7: 1), narrowly obovate to very broadly obovate, or orbicular, widest at or above the middle, with an [[Glossary of leaf morphology#obtuse|obtuse]] apex. The upper surface of the leaf is densely covered in flexuous, appressed to patent, antrorse (forward-facing) hairs that are parallel to the mid vein. The lower surface of the leaf is sparsely to densely covered in flexuous, appressed to patent, retrorse (backward-facing) hairs, sometimes mixed with antrorse hairs, that are parallel or angled relative to the mid vein. Each rosette has 2–15 ascending or prostrate, unbranched or branched, bracteate [[inflorescence]]s that are usually 20–40 cm long. The cauline leaves are similar in size, shape and hairs to the rosette leaves. There can be up to 3 flowers in each inflorescence, each one borne on a short [[Pedicel (botany)|pedicel]] and with a cauline leaf. The calyx is 3–6 mm long at flowering and 5–8 mm long at fruiting, lobed to up to half of its length, and densely covered in short, flexuous, appressed to patent, antrorse hairs and some retrorse hairs near the calyx base. The corolla is white and up to 8 mm in diameter, with a cylindrical tube, petals that are broadly obovate and flat, and small yellow scales alternating with the petals. The anthers are partly exserted, with the tips or the upper third only surpassing the scales. The four smooth, shiny, brown to dark brown nutlets are 1.3–2.2 mm long by 0.8–1.2 mm wide and narrowly ovoid to ovoid in shape.<ref name="csiro"/><ref name="nzpcn"/>
''Myosotis retrorsa'' showed intraspecific variation for pollen type, with either ''M. australis'' or ''M. uniflora'' type pollen.<ref>{{Cite journal |last=Meudt |first=HM |date=2016-10-01 |title=Pollen morphology and its taxonomic utility in the Southern Hemisphere bracteate-prostrate forget-me-nots (Myosotis, Boraginaceae) |url=https://doi.org/10.1080/0028825X.2016.1229343 |journal=New Zealand Journal of Botany |volume=54 |issue=4 |pages=475–497 |doi=10.1080/0028825X.2016.1229343 |s2cid=89118799 |issn=0028-825X|url-access=subscription }}</ref><ref>{{Cite web |title=Myosotis retrorsa |url=https://collections.tepapa.govt.nz/topic/10498 |access-date=2022-05-10 |website=collections.tepapa.govt.nz}}</ref>
The chromosome number of ''M. retrorsa'' is unknown.
It flowers and fruits mainly from December to February.<ref name="csiro"/>
== Gallery == <gallery mode="packed" heights="170"> File:SP002699 Myosotis retrorsa Meudt et al. WELT Te Papa 1468919 389718.jpg|Pollen File:SP108814 Myosotis retrorsa Meudt et al. WELT Te Papa 1863559 592426.jpg|Close up of hairy leaves and calyces File:SP106618 Myosotis retrorsa Meudt et al. WELT Te Papa 1697649 465716.jpg|Plant just past flowering growing on rock File:SP108829 Myosotis retrorsa Meudt et al. WELT Te Papa 1863576 589702.jpg|Close-up of flowers
</gallery>= Distribution and habitat == ''Myosotis retrorsa'' is endemic to the South Island of New Zealand in Otago, Southland and Fiordland from 915 to 1830 m elevation.<ref name="csiro"/> It is found in subalpine outcrops, crevices, and fellfield ridges and cirques on schist, marble.<ref name="csiro"/>
== Cultivation == Although not commonly cultivated, plants of ''Myosotis retrorsa'' have been cultivated at the [[Arctic–Alpine Botanic Garden|Arctic-Alpine Botanic Garden]] in [[Tromsø (city)|Tromsø]], Norway.<ref>{{Cite web |title=Myosotis retrorsa |url=https://www.google.com/search?q=myosotis+retrorsa |access-date=2022-05-10 |website=www.google.com}}</ref>
== Conservation status == The species is listed as At Risk - Naturally Uncommon in the most recent assessment (2017–2018) of the [[New Zealand Threat Classification System|New Zealand Threatened Classification]] for plants. It also has the qualifiers "DP" (Data Poor), and "Sp" (Sparse).<ref name="NZTCS">{{Cite journal |last1=Lange |first1=Peter J. de |last2=Rolfe |first2=Jeremy R. |last3=Barkla |first3=John W. |last4=Courtney |first4=Shannel P. |last5=Champion |first5=Paul D. |last6=Perrie |first6=Leon R. |last7=Beadel |first7=Sarah M. |last8=Ford |first8=Kerry A. |last9=Breitwieser |first9=Ilse |last10=Schönberger |first10=Ines |last11=Hindmarsh-Walls |first11=Rowan |date=May 2018 |title=Conservation status of New Zealand indigenous vascular plants, 2017 |url=https://www.doc.govt.nz/globalassets/documents/science-and-technical/nztcs22entire.pdf |journal=New Zealand Threat Classification Series |volume=22 |pages=1–86 |oclc=1041649797}}</ref>
== References == {{Reflist}}
== External links ==
* [https://avh.ala.org.au/occurrences/search?taxa=myosotis+retrorsa#tab_mapView ''Myosotis retrorsa'' occurrence data from Australasian Virtual Herbarium] {{Taxonbar|from=Q75862685}}
[[Category:Myosotis|retrorsa]] [[Category:Endemic flora of New Zealand]] [[Category:Endangered flora of New Zealand]] [[Category:Plants described in 2018]]