''Myosotis petiolata'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the order ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the Hawkes Bay region of the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. Joseph Dalton Hooker described the species in 1853. Plants of this species of forget-me-not are

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

rosettes with ebracteate inflorescences and white corollas with exserted stamens.

Taxonomy and etymology

''Myosotis petiolata'' is in the plant family

. The species was described by Joseph Dalton Hooker in 1853 in ''

Flora Novae-Zelandiae The ''Flora Novae-Zelandiae'' is a description of the plants discovered in New Zealand during the Ross expedition written by Joseph Dalton Hooker and published by Reeve Brothers in London between 1853 and 1855. Hooker sailed on HMS ''Erebus'' as ...

''. The lectotype specimen of ''Myosotis petiolata'' was collected by

William Colenso William Colenso (17 November 1811 – 10 February 1899) FRS was a Cornish Christian missionary to New Zealand, and also a printer, botanist, explorer and politician. He attended the signing of the Treaty of Waitangi and later wrote an accou ...

, and the isolectotype is lodged at the herbarium of the Museum of New Zealand, Te Papa Tongarewa (WELT SP023506).'''' The leaves of ''M. petiolata'' are petiolate, i.e. they have a petiole, which may refer to the species epithet, ''petiolata''. ''Myosotis petiolata'' is morphologically and genetically most similar to '' M. pansa'' and '' M. pottsiana.'' These three species are allopatric in their geographic distributions and can be distinguished from one another by a suite of characters that includes corolla diameter (''M. petiolata'': 4.2–10.5 mm; ''M. pansa'': 7.6–14.3 mm; and ''M. pottsiana'': 5.3–9.8 mm).

Phylogeny

To date, no individuals of ''Myosotis petiolata'' have been included in

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses of standard DNA sequencing markers (

nuclear ribosomal DNA Nuclear may refer to: Physics Relating to the Atomic nucleus, nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear ...

and chloroplast DNA regions). However, two to three individuals of ''Myosotis petiolata'' were included in two different studies that phylogenetically analysed amplified fragment length polymorphisms (AFLPs) of the informal ''M. petiolata'' species group. In these analyses, ''Myosotis petiolata'' was genetically differentiated from '' M. pansa'' and '' M. pottsiana''. In addition, about 70% of the genetic variation was partitioned within the populations rather than among them (30%). Three individuals from one population of ''M. petiolata'' were also genotyped in a study that developed microsatellite DNA markers for another species group of New Zealand ''Myosotis.'' The individuals of ''M. petiolata'' included had low genetic diversity.

Description

''Myosotis petiolata'' plants are rosettes. The rosette leaves have petioles that are 8–68 mm long. The rosette leaf blades are 3–35 mm long by 2–24 mm wide (length: width ratio 1.1–2.0: 1), usually narrowly obovate, obovate, broadly obovate, widest at or above the middle, with an obtuse and

mucronate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

apex. Both surfaces of the leaf are uniformly and densely covered in straight, appressed, antrorse (forward-facing) hairs. Each rosette has multiple ascending, unbranched or sometimes once-branched ebracteate inflorescences that are up to 470 mm long. The cauline leaves are similar to the rosette leaves, but become smaller. The flowers are 8–35 per inflorescence and each is borne on a short

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

without a bract. The calyx is 2–4 mm long at flowering and 3–5 mm long at fruiting, lobed to about three-quarters of its length, and densely covered in straight to curved, appressed to patent, antrorse hairs. The corolla is white and 5–10 mm in diameter, with a cylindrical tube, petals that are narrowly to broadly obovate or narrowly to broadly ovate, and small yellow scales alternating with the petals. The anthers are fully exserted. The four smooth, shiny, usually light to medium brown nutlets are 1.3–1.7 mm long by 0.8–1.0 mm wide and ovoid to broadly ovoid in shape. The pollen of ''Myosotis petiolata'' is unknown. The chromosome number of ''M. petiolata'' is unknown; an individual from the South Island previously identified as ''M. petiolata'' has a chromosome number of 2''n'' = 36, but South Island plants were excluded from ''Myosotis petiolata'' based on morphological and AFLP data.

Distribution and habitat

''Myosotis petiolata'' is currently only known to occur in the Te Waka Range, North Island, New Zealand in the Hawkes Bay region, at c. 900 m ASL, on limestone cliffs and bluffs''.'' It was previously collected in other nearby Hawkes Bay localities.

Conservation status

''Myosotis petiolata'' is listed as Threatened - Nationally Vulnerable in the most recent assessment (2017-2018) of the New Zealand Threatened Classification for plants. The qualifiers "DP" (Data Poor) and "OL" (One Location) are also attached to the assessment. ''Myosotis petiolata'' was featured on RNZ Critter of the Week as "one of the most endangered plants in the country".

Gallery

Some photos of leaves of cultivated plants. File:Myosotis_petiolata_leaves_1.jpg File:Myosotis_petiolata_leaves_2.jpg File:Myosotis_petiolata_leaves_3.jpg File:Myosotis_petiolata_leaves_4.jpg

References

External links

''Myosotis petiolata'' occurrence data from Australasian Virtual Herbarium
{{Taxonbar, from=Q17416948 petiolata Endemic flora of New Zealand Endangered flora of New Zealand Plants described in 1853