Myosotis arnoldii
Synonyms
None (first described in 1961)
Family
Boraginaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Dicotyledonous Herbs other than Composites
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | At Risk – Naturally Uncommon | Qualifiers: RR
Previous conservation statuses
2009 | At Risk – Naturally Uncommon
2004 | Range Restricted
Distribution
Endemic. South Island: Marlborough (Upper Ure (Waima) River, Chalk Range especially around Ben More; Nelson (Hoary Head)
Habitat
Myosotis arnoldii is a basicole known only from marble (North West Nelson) and limestone (Marlborough) rocks where it grows on sparsely vegetated cliff faces, ledges and associated rubble slopes.
Features
Stout, tufted, silvery grey perennial herb. Rosette-leaves 30-70 × 5-9 mm, linear-spathulate to oblanceolate, lamina merging into broad ill-defined petiole, tip subacute to obtuse; hairs alike on both surfaces, uniformly stiff, straight, closely appressed, strongly overlapping so at to completely cover leaf surface. Lateral branches erect, up to 180 mm long, leafless below cyme, lower internodes < leaves. Stem-leaves 15-25 × 2-5 mm, narrow-oblong, tip subacute; hairs like those of rosette-leaves. Cymes usually once forked, ebracteate, many-flowered, compact and 2-3 cm. long in flower, internodes and pedicels short. Calyx c.8 mm long, lobes c. 1/2 length, subacute; covered in short appressed hairs, these forming a close even silvery cover from which project long stiff hooked hairs that are most numerous towards the base. Corolla yellow, greenish to almost black, 8-10 mm diameter, tube 10-15 mm long, narrow-funnelform, > lobes, lobes c.3 × 3 mm, ± oblong; filaments broad, fixed between scales, about equal to anthers; anthers 2 mm long, wholly above scales; style at least 2× calyx, stigma capitate. Nutlet 2.6-3.1 × 1.3-1.5 mm, ovate-elliptic to elliptic, black.
Similar taxa
Myosotis arnoldii is like a stouter version of M. angustata from which it differs by its silvery leaves and stems, strongly overlapping leaf hairs which completely obscure the leaf epidermis, and by the typically dark greenish to almost black (rarely yellow) rather than white flowers. The flowers of Myosotis arnoldii are rather similar to those of M. macrantha which can show the same range of colours, they differ only in that the lobes of M. macrantha seem to spread more widely.
Flowering
October - January
Flower colours
Green, Yellow
Fruiting
December - May
Propagation technique
Somewhat difficult. Can be grown in a rock garden or alpine house but results vary. Like all indigenous Myosotis this species is sensitive to humidity and prone to fungal attacks from mildews and rusts in muggy weather.
Threats
Within its only known habitat this species is locally common and so far does not appear to be seriously threatened by weeds or browsing animals.
Etymology
myosotis: Mouse-eared
Where To Buy
Not commercially available
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange 1 February 2008. Description based on Allan (1961).
References and further reading
Allan, H.H. 1961: Flora of New Zealand. Vol. I. Goverment Printer, Wellington.
Citation
Please cite as: de Lange, P.J. (Year at time of access): Myosotis arnoldii Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/myosotis-arnoldii/ (Date website was queried)