None (first described in 1961)
Vascular – Native
Herbs - Dicotyledons other than Composites
Current conservation status
The threat classification 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) – more information about this can be found on the NZTCS website 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. Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – a suggested threat classification status has not been assessed by the NZTCS panel.
2017 | At Risk – Naturally Uncommon | Qualifiers: DP, RR
Previous conservation statuses
2012 | At Risk – Naturally Uncommon | Qualifiers: RR
2009 | At Risk – Naturally Uncommon
2004 | Range Restricted
Endemic. South Island: Marlborough (Upper Ure (Waima) River, Chalk Range especially around Ben More; Nelson (Hoary Head)
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.
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.
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.
October - January
December - May
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.
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.
Where To Buy
Not commercially available
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.
NZPCN Fact Sheet 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)