Geranium socolateum
Family
Geraniaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Herbs - Dicotyledons 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.
2019 | Threatened – Nationally Critical
Brief description
A geranium of limestone habitats. Similar to Geranium brevicaule but differing by the more robust growth habit, longer petiole, larger leaves; these usually grey-green to light grey in colour and with a prominent brown margin up to 3.0 mm wide, and by the larger sepals and petals.
Distribution
Endemic. South Island, South Canterbury and North Otago.
Habitat
A species of open, sparsely vegetated, stable to semi-stable rocky limestone outcrops and associated colluvium, in a range of aspects, including open and sunny or sheltered and shaded. Also found growin amongst open prostrate shrubs and tussock-grasses.
Similar taxa
Geranium microphyllum sens. lat. (including plants from Subantarctic Islands, South Island and North Island) differs from G. socolateum by its longer, slender, trailing stems (up to 40 cm long), open, loose, straggly growth habit; by the lack of short and compact stems and by the leaves which are broader than long, thinner and distantly placed on trailing stems. Further the basal leaves are not persistent, the infloresences bear several flowers, and these have smaller diameters (8–10 mm across) with smaller petals (6.0–9.0 mm long). Geranium brevicaule differs from G. socolateum by its more compact growth habit, smaller leaves (usually up to 20 mm diameter), polymorphic leaf colour (green, bronze, purple) but not grey-green to light grey in colour, and by its smaller sepals (4.0–7.0 mm long) and petals (5.0–7.0 mm long).
Flowering
Not known
Flower colours
White
Fruiting
Not known
Propagation technique
Not known from cultivation.
Threats
Heenan & Molloy (2019) note that the total population of Geranium socolateum is fewer than 1000 individuals, with the species occurring in widely scattered populations comprising a few plants. The authors note severe habitat competition from naturalised plants, and the lack of suitable habitat for recruitment suggesting that populations are declining. They recommended that G. socolateum be assessed as ‘Threatened / Nationally Critical’ (Criterion “B” due to the small population with a moderate ongoing or predicted decline of 50–70%). Two subcriteria also apply: (B1) 250–1000 mature individuals and (B3) total area of occupancy ≤ 10 hectares (see Townsend et al. 2008).
Etymology
geranium: From the Greek geranos ‘crane’, the fruit of the plant resembling the head and beak of this bird, hence the common name cranesbill.
socolateum: Chocolate i.e. ‘chocolate’ colouration
Attribution
Fact sheet prepared by P.J. de Lange (6 September 2019). Description from Heenan & Molloy (2019).
References and further reading
Heenan, P.B.; Molloy, B.P.J. 2019: Five new and Nationally Threatened taxa of Brachyscome, Cardamine, Convolvulus, Geranium and Ranunculus obligate to vulnerable limestone habitats, eastern South Island, New Zealand. Phytotaxa 415(1): 32-48.
Townsend, A.J.; de Lange, P.J.; Norton, D.A.; Molloy, J.; Miskelly, C.; Duffy, C. 2008: The New Zealand threat classification system manual. Department of Conservation, Wellington, 35 pp.
Citation
Please cite as: de Lange, P.J. (Year at time of access): Geranium socolateum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/geranium-socolateum/ (Date website was queried)