Ranunculus paucifolius
Common names
Castle Hill buttercup
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
Yellow
Detailed description
Robust, summer-green, glabrous herb, up to 100 mm high. Rhizome up to 180 mm long, stout, sometimes branched, with thick vertical fibres; stock stout, erect or ascending, up to 40 mm long. Rosette leaves 1–20; lamina 20–70 × 20–60 mm, spreading, broadly reniform or broadly orbicular, grey to grey-green, often purplish, nearly entire or divided into 3–5 primary segments, segments usually shallow divided although occasionally up to 3/4 lamina depth, overlapping, margin finely dentate, base cuneate to subreniform; petiole 20–60 × 1.5–4.5 mm; sheath at base, broad. Scape 10–20 mm long, solitary, stout, naked, 1-flowered; reflexed at maturity. Flowers 20–50 mm diameter. Sepals 5, 8–11 × 4–6 mm, pale yellow, deflexed, ovate-oblong, apex subacute. Petals 5–10, 15–20 × 6–13 mm, golden yellow, broadly obovate, obovate to oblanceolate, apex obtuse to rounded, nectary 1–3 simple pits. Stamens 23–38; filament 3.5–5.0 mm long; anthers 1.8–2.2 mm long. Carpels 17–35. Achenes 3.0–4.2 mm long, brown; beak curved, laterally compressed, tapering toward apex.
Similar taxa
Most similar to R. crithmifolius from which it is distinguished by the leaves having three or occasionally five shallow and usually overlapping lobes that are rarely dissected to the base, the margins are finely and sharply toothed, and the base truncate to cuneate. In contrast, R. crithmifolius has leaves that are trifoliolate, each lobe is further divided for about one third of the depth, and the margins are more coarsely and deeply toothed to crenate.
Distribution
Endemic. New Zealand: South Island (Canterbury)
Habitat
Montane. Restricted to limestone colluvium and tallus in a gently sloping basin.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Threatened – Nationally Critical | Qualifiers: CD, OL, RF
Threats
A limestone endemic that is naturally restricted to a very small geographical area. Plants are vulnerable to browse damage from rabbits, hares and sheep, weeds are a constant threat, and seedlings are rarely seen.
Detailed taxonomy
Family
Ranunculaceae
Synonyms
Ranunculus crithmifolius subsp. pauciflorus (Kirk) F.J.F.Fisher; Ranunculus crithmifolius Hook.f. pro parte
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–December
Fruiting
November–January
Propagation technique
Difficult. Should not be removed from the wild.
Other information
Where To Buy
Not Commercially Available
Etymology
ranunculus: From the Latin ‘rana’ frog, meaning little frog and probably refers to the plants typical marshy habit where frogs abound
paucifolius: Few leaves
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
RANPAU
Chromosome number
2n = 48
Previous conservation statuses
2017 | Threatened – Nationally Critical | Qualifiers: CD, DP, OL
2012 | Threatened – Nationally Critical | Qualifiers: CD, OL
2009 | Threatened – Nationally Critical | Qualifiers: CD, OL
2004 | Not Threatened
Referencing and citations
Attribution
Description based on Kirk (1899), Allan (1961), Fisher (1965) and herbarium specimens.
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.