Ranunculus ranceorum
Biostatus
Native
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
Green, White
Detailed description
Annual or short-lived perennial herb of lake shore marginal turf communities, forming diminutive rosettes up to 40 mm diam. Rarely solitary, frequently forming crowded patches comprising numerous smaller daughter offsets and seedlings. Rootstock stout, 2-4 mm diam., ascending, ± cylindrical, white, fleshy to succulent, apex covered with rotted, fibrous petiolar remnants, deeply and firmly rooted, branching at surface to form 1 or more rosettes. Petiole (5-)10(-20) mm long, fleshy to succulent, bronze green to bright green in exposed portion otherwise white, base grooved and broadly sheathing, otherwise weakly concave to flat or slightly convex on upper surface, margins usually bearing sparse, scattered, white, cobwebby hairs. Adult leaves (2.5-)9.0(-12.0) × (2.0-)7.0(-10.8), bright green, bronze green to dark green or dark green with brown veins, ± glossy, fleshy, broadly rhomboid, deltoid, to broadly ovate, lamina entire in seedlings and in initial emergent adult growth, otherwise 3-lobed to almost 3-foliate; lobe segments broad, concave, mostly entire, margins often finely though sparsely cobwebby hairy, glabrate. Peduncles initially sessile (sometimes remaining that way), or very short, up to 6 mm long, usually elongating slightly on fruiting, fleshy, ± succulent, up to 0.9 mm diam., white to green, glabrescent, bearing 2-4(-6) narrowly to broadly deltoid, entire, bracts. Flowers 2.5-7.0 mm diam., usually solitary or in scarcely separated pairst; sepals 5, caducous, 1.5-1.8(-2.0) mm long, green to greenish-white, broadly ovate to orbicular; petals 5 or absent, 0.8-1.3 mm, glossy yellow at apex only, ovate to almost spathulate, apex broadly obtuse to rounded; nectary 1, at base of petal, covered by an ovate scale, obscured by carpels; stamens 6-15; receptacle glabrous. Achenes 8-20, body 0.6-1.2 mm long, pale cream-brown, oblong to obovoid, convex on ventral and dorsal sides, cuneate at base; in cross section broadly ellipsoid; ventral margin rounded in upper 2/3 ± flattened to flat in basal 1/3, without any obvious ridge; dorsal surface rounded, prominently ridged, ridge hyaline, tapering toward beak, thickening toward base; surface glossy when fresh, distinctly punctuate, otherwise bearing irregular somewhat diffuse patches of caducous hairs; beak 0.05-0.10(-0.15) mm long, straight, weakly curved or hooked toward ventral side, often withered to a short black tipped stub, laterally compressed.
Similar taxa
R. ranceorum differs from R. recens Kirk by its smaller size, leaf, flower, achene size and shape, by its chromosome number, and habitat preferences. R. maculatus Cockayne et Allan, also a lake/tarn marginal turf plant is similar. It has a taller habit (up to 50 mm tall), usually with larger, elliptic, obovate to orbicular, glossy green dark brown blotched leaves, oblong-obovate petals, and longer purple-tipped achenes.
Distribution
Endemic. South Island, Lakes Te Anau, Manapouri and possibly Te Au.
Habitat
A species of lake side marginal turf communities where it occupies sites frequently flooded by up to 1.5 m of water for long parts of the year.
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 | At Risk – Naturally Uncommon | Qualifiers: EF, RR, Sp
Threats
A naturally uncommon plant of seasonal habitats. It is not clear if plants die after flooding or persist in an aquatic form until water levels recede. Although it is regarded here as a Naturally Uncommon/Range Restricted plant, its survival requires careful management of water levels at Lake Manapouri which is administered as an hydroelectric lake.
Detailed taxonomy
Family
Ranunculaceae
Synonyms
Ranunculus recens var. lacustris G.Simpson
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December - April (depending on lake levels)
Fruiting
January - May (depending on lake levels)
Propagation technique
Difficult. Should not be removed from the wild.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
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
ranceorum: Named after Brian and Chris Rance, botanists from Southland
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.
RANRAN
Chromosome number
2n = 32, 32 + f
Previous conservation statuses
2017 | At Risk – Naturally Uncommon | Qualifiers: EF, RR, Sp
2012 | At Risk – Naturally Uncommon | Qualifiers: EF, RR, Sp
2009 | At Risk – Naturally Uncommon
2004 | Range Restricted
Referencing and citations
References and further reading
de Lange, P.J.; Murray, B.G. 2008: Ranunculus ranceorum, a new name and rank for Ranunculus recens var. lacustris G.Simpson, an elusive, rarely seen buttercup of the Fiordland lakes, South Island, New Zealand. New Zealand Journal of Botany 46: 1-11.
Attribution
Fact Sheet prepared for the NZPCN by P.J. de Lange 14 April 2006. Description from de Lange & Murray (2008).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Ranunculus ranceorum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/ranunculus-ranceorum/ (Date website was queried)