The New Zealand Plant Conservation Network

Species

Ranunculus ranceorum

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

Common Name(s)

None Known

Current Conservation Status

2012 - At Risk - Naturally Uncommon

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - At Risk - Naturally Uncommon
2004 - Range Restricted

Qualifiers

2012 - EF, RR, Sp

Authority

Ranunculus ranceorum de Lange

Family

Ranunculaceae

Flora Category

Vascular - Native

NVS Species Code

RANRAN

Structural Class

Dicotyledonous Herbs other than Composites

Synonyms

Ranunculus recens var. lacustris G.Simpson

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.

Features

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.

Flowering

December - April (depending on lake levels)

Flower Colours

Green,White

Fruiting

January - May (depending on lake levels)

Propagation Technique

Difficult. Should not be removed from the wild.

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.

Chromosome No.

2n = 32, 32 + f

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 29 Apr 2014