The New Zealand Plant Conservation Network

Species

Cardamine lacustris

Etymology

Cardamine: From the Greek name kárdamon, referring to an Indian spice
lacustris: From the Latin lacus 'lake', meaning growing beside a lake

Common Name(s)

Iti

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 - Sp
2009 - EF

Authority

Cardamine lacustris (Garn.-Jones et P.N.Johnson) Heenan

Family

Brassicaceae

Flora Category

Vascular - Native

NVS Species Code

CARLCT

Structural Class

Dicotyledonous Herbs other than Composites

Synonyms

Iti lacustris Garn.-Jones et P.N.Johnson

Distribution

Endemic. New Zealand: South Island (Lakes Manapouri, Te Anau and also around small tarns in the eastern part of Fiordland)

Habitat

A lake and tarn dwelling plant. It mostly grows on gently-shelving slopes usually within a sparse turf of other plants where a thin cover of silt or fine sand is lodged among firm and stable cobbles or gravels. In its main lake habitats these are sites which tend to be neither the most sheltered nor the most exposed available, but are subject to moderate wave action and the resultant periodic disturbance of sediments.

Features

Minute ephemeral or annual rosette herb. Stems on young plants very short, on older plants lateral, ascending at first, later prostrate, geniculate, rooting regularly, up to 50 mm long, reaching 0.8-2.0 mm diameter, glabrous or sometimes with sparse, fine, slightly recurved hairs. Leaves glabrous, or with sparse simple hairs on petiole, slightly glossy, dull green or tinged purplish-grey, in rosettes and clustered on stems. Early rosette leaves entire, linear-spathulate; later rosette and cauline leaves pinnatifid, 20-50 mm long; petiole 2-12 mm long, 0.5-1.0 mm wide; terminal lobe narrow-spathulate, 2-5 mm broad; lateral lobes narrowly oblong-spathulate, 4-10 mm long, sometimes single or in uneven numbers, but usually in l-3 subopposite pairs. Peduncle glabrous, 1-2 mm long, reaching 2-5 mm long at fruiting. Sepals suberect, oblong, glabrous, green with narrow pale margins, 1.5-2.0 × 0.6-1.0 mm. Petals white, suberect, oblong- to obovate-spathulate, obtuse, 1.8-2.5 × 0.8-1.2 mm, weakly clawed; limb spreading. Stamens suberect; median stamens usually 2, rarely 4, 1.6-2.0 mm long; lateral stamens 1.0-1.5 mm long. Ovary ellipsoid, 1.0-1.6 mm long; stigma sessile, 0.4 mm diameter; locules each with 5-8 ovules. Silicle elliptic to oblong, l.0-3.5 × 1.0-1.7 mm; valves pale straw coloured, thin, convex, glabrous, not veined or with 1 weak vein. Seeds c.5-8 in one row in each locule, pale to reddish brown, oblong, c.1 mm long.

Similar Taxa

Cardamine lacustris is probably closely allied to an undescribed Cardamine (known by the tag name - tarn), which inhabits the moist margins of tarns, kettles, and streams from Marlborough south through inland Canterbury to Otago and northern Southland. This unnamed cress has a similar over all size and leaf shape to C. lacustris but differs by the long peduncles and a narrow, explosively dehiscent silique 10-15 times as long as its width.

Flowering

October - May (depends on water levels)

Flower Colours

White

Fruiting

November - July (depends on water levels)

Propagation Technique

Easily grown from fresh seed. Plants do best kept in a small pot partially submerged in water. Not that attractive for the garden but the leaves are edible and it could be used in cress sandwiches.

Threats

Apparently not threatened but not that common either. Its presence is dictated by seasonal water levels. Some populations around Lake Manapuri and Te Anau may be threatened. Further research is required.

Chromosome No.

2n = 48

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Life Cycle and Dispersal

Seeds are dispersed by ballistic projection, water and attachment (Thorsen et al., 2009).

This page last updated on 25 May 2014