Rorippa divaricata
Common names
New Zealand watercress, matangoa
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White
Detailed description
Annual to perennial herb (depending on local growing conditions), 0.3-2 m tall, arising from stout taproot. Basal stem one (or more), erect to decumbent, glabrescent, woody, purple red when mature, somewhat angled. Leaves green, yellow-green, dark green or purple-green, margins sinuate, dentate to deeply toothed. Basal leaves petiolate, petiole broadly winged, grading into deflexed amplexicaul leaf lobes; lamina 30-160 x 20-80 mm, pinnatifid. Mid cauline leaves similar but smaller, upper cauline leaves much smaller, linear-lanceolate, simple, basally cuneately narrowed or amplexicaul. Inflorescence a complex, heavily branched raceme. Racemes 50-200 mm long. Pedicels 5-20 mm long at flowering, erecto-patent, spreading to deflexed at fruiting. Sepals 2-3 mm long. Petals white 2-3 mm long. Fruit a dark green to purple-green silique, 10-40 x 1-2 mm, spreading, linear, more or less terete, shallowly grooved along suture. Style remnant c.2 mm long. Seeds orange to red-brown, c.1 mm diam., extremely sticky when fresh.
Similar taxa
None.
Distribution
Endemic. Known from the Kermadec, Three Kings, North, South and Chatham Islands. It has not been seen on the Kermadecs for over 100 years but is still present on the Three Kings, Poor Knights and other Hauraki Gulf Islands. In the North Island it has been recorded recently from Kawhia, Hicks Bay and the Rotorua Lakes district. In the South Island it is known from and in the vicinity of the Abel Tasman National Park. On the Chatham Islands it has been collected once in 1985 and not reliably reported since.
Habitat
A species of recently disturbed ground. Usually found in or near clearings, on recent slips or on track margins. Often on lake and river margins. Plants may also grow within active petrel colonies, often around burrow entrances. This species seems to do best in dappled light, and is often found in forested habitats. It has also been found in pine plantations.
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 Vulnerable | Qualifiers: DPS, DPT, EF, PD, PF
Threats
Weed competition is a major threat. Trampling, vegetation succession and vegetation clearance will also threatened populations. Plants are prone to drought. Browsing animals (possums, rodents, stock and feral pigs) and exotic insect pests (particularly cabbage white butterfly) are also significant threats.
Detailed taxonomy
Family
Brassicaceae
Synonyms
Arabis gigantea Hook.f., Cardamine divaricata Hook.f., C. stylosa DC, Nasturtium stylosum (DC) Schulz, Rorippa stylosa (DC.) Allan, R. gigantea (Hook.f.) Garn.-Jones
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
Spring (can flower from October to February)
Fruiting
Summer (can fruit from October to May)
Propagation technique
Easy from fresh seed. A very fast growing and weedy species which can become invasive.
Other information
Cultivation
Occasionally available from specialist native plant nurseries.
Cultural Use/Importance
The young leaves, stems, flowers, seed capsules, are delicately and pleasantly flavoured, and together with Cooks scurvy grass (Lepidium oleraceum Sparrman), celery (Apium prostratum subsp. prostratum var. filiforme (A.Rich) Kirk, and native spinach (Tetragonia tetragonoides (Pall.) Kuntze) make a great indigenous summer salad.
Etymology
rorippa: A latinized form of Rorippen, a Saxon vernacular name used by Euricius Cordus
divaricata: Spreading or branching at wide angles
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.
RORDIV
Chromosome number
2n = 48
Previous conservation statuses
2017 | Threatened – Nationally Vulnerable | Qualifiers: DP, EF
2012 | Threatened – Nationally Vulnerable | Qualifiers: EF
2009 | Threatened – Nationally Vulnerable | Qualifiers: EF
2004 | Threatened – Nationally Endangered
Referencing and citations
References and further reading
de Lange, P.J.; Heenan, P.B.; Norton, D.A.; Rolfe, J.R.; Sawyer, J.W.D. 2010: Threatened Plants of New Zealand. Canterbury University Press, Christchurch.
Attribution
Fact Sheet Prepared by P.J. de Lange (1 November 2009). Description by P.J. de Lange subsequently published in de Lange et al (2010).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Rorippa divaricata Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/rorippa-divaricata/ (Date website was queried)