Nasturtium microphyllum
Common names
one-rowed watercress
Biostatus
Exotic
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
A bright green, robust, creeping or upright herb that has small white flowers in spring through summer, and is found along the margins of slow flowing shallow waters. Leaves have a distinctive peppery smell when crushed.
Flower colours
White
Detailed description
Perennial stoloniferous herb. Stems trailing, glabrous, to several m long. Leaves glabrous, all similar, but becoming smaller near inflorescence. Pinnate, petiolate, 2-10-(25) x 1-5 cm; basal auricles very small; leaflets rounded, ovate; margins entire or sinuate. Pedicels glabrous, slender, erecto-patent, spreading to deflexed at fruiting, (8)-12-20-(30) mm long. Sepals 2.5-3.5 x 1 mm. Petals white, (4)-5-6 x 1.5-2.5 mm. Silique glabrous, narrow-oblong to linear, curved, (10)-15-25-(30) x c.1.5 mm; valves with distinct midrib, at least below; style c. 1 mm long. Seeds in ± 1 row per locule, brown, c. 1mm long, coarsely reticulate with 100-150 polygonal depressions per face.
Similar taxa
Very similar to N. officinale, but the flowers of N. microphyllum are larger, capsules are longer and more slender, and the seeds are in one row and with more finely pitted surfaces. The leaves of N. microphyllum turn brown/purple in autumn/winter.
Distribution
Common throughout New Zealand.
Habitat
Margins of slow moving rivers, streams, ditches and drains.
Conservation status
Not applicable
Detailed taxonomy
Family
Synonyms
Rorippa microphylla (Boenn.) N. Hylander
Ecology
Flowering
August - June
Fruiting
Summer-autumn
Year naturalised
1954
Origin
Europe
Reason for introduction
Culinary herb.
Life cycle and dispersal
Stem fragmentation and seed.
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
Etymology
microphyllum: Small leaf
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.
NASMIC
Referencing and citations
References and further reading
Popay et al (2010). An illustrated guide to common weeds of New Zealand, third edition. NZ Plant Protection Society Inc, 416pp.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Aston, H (1977). Aquatic plants of Australia. Melbourne University Press, 367pp.
Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. (1988). Flora of New Zealand Volume 4: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Webb et al. (1988).
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.