Nasturtium officinale
Common name
Watercress
Family
Brassicaceae
Flora category
Vascular – Exotic
Structural class
Herbs - Dicotyledons other than Composites
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.
NASOFF
Brief 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.
Distribution
Common throughout New Zealand.
Habitat
Aquatic: Emergent. Marginal aquatic plant, can grow in water up to 6m in depth (Waikoropupu springs)
Features
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 small; leaflets rounded, ovate; margins entire or sinuate. Pedicels glabrous, slender, erecto-patent, spreading to deflexed at fruiting, (5)-10-15-(18) mm long (very rarely to 30 mm). Sepals 1.5-2.5 x 0.7-1.5 mm. Petals white, (3)-4-6 x (1)-1.5-2.5 mm. Silique glabrous, narrow-oblong, curved, (8)-12-15-(18) x 2-2.5 mm; valves with distinct midrib, at least below; style c. 1 mm long. Seeds distinctly in 2 rows per locule, brown, c. 1mm long, coarsely reticulate with 20-50 polygonal depressions per face.
Similar taxa
Very similar to N. microphyllum, but differs in its seed surface and also tends to have smaller flowers, shorter pedicels and broader siliques.
Flowering
August - May
Flower colours
White
Fruiting
(August)-November-February-(May)
Life cycle
Perennial, reproduces by stem fragmentation and see
Year naturalised
1852
Origin
Eurasia, Northern Africa
Reason for introduction
Culinary herb (Healy 1962)
Etymology
officinale: From the Latin officina shortened from opificina which originally meant ‘workshop’ but later came to mean a monastic storeroom, herb-room or pharmacy. Refers to the plant’s medicinal value.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Webb et al., (1988).
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.
Healy, A.J. (1998). Some consequences of the introduction of watercress by the French at Akaroa. Canterbury Botanical Society 33: 9-10.
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.