Rorippa sylvestris
Common name
creeping yellow cress
Synonyms
Tall herb, up to 70 cm tall, with various shaped leaves, lobed, with 2 to 5 pairs of leaflets, the uppermost with very narrow segments with coarsely toothed margins, flowers are yellow c. 5 mm across in large flower heads at the top of the stem.
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.
RORSYL
Conservation status
Not applicable
Distribution
Locally common in both islands.
Habitat
Margins of water bodies and cultivation and wet pasture weed.
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).
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Features
Glabrous perennial rhizomatous herb. Stems erect, often flexuous, 30-70 cm tall. Lvs variable in shape; margins toothed. Rosette lvs petiolate, auriculate at base, deeply pinnatifid, 4-10-(25) × 2-4 cm. Middle and upper lvs smaller, 1-2-pinnatifid, linear to ovate; lobes narrow-lanceolate to linear, entire or toothed; basal auricles present. Pedicels erecto-patent at flowering, spreading at fruiting, 5-15 mm long. Sepals 2-2.5 mm long. Petals yellow, (3)-4-5 mm long. Silique glabrous, linear, curved, 10-15 × 1-1.5 mm, but often not or poorly developed; valves with median vein weak or 0; style c. 0.5 mm long. Seeds brown, c. 0.6 mm long, finely colliculate, in 2 rows per locule.
Similar taxa
Similar to the introduced tall yellow cress (R. amphibia) and the native poniu (R. palustris) but petals being > 2x length of the petals (unlike poniu) and fruit being sausage shaped rather than oval with peduncles < 2x the length of the fruit (unlike tall yellow cress).
Flowering
October to March
Flower colours
Yellow
Fruiting
November to March
Life cycle
Seed and rhizomes dispersed by water or contaminated machinery.
Year naturalised
1952
Origin
Temperate Eurasia
Reason for introduction
Unknown, seed or soil contaminant
Control techniques
Can be controlled manually, mechanically or herbicidally depending on situation.
Etymology
rorippa: A latinized form of Rorippen, a Saxon vernacular name used by Euricius Cordus
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Webb et al. (1988).
References and further reading
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.
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.