Nasturtium officinale (Watercress)

Plant Info
Also known as: Small-leaved Water-cress
Genus:Nasturtium
Family:Brassicaceae (Mustard)
Life cycle:perennial
Origin:Europe
Status:
  • Invasive - ERADICATE!
Habitat:part shade, sun; cool flowing streams and springs
Bloom season:April - July
Plant height:4 to 15 inches
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 4-petals Cluster type: raceme

[photo of flowers] Elongating racemes at the ends of many branching stems, with blooming flowers clustered at the tip. Flowers are ¼ to 3/8 inch across with 4 rounded white petals, 6 yellowish stamens, a short central style, and a purplish green ovary.

Leaves and stems: Leaf attachment: alternate Leaf type: compound

[photo of leaves] Leaves are 2 to 4 inches long, ¾ to 1½ inches wide, compound in groups of 3 to 9. Leaflets are oval to lance-shaped with irregular edging, typically rounded at both ends, the terminal leaflet rather larger than the rest and may be nearly round in shape. Stems and leaves are hairless. Stems float on the surface of the water or spraw across mud, rooting freely at the nodes.

Fruit:

Fruit is a slender pod, ½ to 1¼ inches long with a short abrupt beak, straight to slightly curved, spreading to somewhat ascending. Seeds are oval, reddish brown, arranged in 2 rows.

Notes:

Formerly known as Rorippa nasturtium-aquaticum, this is the same Watercress found in your local grocer's produce department. A widespread and problematic invasive of clear streams, springs and brooks, it can rapidly spread out on the surface of the water choking out natives. The stems and leaves are crisp and can be used as a salad with a pungent radish flavor. I do like harvesting it wild, but cleaning off aquatic insects and spiders is a chore as well as running the risk of beaver-fever (girhardia), or ingesting the toxins in our polluted waters. When not fruiting it is virtually indistinguishable from Nasturtium microphyllum (Rorippa microphylla), also found in Minnesota. N. microphyllum has seeds 1 row, and is aptly commonly called One-row Yellowcress.

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More photos

Photos by K. Chayka taken at Whitewater Wildlife Management Area. Photos courtesy Peter M. Dziuk taken in Dakota, Winona and Washington counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: gordon in st cloud
on: 2012-01-26 13:37:22

do you or do you know where i could get a list of local gardens or gardeners where i could go to pick my own water cress? when i was young my grandparents had a cabin on the mississippi where the property had 3 fresh water springs and the water cress was abundant and available year round. i really miss being able to use it in recipies. any help would be much appreciated thank you

Posted by: K. Chayka
on: 2012-01-26 17:10:49

Watercress, an invasive species, is choking streams in the Whitewater area of Winona county. Feel free to go down there and harvest all you want. ;)

If any gardens or garden clubs are promoting this weed, it would be better to educate them as to the invasive nature of this pest, and stop its spread before it does more damage to local ecosystems.

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