WATER-CRESS

Nasturtium officinale

formerly: Rorippa nasturtium-aquaticum
Cabbage Family [Brassicaceae]

month8may month8jun month8june month8jul month8july month8aug month8sep month8sept month8oct

status
statusZnative
 
flower
flower8white
 
inner
inner8yellow
 
morph
morph8actino
 
petals
petalsZ4
 
stem
stem8ribbed
 
stem
stem8hollow
hollow

2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Very much like Narrow-Fruited Water-cress from afar.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Grows erect or sprawling to 60cm.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Leaves are pinnate and green all year round and in the case of var. siifolium could be mistaken for Fool's-Water-cress, a poisonous umbellifer (but that has five petals rather than four).


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Sprawling onto the walkway.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Before all the flower buds have opened there is an annular ring of white flowers surrounding a central area of light-green buds. Leaves edible.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Flowers white with four petals.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Has four stamens tipped with cream-coloured anthers that bear yellow pollen. Seed pods with stigma still attached growing out of some of the flowers.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
The seed pods are still cylindrical (as in Narrow-Fruited Water-cress), but they contain two rows of seeds (as opposed to only one row), and are shorter, fatter and more knobbly than those of Narrow-Fruited Water-cress)


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
According to Fitter Fitter and Blamey, the petals narrow gradually towards the centre (whereas with Narrow-Fruited Water-cress they get narrow abruptly). Note purple stamens (normally hidden deep within the flower) remaining on one of the growing seed pods (left).


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Un-like Narrow-Fruited Water-cress the stamens curl inwards (rather than splay outwards).


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Pods shorter, fatter and knobblier than those of Narrow-Fruited Water-cress. Stems ridged here.


2nd June 2012, settling pond, T&M canal, Kidsgrove Photo: © RWD
Leaves pinnate. Stems can be angular or ridged in places.


Not to be semantically confused with : Fool's-Water-cress (Apium nodiflorum) [a poisonous plant with similar name which belongs to the Carrot Family (Apiaceae) and which looks like the variety of Water-cress called var. siifolium].

Easily mistaken for : Narrow-Fruited Water-cress, see photo captions.

Easily mis-identified as : Fool's-Water-cress (Apium nodiflorum)

Hybridizes with : Narrow-Fruited Water-cress (Nasturtium microphyllum) to produce Nasturtium × sterile which has sterile and misshapen seed pods.

The old genus name (Rorippa) is not to be confused with : the Rorippa genus of Yellow-cresses such as Creeping Yellow-Cress.

An aquatic plant well known as one used as a salad. It is perennial and the leaves are green all year round. Grows in flowing shallow freshwater or on very wet mud and in slow-flowing streams. It is hairless and has hollow stems.

A GLUCOSINOLATE


On of the most widely distributed of all the Glucosinolates in the Cabbage Family (Brassicaceae). Gluconasturtiin, like all glucosinolates, is perfectly harmless to ingest until the plant cells that contain it are damaged, such as occurs when it is chewed in the mouth or attacked by an insect plant pest. It is then that the glucosinolate is acted upon by the enzyme myrosinase (which is also in the cell). The myrosinase detaches the glucose unit from the rest of the molecule to produce an intermediate compound which almost spontaneously rearranges itself from the N-O-HSO3 unit to the isothiocyanategroup -N=C=S which remains bonded to the organic group to become a mustard oil. It is the mustard oil, PhenylEthyl IsoThioCyanate that is toxic, and can also burn the skin.

Gluconasturtiin is also found in Horseradish (Armorcia rusticana) along with another glucosinolate Sinigrin. Both taste bitter in the mouth.


  Nasturtium officinale  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae

 BSBI maps
genus8Nasturtium
Nasturtium
(Water-Cresses)

WATER-CRESS

Nasturtium officinale

formerly: Rorippa nasturtium-aquaticum
Cabbage Family [Brassicaceae]