FOOL'S WATERCRESS

FOOL'S WATER-CRESS

Apium nodiflorum

Carrot Family [Apiaceae]

month8jun month8june month8jul month8july month8aug month8sep month8sept

status
statusZnative
flower
flower8white
inner
inner8pink
morph
morph8hemizygo
petals
petalsZ5
type
typeZumbel
stem
stem8angular
stem
stem8ribbed
stem
stem8hollow
toxicity
toxicityZlowish

23rd July 2016, dunes, Ainsdale, Sefton Coast. Photo: © RWD
In shallow fresh-water amidst Common Club-rush, Water Mint, Tubular Water-dropwort and others.


23rd July 2016, dunes, Ainsdale, Sefton Coast. Photo: © RWD
Fool's Watercress is the one with 5-8 umbelettes of white flowers and the larger simply-pinnate leaves.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
In a very shady farmers stream. Lowest leaves larger than upper leaves. Leaves singly-pinnate with usually between 2 and 4 pairs of opposite leaflets (but can be as low as 1 pair or as high as 6 pairs. Umbels smallish and compound.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Umbels with between 3 and 15 umbellets. All have hermaphroditic (bisexual) flowers.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Seemingly, umbels are frequently found in the 'armpits' of the plant.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Flowers not yet open on this umbel, enabling us to more clearly see it. Bracts (on the umbel) are usually absent, but there can be up to 2. The rays are 1-2cm long (but can be as short as 3mm) whilst the peduncles (the individual stalks of the flowers) are either very much shorter or almost absent. Bracteoles (bracts around the umbellets) number between 4-7.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Note the short bract paler-green bract along the topmost of the leftmost stem branch.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Unequal length bracteoles in whorls just beneath each umbellet. The rays are scabrid (with very short rough-to-the-touch hairs)


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Flowers with 5 white slightly asymmetrically arranged petals.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Rear view of whorl of bracteoles beneath each umbellet. Stem variously angular or ridged or both.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Each flower with 5 petals, one of which can be slightly longer than the others.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
A whorl of bracteoles beneath an umbellet. You can just about make ot some individual but short peduncles (flower stalks).


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
The brown things beneath some flowers are the fruits beginning to form as the flowers drop their petals.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
With 5 white petals and 5 white filaments bearing anthers which are pinkish-red turning dark-brown.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
Flowers in centre with petals yet to unfold.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
A double-barrelled fruit in the centre.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Petals all gone; turning to fruit.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
The fruits are green at first.


5th Aug 2016, a shallow stream, south of Wrexham. Photo: © RWD
The double-barrelled fruit has a stylopodium atop (not all umbellifers do). Emerging from the whitish stylopodium are two white diverging styles. When ripe (they are not yet in these photos) the fruit are brown, 2-2.5mm long, ovoidal, laterally compressed and smooth


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Stems hollow.


23rd July 2016, a pond, Ainsdale dunes, Sefton Coast. Photo: © RWD
Leaves with teeth.


Not to be semantically confused with : Fool's Parsley (Aethusa cynapium) [a plant in the same umbellifer family with similar name]

Easily mistaken for : some growth forms (those which are dwarfish with procumbent stems) look very much like Creeping Marshwort (Apium repens) but that now only occurs in South Essex, Berkshire and Oxfordshire.

Can be mistaken for Lesser Water-Parsnip (Berula erecta) which also likes to grow in similar damp places but that usually has several (4-7) bracts just beneath the umbel and which are tri-pointed (whereas in Fool's Watercress bracts are usually absent, or with just one, or 2).

Can also be mistaken for Watercress (Rorippa nasturtium-aquaticum) but that is a Brassicaceae and not an umbellifer which tastes differently, has solid stems (rather than the hollow of Fool's Watercress) with flowers with only 4 petals, and with totally different fruits.

Hybridizes with :

  • Creeping Marshwort (Apium repens) to form Apium longipedunculatum (?) which is more procumbent and extensively rooting than Fools's Watercress with which it occurs in Cambridgeshire, SE Yorkshire and Fife.
  • Lesser Marshwort (Apium inundatum) to form Apium moorei which has but 1-3 rays and is sterile but occurs with both parents scattered over most of Ireland and the Outer Hebrides.

Grows in wet streams, ditches, pond-edges, in marshes, beside lakes and rivers. It is native and common in the British Isles.

The essential oil from the aerial parts of the plant may contain both Myriscticin and Dillapiol, the two frequently occurring together because the latter results from enzymatic methoxylation of the former. These should make the leaves poisonous, although there are reports of folk eating it in mistake for Watercress (Nasturtium officinale) and getting away with it. The quantity of toxins probably depends upon the soil, what time of year it is harvested, the number and type of pathogens it encounters, and on the weather during their growing season.


  Apium nodiflorum  ⇐ Global Aspect ⇒ Apiaceae  

Distribution
 family8Carrot family8Apiaceae

 BSBI maps
genus8Apium
Apium
(Marshworts)

FOOL'S WATERCRESS

FOOL'S WATER-CRESS

Apium nodiflorum

Carrot Family [Apiaceae]