LESSER MARSHWORT

Apium inundatum

Carrot Family [Apiaceae]

month8jul month8july month8aug

status
statusZnative		 flower
flower8white		 inner
inner8red		 morph
morph8actino		 petals
petalsZ5		 type
typeZumbel		 stem
stem8round		 stem
stem8hollow		 sex
sexZbisexual

28th July 2013, New Forest, Hampshire. Photo: © Dawn Nelson
This plant has 2 different kinds of leaves the shape of which differ depending upon whether they are submerged or are above water. However, here the water has evaporated showing the previously submerged leaves. This specimen must be youngish, as it has not yet grown the higher differently-shaped leaves which would be above water level.


28th July 2013, New Forest, Hampshire. Photo: © Dawn Nelson
The stems are hollow (probably all along their length) and wider near the base. The leaves long and narrow, doubly-pinnate, sometimes triply-pinnate with either 2 or 3 leaflets at the ends.


28th July 2013, New Forest, Hampshire. Photo: © Dawn Nelson
The flowers, which are held above water-level (when there is any water...) are tiny, white with 5 red anthers (not discernible on these specimens) and about 2mm across with 5 petals. Near the flowers are some leaves normally held above water-level (when there is dome) and they have wider leaflets which are in threes. The leaflets are c. 5mm long.


28th July 2013, New Forest, Hampshire. Photo: © Dawn Nelson
A confusing profusion of stems (some of which may be other plants?) and a few leaflets north of centre.

Not to be confused with : Creeping Marshwort (Apium repens) [a plant with similar name in the same genus and with which it can hybridise, but is a rare ]

Fool's-Water-cress (Apium nodiflorum) is also in the same Genus, Apium. The Genus Apium has since been renamed Helosciadium but your Author cannot keep up with these constant changes to Genus, so he is ignoring it. The only plant left under the Apium genus is Wild Celery (Apium graveolens).

Hybridizes with :

  • Fool's-Water-cress (Apium nodiflorum) to produce Apium × moorei which is found in the Outer Hebrides but might be extinct in Central England.

It is to be found mostly in the West of the UK but there are large pockets of it in the Shetlands, around London area.

The fruits of it are well ridged, between 2.5 to 3mm long, flattened-oval and ribbed. It is to be found in or besides shallow water marshes and marshes. The umbels are on short stalks with between 2 to a maximum of 4 short rays without bracts. There are between 3 and 6 bracteoles bearing a white flower about 2mm across.

  Apium inundatum  ⇐ Global Aspect ⇒ Apiaceae  

Distribution
family8Carrot family8Apiaceae
 BSBI maps
genus8Apium
Apium
(Marshworts)

LESSER MARSHWORT

Apium inundatum

Carrot Family [Apiaceae]