MARSH YELLOW-CRESS

Rorippa palustris

Cabbage Family [Brassicaceae]

month8jun month8june month8jul month8july month8aug month8sep month8sept

status
statusZnative
flower
flower8yellow
inner
inner8green
morph
morph8actino
petals
petalsZ4
stem
stem8round
stem
stem8ribbed
sex
sexZbisexual

14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
A glabrous annual which reaches 60cm in length and is less sprawling than Creeping Yellow-Cress. It differs from the similar Northern Yellow-cress in several features which will be illuminated on each appropriate photo.


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
It is similar to Northern Yellow-cress but that grows to just 30cm (60cm for Marsh Yellow-cress)


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
Flowers in tight bunches at the end of the side branches and at the summit of the main stem.


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
Most of the flowers have turned to fruit here.


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
The sepals on Marsh Yellow-cress are greater than 1.6mm long (whereas those on Northern Yellow-cress are less than 1.6mm long)


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
The ripe seed pods of Marsh Yellow-cress are 5 to 10mm long and many are slightly curved upwards (slightly longer at 6 to 12mm long on Northern Yellow-cress but again that is not a lot of difference).


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
But the stalks of the fruit of Marsh yellow-cress are 5 to 10mm long and only 1 to 2 times longer than the fruit and sprout from all around the stem (whereas the fruit of Northern Yellow-cress - being 6 to 12mm long, are also 2 to 3 times longer than the stalks and sprouting more on one side of the stem than the other side).

Your Author thinks that since these fruit are less than twice as long as their stalks and sprout from all around the stem they are thus those of Marsh Yellow-cress.

As an aside, it seems the fruit are encased in two opposite oblong-shaped 'boats' (as may also be the case for other species of Yellow-cress?)



14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD


14th June 2017, gutter, Woodhill Rd, The Burrs, Bury, Lancs. Photo: © RWD
It also differs from the similar Northern Yellow-cress in that that has only 2 to 5 pairs of lobes on the stem leaves (a slightly higher 2 to 6 pairs on Marsh Yellow-cress but that is not much difference at all!)


Not to be semantically confused with : Winter-cresses such as Winter-cress (Barbarea stricta) [a plant with similar name and with yellow flowers, but the leaves are much larger and the jizz also differs]

Some similarities to : Water-cresses such as Water-cress (Rorippa nasturtium-aquaticum) (but they have white flowers) and to other species of Yellow-cress (which have yellow flowers).

The books say that this plant grows in bare mud by freshwater, such as a lake, pond margin or reservoir and especially in ponds which drying out in summer. And pn railway tracks and other dry bare ground. But the population above are growing in the guttering of the road, albeit one which rarely gets driven near by vehicles because of several jutting out bits of pavement which are meant to slow down the speed of traffic. It indubitably becomes wet there during and after rain, but there is not much soil at all, but enough for other plants to also grow, such as grass.

The very similar Northern Yellow-cress Rorippa islandica often grows near the sea and seems to be far less frequent than is Marsh Yellow-cress. For differences, see photo captions.


  Rorippa palustris  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae
 BSBI maps
genus8Rorippa
Rorippa
(Yellow-Cresses)

MARSH YELLOW-CRESS

Rorippa palustris

Cabbage Family [Brassicaceae]