LESSER SWINE-CRESS

Lepidium didymum

(Formerly: Coronopus didymus)
Cabbage Family [Brassicaceae]

month8may month8jun month8june month8jul month8july month8aug month8sep month8sept

status
statusZneophyte
 
flower
flower8white
 
morph
morph8actino
 
petals
petalsZ4
tiny
type
typeZclustered
 
stem
stem8round
 
smell
smell8cress
cress

6th Sept 2015, arable fields, Maghull, Lancs Photo: © RWD
Like Pineapple Weed it seems to like driveways and perhaps even benefits from being driven over occasionally. Often prostrate and sprawling but otherwise up to 40cm high.


6th Sept 2015, arable fields, Maghull, Lancs Photo: © RWD
Spreads as a very low-growing mat.


6th June 2015, farmyard, Aughton, Ormskirk, Lancs. Photo: © RWD
With flowering tips and fruits spreading out along the sides like a test-tube bottle-brush.


23rd Aug 2015, East Lancs Road, Walkden, Gtr M/cr. Photo: © RWD
A pale-green plant with small creamy-green flowering clusters.


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
Pinnate leaves have 3 opposite pinnae plus a terminal one. The longer this white stems have shed the tiny seed pods from the numerous short side-stalks.


23rd Aug 2015, East Lancs Road, Walkden, Gtr M/cr. Photo: © RWD
A well-branched plant. Hydathodes at tips of leaves shed excess water. The partly flattened double-barrelled items are ripening fruits.


6th June 2015, farmyard, Aughton, Ormskirk, Lancs. Photo: © RWD
Tiny flowers about 2mm across at the growing tips of stems. Two stamens (sometimes 4 but not in these photos), one central stigma.


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
As-yet un-opened flowers snuggled between the reticulated developing fruits. Two under-developed paler fruits are amongst the un-opened flowers.


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Opened flower have 4 sepals, two anthers, and a double-barrelled developing fruit with single discoidal stigma atop (topmost flower). Tucked underneath opened flowers are some yet to open (just right of centre). Fruits on long(ish) stalks (bottom).


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Another view of same flowers as above.


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
A single flower with developing double-fruit in centre. Four mud-guard-shaped sepals cup the whole. Four triangular and paler petals poke out between the 4 sepals. The petals are shorter than the sepals. Two anther-tipped stamens (there can sometimes be 4 fertile stamens) are either side of the developing double-fruit. [On Swine Cress there are six fertile stamens].


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Atop the double-fruit is a reticulated but transparent discoidal stigma. Anthers bear cream-coloured pollen on each side of fruit.


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Pollen sprinkles the top of discoidal stigma like gold-dust, pollinating it.


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Two anthers with cream-coloured pollen either side of the developing fruit (central large body).


23rd Aug 2015, East Lancs Rd, Walkden, Gtr M/cr. Photo: © RWD
Developing double-seed-pods on lower half of flowering stem, flowers still opening at summit. Un-like the very similar (but larger) Swine Cress (Lepidium coronopus) the fruit are ovaloid and nicked (as opposed to having a short beak as for Swine Cress) and are on pedicles (stalks) which are longer than the fruit (as opposed to shorter for Swine Cress). (Doubled fruits not dissimilar to those of some Bedstraws such as Hedge Bedstraw (Galium album) but are flatter and probably smaller too).


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
Centre left is a ripe fruits ripe on the end of a longer stalk and ready to drop off as two separate seed pods, leaving the narrower remnant as a short white extension to the pedicle (stalk) - as on the pedicals just below that one.


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
Individual seed pods ripened to a flatter 'disc' with reticulated surfaces and very narrow rim.


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
Pinnate leaves, sometimes the pinnae themselves are forked (see photo A below). The plant is hairy, or not, this specimen being hairy.


4th Aug 2014, Hall Road, Sefton Coast. Photo: © RWD
Photo A. Leaf pinnae sometimes forked.


Easily mistaken for : the related but slightly larger Swine Cress (Lepidium coronopus) - see captions for differentiation between the two.

When crushed it smells strongly and similar to Garden Cress. It is a non-native introduced plant which has become naturalised. It likes to grow on arable fields and disturbed waste ground, often to be found near the sea or in the parks around London.


  Lepidium didymum  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae

 BSBI maps
genus8Lepidium
Lepidium
(Pepperworts)

LESSER SWINE-CRESS

Lepidium didymum

(Formerly: Coronopus didymus)
Cabbage Family [Brassicaceae]