BASTARD CABBAGE

Rapistrum rugosum

(Formerly: Rapistrum hispanicum)
Cabbage Family [Brassicaceae]

month8jun month8june month8jul month8july month8aug

status
statusZneophyte
flower
flower8yellow
morph
morph8actino
petals
petalsZ4
stem
stem8round
stem
stem8ribbed
sex
sexZbisexual

18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
A naturalised Neophyte; here occupying a street corner in protest. Most of our plants are the sub-species ssp. linaeanum. At up to 1m high it gets as high as does the similar Charlock


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The flowers are in a spherical cluster at the summit of long branches. The leaves seem to be all shapes (some near the base lobed) and sizes, many near ground-level but up to halfway up.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
Below the flowers the branched stems look bare, but...


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The stems are actually covered in the seed pods in various stages of ripeness which grow parallel to the flowering stems. The main branches below these stems them are devoid of flowers/pods.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The pods on these stems are very narrow, but elsewhere they are wider.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The petals are 4 per flower and yellow. The flowers appear not to have a sepals; the reader can see the long narrow part of each petal all the way down to the flower stalk (petiole). But the 4 narrow sepals are splayed out.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
A typical flowerhead, unopened flower buds pale green at the top awaiting their turn to open when ripe. The older flower get dragged down the stem as the stem grows 'ever' longer between each flower.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The flowers have 6 anthers in a 4 square + 2 outliers arrangement. In the centre a style with a discoidal pale-green stigma just a tidge lower than the anthers.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
Bottom centreis an as-yet unopened flower with the 4 yellow petals wrapped around the style. Just beyong the petals are the 4 pale-green narrow sepals before they splay out. In the unopened flowers above the pale green sepals surround the pale-green as-yet undeveloped petals.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The anthers are bent over at the top of each filament.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The developing seed pods have three sections to them: the lowest section where they join onto the flower stem (pedicel). A bulging section next followed by a longer and narrowest section at the top which is still tipped by the stigma.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
A better view of the above description.


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
The seed pods are actually quite variable in shape on Bastard Cabbage. Here is a riper one with a more spherical but slightly ribbed bulge containing the seeds topped by the old style and stigma. Beneath the pod itself is a cylindrical part wrapped by two purple objects. Tgey all sit upon a whitish disc before joining the ex flower-pedicel. [Two withered (failed to be fertilised?) 'pods' higher up the stem.]


18th June 2019, a street, Waterloo, Sefton Coast. Photo: © RWD
Only a very few of the low leaves are lobed, the lobes having indecisive teeth. (On the otherwise very similar but much less frequently found Steppe Cabbage any lobed leaves have very distinct teeth. The other notable difference is in the seeds pods, which consist of two prolate stacked spheroids, the lower smaller, the upper larger and with a slight taper at the end).


14th April 2011, Lynn Common, IOW. Photo: (CC by 2.0) Geoff Toone
The topmost opened flower shows two of the 4 narrow (here pale-green) sepals splayed out


14th April 2011, Lynn Common, IOW. Photo: (CC by 2.0) Geoff Toone
A much neater flower showing the 4 petals tapering drasically but almost parallel to the 6 anthers and central style. (But the 4 narrow sepals still cannot be espied; maybe they readily drop off?)


Some similarities to : Steppe Cabbage (Rapistrum perenne) which is in the same genus, but this has pods which consist of two oval bulges, the furthest being the larger which contains the seed and tapers to a tip.

No relation to : Bastard Agrimony (remonia agrimonioides), Bastard Balm (Melittis melissophyllum), Bastard Toadflax (Thesium humifusum) [plants with similar names belonging to differing families].

The seed pods are very distinctive, having three areas of differing diameter and length and are mostly the only reliable way to identify this plants, but they are quite variable. They are 3 to 12mm long, with the style being the longer section which is between 1 to 3.5mm long (0.8mm to 5mm in extreme cases). The bulging central area is ribbed and has reticulate lines, hairy or not and contains just one seed (sometimes no seed).


  Rapistrum rugosum  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae
 BSBI maps
genus8Rapistrum
Rapistrum
(Cabbages)

BASTARD CABBAGE

Rapistrum rugosum

(Formerly: Rapistrum hispanicum)
Cabbage Family [Brassicaceae]