Nomenclature

Species name:

Diplotaxis erucoides   (L.) DC.

Author(s):

Carl von Linné;
   Sweden, 1707-1778

Augustin Pyramus de Candolle;
   Switzerland, 1778-1841

Common names:

White Wall Rocket, White Rocket

Maltese name:

Ġargir Abjad

Plant Family:

Brassicaceae   (Mustard (Cress) Family)

Name Derivation:

Diplotaxis = ? unknown;
erucoides = looks like plants of the Genus Eruca (Latina)

Synonyms:

Crucifera erucoides, Euzomum erucoides, Sinapis erucoides

Remarks:

-

Morphology

Specifications & Description

Life Cycle:

Annual.

Growth Form:

THEROPHYTE (Annuals)

Habitat:

Fields, waysides, traffic islands, places with plenty of soil.

Frequency:

Very Common

Localities in Malta:

Very Common throughout the countryside of the Maltese Islands especially in uncropped fields. Often seen in traffic islands in October-November.

Plant Height:

20-60cm.

Flowering Period:

Sep - Jun

Protection in Malta:

Not Protected by Law (LN200/2011 or LN311/2006)

Red List 1989:

Not listed in the Flora section of the National Red Data Book (Lanfranco, 1989)

Poison:

Not Poisonous.

Herbaceous annual or biennial which is very common throughout the Maltese especially in Autumn/Winter. It consists of a green, erect stem with tiny white bristles, which forms many branches each giving rise to a terminal raceme of white flowers. The plant has a developepd taproot.

The basal and adult leaves are stalked and irregularly lobed. They have one or two pairs of basal leaf-lobes, cut deeply almost to the midrib, and a very large rounded terminal lobe. The shape of the young upper leaves is more or less maintained but they are usually sessile. Leaves have a crenated or shallow-dentate margin and prominent pinnate veins which normally have sparse tiny bristles.

The infloresences are racemes of many flowers of which 4 to 8 are found in blossom. The white flowers measure about 16-18mm across and consist of 4 narrow sepals, 4 white petals that slightly overlap each other and are arranged diagonally to each other (or cross-shaped), 6 stamens of which 4 are long and central, and 2 are short and lateral, and a central pistil with a superior ovary and swollen green stigma. The stamens produce yellow pollen.

When the flower expires, it drops its sepals, corolla and stamens leaving the ovary which elongates and forms a slender rod-shaped fruit called a siliqua. They are green (but can partially attain a purple-brown colour), have a body which is slightly bulging with the seeds inside, and an apical short beak. Mature pods measure between 25-38mm long and 2mm across and store around 40-80 seeds that are arranged in stacked pairs at each side of a central partition called replum. When mature, the fruit walls open with a sudden twist causing the seeds inside to scatter at a certain distance. The central translucent replum remains visible for some time. The seeds are ovoid (with a tiny indentation), yellow-brown, smooth, and about 1-2 mm accross.

Information and Details

Allergy to Diplotaxis erucoides pollen:

Abstract from research by P. Garcia Ortega et al [304] about Allergy to Diplotaxis erucoides pollen: occupational sensitization and cross-reactivity with other common pollens " Background: Diplotaxis erucoides is a common weed of the Brassicaceae family widespread in southern and central Europe.

Methods: A total of 410 consecutive patients referred for allergy study of rhinoconjunctivitis and/or asthma were skin tested with D. erucoides pollen, 14 proving positive. A purified D. erucoides pollen extract was prepared to perform quantitative skin tests, provocation tests, immuno-blotting, and EIA inhibition in the 14 sensitized patients.

Results: Three patients, directly involved in viniculture, had rhinoconjunctivitis related to D. erucoides pollen. No D. erucoides-related symptoms were observed in most patients, who were also sensitized to Artemisia pollen. RAST was positive in 12/14 patients and nasal provocation tests in 9/12. The molecular masses of the most prevalent IgE-binding proteins ranged from 26 to 27.5 and from 31 to 34 kDa. D. erucoides pollen inhibited the IgE-binding of other sensitizing pollens in the three viniculture workers, whereas both Artemisia and D. erucoides pollen produced similar heterologous inhibition in the pooled serum of the remaining, nonclinically affected, D. erucoides-sensitized patients.

Conclusions: D. erucoides pollen may be an important prevalent aeroallergen, particularly in rural areas. It may act as an occupational allergen in vineyard workers, in whom it seems to be the primary sensitizing agent, playing a secondary cross-reactive role in other sensitized patients. "

Go in the links section to read full text document about this research

The seed is best sown in situ as soon as it is ripe, though it can also be sown in situ in the spring [KF]. The seed usually germinates in the autumn and survives as an over-wintering rosette [17]

Leaves can be eaten raw or cooked. They possess a mustard-like flavour, they can be added to salads [217].

No evidence of medicinal use was found [SM]

Personal observations

Dispersion
Dispersion of seeds is by sudden outwards twisting of the 2 outer walls (valves) forming the siliqua [SM]

The plant is abundant in November and December in Malta, and is responsible for the formation of white carpets of flowers, usually over an uncropped field during the months of November and early December. During these months, there are not many flowers in bloom, and so this makes this species to predominate. [SM]



Not much information about this plant has been found, neither in books nor on the internet. If you can supply further information to be included in this profile, please, do not hesitate to email me. Full reference credits will be given.

Photo Gallery   (36 Images)

IMAGE: DTXER-01
Photo of a flower raceme and the pod-shaped purple-brown fruit.

IMAGE: DTXER-02
Close-up photo of an adult flower which consists of 4 white petals arranged as the shape of a cross. Very rarely, specimens with pale violet flowers are seen.

IMAGE: DTXER-03
Close-up photo of 2 flowers having 4 petals arranged in the shape of a cross.

IMAGE: DTXER-04
Photo of several flowers at the top of the flowering branch.

IMAGE: DTXER-05
Another photo of the flowers of thos species.

IMAGE: DTXER-06
Close up photo of lateral view of flower highlighting the pistil surrounded by the stamens having yellow anthers and lilac erect, firm filaments.

IMAGE: DTXER-07
Close-up photo of a flower showing the arrangement of the 6 stamens around a central pistil at the centre of the flower.

IMAGE: DTXER-08
Photo of an inflorescence made up of racemes of 3 - 8 white blossoming flowers. Each flowering branch can produce up to 80 flowers, but they do not blssom together, but gradually with time.

IMAGE: DTXER-09
Close up photo of a flower (lateral view) showing the 6 stamens and a central pistil with a swollen stigma. The colour of the stamens' filaments is green. Many flowers have purple or pale purple filaments.

IMAGE: DTXER-10
Photo of inflorescnce at the top of the flowering branch. It is a raceme which is clustered with white flowersat the top, and progressively gets more lax down the flowering stem, where the fruit is found.

IMAGE: DTXER-11
Close up image of few young flowers, composed of 4 petals, 6 stamens (4 central and long, 2 lateral and short) surrounding a central pistil with a swollen stigma.

IMAGE: DTXER-12
Photo of flowering branch with flowers and fruit-pods (known as siliqua).

IMAGE: DTXER-13
Scanned image of the flower against a dark background.

IMAGE: DTXER-14
Scanned and annotated image of 4 flowers showing in detail their various flowering parts.

IMAGE: DTXER-15
Scanned and annotated image of a longitudinally dissected flower (with some petals and sepals removed) showing the arrangement of the 6 stamens (2 short and lateral and the other 4 are longer and central) around the pistil.

IMAGE: DTXER-16
Photo of leaf of Diplotaxis erucoides which have 2-4 pairs of lateral lobes and a terminal lobe, the latter being always the largest lobe of the leaf.

IMAGE: DTXER-17
Scanned and annotated image of young and adult leaves. They are deeply lobed with the apex lobe being the largest.

IMAGE: DTXER-18
Scanned image of an adult leaf. It has deep lobes at the base followed by an apical and terminal roundish large lobe. The margin is shallow dentate (or crenate) and has pinnate branching.

IMAGE: DTXER-19
Top view photo of a plant. It is a herbaceous, branched plant with several flowering stems bearing clusters of numerous white flowers.

IMAGE: DTXER-20
Photo of plant.

IMAGE: DTXER-21
Photo of young plant in leaves and developing buds.

IMAGE: DTXER-22
Photo of the upper plant of the plant which consists of numerous, spreading-out siliqua and racemes of white flowers.

IMAGE: DTXER-23
Scanned image of the upper part of the plant including a cauline leaf, several fruit pods and a raceme of white flowers at the apex.

IMAGE: DTXER-24
Scanned and annotated image of the flowering stem showing racemes of flowers at the upper part followed by plenty of long, spread-out, seed-bearing siliqua.

IMAGE: DTXER-25
Close up photo of the siliqua which is elongated and often reddish brown in colour. The beak (tip) is very short.

IMAGE: DTXER-26
Scanned image of fruit-pods (siliqua) at different maturity stages. The pods tend to be purple brown especially if they are exposed to the sun.

IMAGE: DTXER-27
Magnified scanned image of 3 fruit-pods. They have a long pedicel, a short beak and slightly bulging bodies with the seeds inside.

IMAGE: DTXER-28
Scanned image of ripe siliqua and their seeds. The walls break open at the base and twist rapidly to disperse seeds some distance away.

IMAGE: DTXER-29
Magnified scanned image of 3 open ripe pods. They have this characteristic translucent central partition to which seeds are attached to in pairs at each side. Each pod holds between 40 - 80 seeds each.

IMAGE: DTXER-30
Scanned image of the seeds. They are roughly ovoid in shape with a small indentation, 1mm in length and light brown in colour.

IMAGE: DTXER-31
Scanned image of subterranean parts which consist of a developed tap-root and numerous outgrowing roots.

IMAGE: DTXER-32
Photo of plants with empty siliqua. The remaining translucent septum of the siliqua glistens bright against sunlight.

IMAGE: DTXER-33
Photo of a several plants in their natural habitat, that is, rich soils such as fallow fields, disturbed soily areas and even in traffic islands and uncared gardens.

IMAGE: DTXER-34
Photo of an fallow field covered with white flowers of D. eurocoides (30/Oct/2005).

IMAGE: DTXER-35
Photo of an uncropped field covered with white D. erucoides and yellow Brassica rapa spp silvestris.Photo taken in a field near Dingli Cliffs during November 2004.

IMAGE: DTXER-36
Photo of an uncropped field covered with D. erucoides (white) and Brassica rapa spp sylvestris (yellow). Photo taken in fields near Buskett in December 2002. It is quite common to find populations of these two species together in November/December.

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