Tall, Yellow Brassicas
What are they?
This page covers members of the brassica family that typically grow more than 70cm in height and have yellow - usually (although not always) showy - flowers. Since the group includes a number of species that are not particularly closely related, they differ quite widely in their appearance, which should actually help with the identification process. They all share the family traits of four-petalled, yellow flowers that are followed by distinctive seed capsules. Some of these species will often grow rather shorter, so they are also included in the page on short, yellow brassicas and it is always worth checking both these pages when making an identification.
Where are they found?
This is a group of only loosely related plants, so there is much variation in the habitat choices - from arable farmland and grassland to waste ground and wetlands. However, the habitat can be a valuable aid to identification for some species, so be sure to check these details in the individual species notes below.
Identification
All these plants have yellow, four-petalled flowers, so you need to look elsewhere for identification clues. Start with noting shape of the leaves - both basal (if present) and stem leaves, especially noting whether they are simple or compound and whether the stem leaves have stalks or clasp the stem. With the flowers, it can be useful to check whether the sepals are carried close to the petals, or stick out noticeably. Finally, the shape of the seed capsules can be very useful and should be studied carefully; overall size and shape should be noted, as well as the size, shape and hairiness of the 'beak' - the usually elongated tip of the seed capsule that typically contains no seeds.
Common Winter-cress Barbarea vulgaris
A native biennial or short-lived perennial, found throughout East Anglia in all but the driest, sandy soils. Occurs in a variety of grassy and disturbed places, especially roadsides. Flowers April to July. Winter-cresses have rich yellow flowers and glossy green leaves, the latter first appearing over winter rather than in the spring. Basal leaves with broadly rounded leaflets; upper stems leaves more or less entire with toothed edges, not deeply lobed. Flower buds hairless.
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Early Winter-cress Barbarea verna
(American Winter-cress) Introduced from south-west Europe, despite the alternative English name! An uncommon to rare biennial or short-lived perennial, found scattered throughout the region in a few areas of rough ground and waste places. Long-known around the Felixstowe area especially. Flowers March to June. Winter-cresses have rich yellow flowers and glossy green leaves, the latter first appearing over winter rather than in the spring. Basal leaves with 4-10 pairs of small, rather angular leaflets; upper stems leaves deeply cut into finger-like lobes. Petals usually more than 5.6mm in length and at least some ripe seed capsules over 40mm long.
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Medium-flowered Winter-cress Barbarea intermedia
Introduced from mainland Europe. An uncommon to rare biennial or short-lived perennial, found scattered throughout the region in a few areas of rough ground and waste places. Flowers March to June. Winter-cresses have rich yellow flowers and glossy green leaves, the latter first appearing over winter rather than in the spring. Basal leaves with 2-6 pairs of small, rather angular leaflets; upper stems leaves deeply cut into finger-like lobes. Petals usually less than 5.6mm in length and ripe seed capsules less than 40mm long.
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Great Yellow-cress Rorippa amphibia
A native perennial of wet ground and water margins that is very much a feature of rivers, meres and pingos in Breckland, but occurs in small quantity elsewhere, too. Flowers June to August. A relatively tall species that may grow to over 100cm in height and often in extensive colonies. Leaves are highly variable, with basal leaves often deeply notched into finger-like lobes, while upper leaves are often simple with serrated edges.
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Creeping Yellow-cress Rorippa sylvestris
A native perennial of damp ground and also occasionally a weed in gardens and disturbed areas. Flowers June to August. A low-growing species that spreads and forms persistent mats of vegetation; flowering shoots can reach 60cm in height, but often much shorter. Lower leaves with toothed leaflets, upper leaves more or less reduced to a row of finger-like leaflets.
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Marsh Yellow-cress Rorippa palustris
A native annual or short-lived perennial of damp ground, found in small number along waterways and occasionally ponds or wet depressions, throughout the region. Flowers June to August. More or less intermediate between the previous two species; being relatively small (usually to about 60cm) but not mat-forming. Leaves very variable, from deeply lobed to more or less entire with serrated edges.
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Flixweed Descurainia sophia
An ancient introduction of disturbed ground on light, sandy soils, known from at least Roman times. Scarce except in Breckland and parts of the Suffolk Sandlings and North Norfolk coast, where it can be locally abundant on arable land. Flowers June to August. The tiny flowers with petals no bigger than the sepals are confusing as they don't immediately bring to mind a member of the cabbage family. However, the growth style and elongated seed pods are very much like other members of the family. Leaves are deeply dissected and delicately fern-like.
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Perennial Wall-rocket Diplotaxis tenuifolia
An ancient introduction, most often found in urban or suburban areas and locally common around Great Yarmouth, Lowestoft, Ipswich and Mildenhall, with scattered populations elsewhere. Flowers May to September. A winter-green perennial, with plants often growing to nearly a metre in height and forming rounded, bushy mounds. Compared with Annual Wall-rocket, leaves are more deeply cut, plants grow overall much larger and the stalks of the ripe seed pods are much longer.
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Annual Wall-rocket Diplotaxis muralis
Introduced from southern Europe and widespread, though generally most common on lighter, sandy soils. Most frequent as a garden annual weed and often found growing from wall bases and pavement cracks. Flowers May to September. A much smaller and less branched species that Perennial Wall-rocket. Compared with Perennial Wall-rocket, leaves are less deeply cut, plants are shorter (less than 50cm) and the stalks of the ripe seed pods are shorter.
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Wild Cabbage Brassica oleracea
Introduced and commonly grown as a vegetable in a variety of cultivated forms, from which occasional plants escape or survive for a short time on rough ground, field edges and similar places. Flowers April to June. A hugely variable plant due to the creation of a great number of forms and varieties, including Cabbage, Cauliflower, Brussels Sprouts, Kohl Rabi and Kale. Important identification features include an overall waxy bloom, a flower spike that elongates (open flowers do not overtop the unopened buds) and seed pods that are hairless, elongate and with a short, blunt beak. Plants can survive a number of years if left undistrubed and become quite woody at the base. Flowers have erect (not reflexed) sepals and pale yellow petals.
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Oil-seed Rape Brassica napus subsp. oleifera
Introduced and commonly grown as an arable crop, from where spilt grain during transporting can appear along roadsides, field edges and waste places. Since about the late 1970s, this has been by far the most likely yellow brassica to be found in much of the wider countryside, but this is not always reflected in the information given in books. Flowers April to July. A tall, glaucous, hairless plant with vivid yellow, large-petalled flowers. Upper leaves have rounded bases that clasp the stem; flower buds just overtop the open flowers. Seed capsules are long, large and stout, with a long beak.
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during harvest |
Turnip Brassica rapa
Introduced. Formerly widely grown as a root crop (subspecies rapa), but these days more likely to be found as an oil-seed form (confusingly, subspecies oleifera). Widespread, but considerably more scarce than Oil-seed Rape. Flowers April to July. A tall, glaucous, slightly bristly plant with vivid yellow, large-petalled flowers. Upper leaves have rounded bases that clasp the stem; flower buds do not overtop the open flowers. Seed capsules are long with a long beak, but not as stout as those of Oil-seed Rape.
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Mizuna Brassica rapa var. nipposinica
(Mibuna, Japanese Mustard) Introduced. A relatively new arrival, being grown as a salad crop or for use in stir-fry recipes. Included here as it is different enough in its appearance from other brassicas to cause confusion if found. It comes in a variety of forms but typically has the leaves deeply cut into finger-like lobes. Some varieties have purple leaves.
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Chinese Mustard Brassica juncea
Introduced. A rare casual where seed is spilt, but likely to become more common as it is now occasionally used in agricultural 'cover crops', when it is often referred to as Brown Mustard. Flowers May to August. A tall, green, slightly bristly plant with yellow flowers. Lower leaves coarsely and irregularly lobed, upper leaves variably toothed or entire, but not clasping stem at base. Flowers with sepals only partly reflexed (compare with Charlock, which is similar). Seed capsules are long with a long, slender, rounded, hairless beak. Beak typically no more than a quarter as long as main part of seed pod.
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Black Mustard Mutarda nigra
Native chiefly in wet areas, especially in the Fens and along coastal floodbanks and sea walls. Also occurs much less frequently elsewhere as an occasional stray from plants introduced as crops. Flowers May to August. A tall, robust, often much-branched plant which may reach 2-3m in height. Green, becoming slightly glaucous above, with coarsely bristly stems and leaves; flowers yellow and smaller than those of cultivated species. Lower leaves coarsely and irregularly lobed, upper leaves variably toothed or entire, but not clasping stem at base. Seed pods are shorter than most of the other Brassica species, somewhat 'knobbly' and held stiffly upright, close to the main stem.
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Charlock Rhamphospermum arvensis
An ancient introduction of all kinds of disturbed ground, especially arable farmland. Common and widespread, though generally absent from the more acidic, sandy soils. Flowers May to July. Usually less tall than the Brassica species and usually more obviously branching. A green, slightly bristly plant with yellow flowers and often a reddish tint to the stems. Lower leaves coarsely and irregularly lobed, upper leaves variably toothed or entire, but not clasping stem at base. Flowers with sepals clearly reflexed (compare with Chinese Mustard, which is similar). Seed pods are narrow with an elongated, slightly flattened beak, which may be hairless or slightly hairy. Beak typically at least a third as long as main part of seed pod and often much more.
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White Mustard Sinapis alba
An ancient introduction, formerly grown as a crop but much less so now, although currently being used as a component of agricultural cover crops or green manures, so may increase again in the wider countryside. Flowers May to August. A green, slightly bristly plant with yellow flowers. Lower leaves coarsely and irregularly lobed, the end lobe usually not much larger than the side lobes. Upper leaves stalked. Flowers with sepals clearly reflexed (compare with Chinese Mustard, which is similar). Seed pods are relatively short compared with other members of the group, but are noticeably hairy and have a rather extravagant, elongated, well flattened beak.
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Hoary Mustard Hirschfeldia incana
Introduced from southern Europe and known from one or two scattered locations for many years. More recently, has been appearing with greater frequency in suburban locations across the region, perhaps in response to environmental changes. Flowers May to September. Easily told from other members of the group by its obvious covering of stiff, white hairs, especially on the lower leaves and stem. Flowers a little smaller and paler than most other members of this group, with the flowering stem becoming much-branched when the side arms elongate as the seed pods develop. Seed pods are relatively short and held flattened to the stem, each pod having a short, irregularly swollen beak. Sometimes said to be similar to Black Mustard, but the whole plant is much hairier than that species, the leaves are smaller and more evenly lobed and the pods are distinctive with their knobbly beaks.
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Bastard Cabbage Rapistrum rugosum
Introduced from southern Europe and generally rare, but well established populations are known around Great Yarmouth, Ipswich and Eye and it can be common and sometimes locally dominant where it occurs. Flowers May to September. Plants become tall - to 100cm - and bushy, with very long, sinuous, flowering stems and often sprawl over. leaves and stems rather bristly. Seed capsules are distinctive, become globular with a spiked top (the remains of the style) and ribbed sides.
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Warty Cabbage Bunias orientalis
Introduced from eastern Europe/western Asia. Occasional plants appear here and there, perhaps from spilt bird seed or remnants of salda crops. More persistent colonies are known from Cambridgeshire and near Weston Longville, Norfolk. Flowers May to September. Rather similar to Bastard Cabbage but the seed capsules are unevenly oval in shape, tapered at the apex and with irregular, warty bumps.
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Wild Radish Raphanus raphanistrum subsp. raphanistrum
Probably an ancient introduction from Neolithic times and now a widespread and common plant throughout most of our region on a wide range of disturbed ground, field margins, waste places, tips and similar locations. Flowers May to September. Once known, this is an easy plant to recognise, with its coarse, bristly leaves and stems and its seed pods that have faint ribbing between the developing seeds. Plants are often relatively short, but usually have spreading branches, making them more noticeable and obvious than the species covered under the small, white brassicas. Flowers usually have dark veins and populations usually have a mix of both white and pale yellow flowered plants among them. The petals have long bases to them, forming a distinct cross shape.
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Sea Radish Raphanus raphanistrum subsp. maritimus
A native biennial or short-lived perennial which is locally common along the coast on muddy soils, especially in the Lowestoft and Great Yarmouth areas. Flowers June to August. Very similar to Wild Radish but, being longer-lived, it more often forms larger, many-branched clumps with more woody stems. Flowers usually bright yellow but rarely white. Seed pods on average are shorter than those of Wild Radish, with fewer seeds inside and are strongly constricted between each seed.
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Common Rocket Eruca vesicaria
(Garden Rocket) Introduced from SW Europe and grown as a salad green. Occasionally found where self-seeded on roadsides and rough ground where it has escaped from cultivation. Flowers May to November. Superficially similar to Wild Radish but differs in a number of ways. Flowers dull, yellowish-cream with darker veins, leaves hairless (providing the Rocket of salads) and seed capsules with a broad-based, flattened beak.
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Hedge Mustard Sisymbrium officinale
An ancient introduction, now firmly established and widespread as a common weed of all types of cultivated and waste places. Flowers May to July. An upright plant with, eventually, a much-branched flowering head. Plants start flowering when still small, single-stemmed and with a well-developed basal rosette of sharply compound leaves. As the plant develops, the basal leaves die off, but the plant continues to flower and forms side branches, each side branch progressively elongating as the seed pods ripen. Thus, this plant has many guises, but its tiny flowers and its pods pressed close to the stem make a distinctive combination.
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Tall Rocket Sisymbrium altissimum
Introduced from southern Europe and now well-established in the light, sandy soils of Breckland, mostly as an arable weed. Occasional elsewhere on similar, sandy soils. Flowers June to August. Growing to around 100cm in height, this is a distinctive plant with its compound leaves cut almost to the veins, pale yellow flowers and wiry, very long seed pods.
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Eastern Rocket Sisymbrium orientale
Introduced from southern Europe. Quite well established on rough ground and as a pavement in several of the larger towns and cities of the region. Flowers mostly April to June to but occasionally much later (even into autumn). Forms a distinctive tangle of open branches with much of the appearance due to the remarkably long seed capsules (5-12cm long). Basal leaves are pinnate, upper leaves typically with backward-pointing lobes that can give them an arrow-head appearance.
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Pale Rocket Sisymbrium irio
(London Rocket) Introduced from southern Europe. A very rare species with less than ten records from our region and no current populations known. Flowers June to August. An upright, sometimes branched species with pale yellow flowers, deeply lobed leaves and very long seed pods that usually overtop the open flowers.
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Wallflower Cabbage Coincya monensis ssp. cheiranthos
Introduced from southern Europe. A rare species in our region that ocasionally appears as a short-lived introduction. A small population has persisted for many years in East Suffolk and a new population was found in North Norfolk recently. Flowers May to September. A variable species with several subspecies, often upright to a metre in height but may be shorter and more sprawling. Flowers pale yellow, leaves distinctively deeply lobed.
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Woad Isatis tinctoria
Introduced from mainland Europe. Formerly grown for the blue dye that it produces but now grown as an occasional garden plant and only rarely found where self-seeded on rough ground. Flowers May to August. Leaves are unlobed and clasp the stem at the base. The seed capsules hang in rows and tremble in the wind.
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