How to identify and forage Texas wild mustard: bastard cabbage

Latin name: Rapistrum rugosum
Common names: Bastard cabbage, turnipweed, turnip weed, giant mustard
Season: Spring and early summer
Edible: Yes, entire above-ground plant
Flavor: Good to great
Nutritional: Yes, vitamins K, A, C, E and all the Bs, also copper and iron

Identification difficulty: Novice

Rapistrum rugosum, most commonly know as bastard cabbage, and less commonly as giant mustard, turnipweed or turnip weed, seems to be nothing more than a tall, cheerful yellow wildflower that paints Texas in swaths of color. 

But looks can be deceiving. 

Bastard cabbage is a wild mustard, (cabbage is in the mustard family), that gets it's common name from its highly invasive nature. Originally from Southern Europe, the Mediterranean and Northern Africa, bastard cabbage has spread to 17 U.S. states and has hit Texas particularly hard. 

Bastard cabbage has a deep, deep taproot that makes it hard to "root" out, (ha, ha, ha), and a habit of being one of the first things to flower in the spring, getting well-established before native plants can get a foothold. Indeed, it's rapidly displacing native wild flowers, like bluebonnets.

It's also edible and quite tasty when prepared correctly. So let's take a moment to get to know this invasive weed, you you too can try it!

Bastard cabbage identification 

Special note: Bastard cabbage is relatively easy to identify once its flowering, but can be more challenging before that. I recommend not harvesting this plant before flowering unless you have become fairly familiar with it, or are familiar with foraging mustards in general. 

After construction of apartment complexes, there are often
fields of bastard cabbage, which spring up in disturbed soil.

Location and season

One reason why bastard cabbage is so invasive is because it's one of the earliest greens we will see pop up in the season, usually by the first week of March hear in Texas. It gets a head-start on many native plants. 

Trails are another common place to find bastard cabbage.
Note the height and size of the mature plants.

Additionally, this is a ruderal species. That means that it's one of the first plants to get established if the ground is disturbed. In purely natural areas, disturbed ground is most common around creeks and in flood plains. But humans frequently disturb the ground for construction, road work, creating trails and pathways, in fields for seasonal farming, and for many other reasons. These are all good places to look for bastard cabbage--though don't eat it from near a highway or any other potentially contaminated area. It can also grow in and around trees that would usually provide too much shade for other plants, as bastard cabbage gets established before the trees leaf out.  

Plant size and shape

Bastard cabbage begins as a basal rosette, or a circular mat of leaves coming out from a central point, flat against the ground. Very quickly those leaves start to build up, creating a "fluffy" circle. 

When mature, plants will reach around 3' at the very tips of their flower stalks. They will be quite leafy for about 2/3 of their height, then be almost bare branches with just tiny leaves and flowers. The diameter of the leafy base will be between 1' and 2 1/2'. 

4-petaled yellow flowers in oval-shaped clusters

Flowers and fruits

The flowers are the most distinctive part of bastard cabbage, and I recommend not foraging them until they flower, at least not until you are quite familiar with the plant. 

Flowers are around 1/3 to 1/2 inch, bright yellow, have 4 petals in a cross shape. They grow at the ends of the central stalk or the ends of side branches in oval-shaped clusters.

Flowers appear by mid-spring (late March/early April in Texas) and the plant will generally be done flowering by late spring (May here in Texas). 

The flowers leave behind small, teardrop-shaped fruits, the size of a pencil lead, which will cling to the stalk until they ripen in to seeds. 

Stalk and branches

The stalk for bastard cabbage is light green and looks like it has textural striations along it. There aren't any red spots, though right before the plant bolts, the junction between the baby branches and the main stalk might look a little reddish or orangish. 

Right before the plant bolts the main stalk will have a green flower bud, and the baby branches will also have tiny buds (see the area circled in red). The stalk will be about 1/4" in diameter at this point. 

The branches are never directly opposite each other, they are always slightly offset vertically. But they will always alternate which side of the stalk they come off of. 

When the plant bolts (begins its reproductive phase), the central stalk will shoot up about a foot taller than the leafy base. The green buds will turn into yellow flowers, and the baby branches will grow out, making the whole plant multi-branched. 

When mature, the stalk will thicken to 1/2" or 3/4" in diameter and become a brighter, almost lime green. The branches can be grow to be 1/2" thick. 

Incredible variation in mature leaf shape, size, number of lobes, lobe size, and edge texture. 

Leaves

Bastard cabbage has some frustratingly complicated leaves. At the base of the plant and in the basal rosette, leaves will be quite large, from 8" to 12" long. They are often dark green and very wrinkly, but can also be medium green and unwrinkled. They have a long central mid-rib that is light green or white. 

The mature leaves are always deeply lobed, but sometimes those lobes can be more or less even in size and there can be many of them (above right), other times they can appear more as a spoon shape--with one giant lobe at the end of a long leaf stalk, with only tiny, barely noticeable lobes running along the stalk (above left). 

Just like leaf shapes, leaf edges also vary greatly. Edges will be scalloped, small toothed, large toothed (like a saw blade), wavy or even nearly smooth, though never fully smooth. 

To make things even more complicated, many of the smaller leaves near the top of the plant will be triangular or lanceolate and may or may not have any lobes. 

This is why it's important to use more features than just leaf shape at first. 

Many, but not all, mature leaves will have textural bumps.

Bastard cabbage plants will always have several leaves that are covered in tiny, textural bumps. But not EVERY leaf will have this feature. They are more common on mature leaves, and may be significantly less obvious than on the example above. 

Bastard cabbage in the kitchen

Stalk at the perfect stage

Stalk and branches 

The tender, young stalk and branches are my favorite part of this plant, and it's only available for about a week or two every season. You want the central stalk before it bolts, while the flowers are still green buds. Even after the central stalk begins to flower, side branches that still have buds will still be good. 

Bend these tender areas until they break. The part that broke off easily is the tender part to cook and eat, but if it doesn't break easily and instead bends or cracks, the plant is too mature and will be woody. 

These should be prepared cooked. I generally do a strong blanch first before cooking them a second way, like stir-frying, oven roasting, grilling, adding to sauces or simply preparing them with a cheese sauce.

Bastard cabbage stalks taste nearly identical to broccoli rabe or broccolini, which they are related to.  

Leaves

When raw, bastard cabbage leaves taste TERRIBLE. They are hairy and have an unpleasantly papery-rough texture. But when you give them a quick blanch they become soft and incredibly mild in flavor--as well as very slightly sweet, like young corn. 

Once blanched or otherwise cooked, bastard cabbage leaves have the texture of spinach.  They are good throughout the entire season, from early spring to early summer. 

Flowers & fruits

Both flowers and the tiny fruit can and should be eaten raw, though I don't really bother with the fruit--unless I'm just stripping the stems and branches for the flowers and some of the fruit get mixed in. 

Roots

Although I don't know of any mustard that has poisonous roots, I also have no information of anyone having eaten bastard cabbage roots. They are most likely edible but I have not tried them and cannot vouch for them.

Seeds

Bastard cabbage seeds should be avoided. Not because they are poisonous, but because if you approach the plant while it is seeding, you might inadvertently get some seeds on your clothes, shoes or in your hair, and transport this highly invasive plant to new areas. Pets should also be kept out of bastard cabbage patches for the same reason. 

Nutrition

Given its status as a noxious weed, no studies have been done on the specific nutrition of bastard cabbage. But it is a member of the mustard family, and mustard greens are one of the most nutritious vegetables you can eat. 

According to Healthline, mustard greens as a group are extremely high in Vitamin K, which is essential for wound healing and bone strength; each serving has over your daily requirement. They also also rich in Vitamin C (supporting the immune system, helping your body make collagen, and facilitating iron absorption),  and have a significant amount of Vitamin A (supporting healthy tissues in your eyes, skin, bones and soft tissues), and Vitamin E (an anti-inflammatory that also helps shield your body from the UV rays of the sun). 

Mustard greens are also one of the highest plant sources of copper (essential to red blood cell production and nerve health), iron (also important for red blood cell health and energy) and ALL of the B vitamins. 

We don't really know exactly how bastard cabbage compares to cultivated mustards, but there is probably a pretty strong alignment. 

Bastard cabbage look-a-like species

In general, as long as you are harvesting bastard cabbage when it's flowering, and you look at the flowers carefully, you are unlikely to confuse it for anything else besides a different wild mustard. There are many other yellow-flowering wild mustards, but all are edible and hard to distinguish from one another. 

That said, if you harvest them before flowering, there are a couple species to look out for. 

Other wild mustards, members of the genus Brassica and cousins - Edible

Field mustard, Brassica rapa. Credit Wikimedia commons, 
no usage license required

As mentioned above, all wild mustards are edible, provided you can correctly identify them as mustards. One of these is Brassica rapa, or common field mustard, and it's found on every continent except Antarctica. This is the plant which many cultivated vegetables originate from, including nappa cabbage, turnips, bok choy and broccoli rabe (rapini). 

Other wild mustards that look like bastard cabbage include black mustard, Rhamphospermum nigrum. an invasive species in the US, named for it's black seeds (flowers are still yellow), yellow mustard, Sinapis alba, the seeds of which are used in the yellow mustard condiment, and more. But if you are in Texas, it is most likely bastard cabbage you will find. 

Ragworts and groundsels, members of the genera Jacobaea, Senecio and Packera - Dangerously poisonous

Young bastard cabbage leaves, left
Poisonous ragwort leaves, right

Ragwort flowers have more than 4 petals,
and they are not in a cross pattern. 

There are three genera that are commonly called ragworts, groundsels, butterweeds, and a few other common names: Jacobaea, Senecio and Packera. These are dangerously and insidiously poisonous plants as they don't kill you or even make you sick right away. But the toxins build up over time, especially with repeated consumption, slowly damaging your liver and kidneys. There is also evidence that they may cause cancer as well. 

There are hundreds of individual species of ragworts and not all resemble mustards--though some also resemble other edible wild plants. 

Ragwort leaves can resemble those of bastard cabbage, and the plant also forms basal rosettes. However, the flowers have many petals, not 4, and they are arranged in a circle, not a cross. 

Bastard cabbage as an invasive

Because bastard cabbage is a highly invasive species, you can't possibly over-pick it. But you CAN accidentally spread it, if you aren't careful. Here are some steps you can take to prevent that, while harvesting this plant for consumption:

• Avoid the plant late in the season (late spring/early summer) when the plant has gone to seed. Don't risk seeds getting on your clothing, hair or pets and possibly falling off to contaminate new places. 
• If you find small patches, pull the plant up by the root, rather than just picking above-ground parts. 
• When you dispose of plant parts make sure they are or will be DEAD--a black trash bag in the Texas sun is a good option. Burning is another one. Do not compost them, or boil them first before you compost. 
• Wash your car during frequently during the season, especially if you think seeds may have gotten on it in some way. 
• Plant native seeds where and when you can, especially on freshly-turned soil.