Another one of the crucifers that is easily confused with the ones I've posted about before. A very common agricultural plant that is now often found naturalised in roadsides, hedgerows and field edges, commonly cultivated for the oil from it's seeds it is actually an edible too.
this plant was found growing on a verge at the side of a wood, a tall plant nearly 3 feet tall and very attractive actually.
the leaves also clasp the stem as do those on brassica rapa, but notice the colouration of the rapeseed plant, how distinctively blue grey green it is, much more so than wild turnip, it almost has that mealy appearance.
also notice that generally (though not always, it depends on the subspecies) as a deciding factor in identification the flowers are higher than the buds, whereas in wild turnip it's the reverse.
Though I have often been told that all crucifers without exception are edible I find this difficult to believe as research into certain brassicas tends to say otherwise (with certain parts of the plant anyway) and the above plant is an example of this.
The seed contains a substance called Erucic
acid and there have been a number of reports of animals being poisoned after eating this plant. At one point in time oilseed rape contained 40% erucic acid and this would have had profound detrimental health impacts on those who consumed it, with modern intervention and genetic modification it now contains less than 2% erucic acid.
Although the glucosinolates in the seed (those substances that can have toxicological effects) have been reduced significantly the same can't always be said for the compounds in the foliage.
Though classed as edible, can you be sure that the plant you're eating is the correct cultivar? There are a tremendous amount of subspecies of this plant all with differing properties and all classed as edible, but do be wary, like many things in our wild larder any toxicity involved will tend to be cumulative, so eat sparingly and you shouldn't have a problem, the young leaves and the flower buds are the best, personally I give the seed a miss after all it is used for biodiesel and was once one of the finest machine oils available!