What is an umbellifer? What is the difference between cow parsley and hemlock? Is giant hogweed dangerous? Find out the answers to all these questions and more with our guide to umbellifers, including how to identify cow parsley, hogweed, giant hogweed, wild carrot, ground elder and hemlock.

By Kevin Parr

Published: Thursday, 16 March 2023 at 12:00 am

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Delicate clusters of flowers are dotting our verges and field margins; tiny petals balanced on short stalks and neatly splayed as though arranged by a florist. They are Apiaceae or Umbelliferae, commonly known as umbellifers, comprising more than 3,800 species worldwide and one of the earliest identified plant families.

The flower umbels that make the plants so distinctive can vary in colour from pink to yellow but are most often white. While some species, such as fennel or carrot, are familiar as food when cultivated, others can be deadly poisonous or cause allergic reactions. So it is probably safer to look but not touch.

In this guide, we explore six of the UK’s most common umbellifers, including cow parsley, hogweed, giant hogweed, wild carrot, ground elder and hemlock.

Interested in learning more about Britain’s flora? Check out our guides to orchids, bluebells and ferns.

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Common umbellifers of the UK

Cow parsley (Anthriscus sylvestris)

May might be most often associated with the rich white cascades of hawthorn blossom, but it is also a month when the verges begin to glow. Cow parsley (Anthriscus sylvestris) seems to line every rural road, thick enough in places to appear like a blanket of snow.

The flowers themselves are small and delicate, with five creamy-white petals on short stalks (known as pedicels) that are arranged in groups of up to 10 to form an umbel.

The leaves are green and feathery, almost fern-like in appearance. The stalk is striated, the vertical ridges becoming more distinct as the plant withers and dries.

Cow parsley is edible but it can be difficult to identify from some very poisonous relations.

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Hogweed (Heracleum sphondylium)

No sooner has the cow parsley vanished from our hedgerows and verges, than a similar, though larger, relative will often appear in its place. Hogweed (Heracleum sphondylium) is one of several umbellifers that appear through the summer months, although its size alone sets it apart from most.

It grows tall, as high as two metres, and the stems are similar in appearance to cow parsley, but thicker and more robust, with coarse and conspicuous hairs.

The umbels consist of more rays than cow parsley, as many as 45, while the white flowers sometimes carry a slightly pinkish tinge and can vary in size across the same plant.

The fresh ‘spears’ of young hogweed are popular with foragers and said to have a similar taste to asparagus or broccoli. As with all umbellifers, you should be 100% sure of your identification before touching the plant.

Orchids of the UK

Learn how to identify the UK’s most common orchids with our species guide.

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Giant hogweed (Heracleum mantegazzianum)

Introduced to the British Isles as an ornamental plant in the 19th century, giant hogweed (Heracleum mantegazzianum) has built itself a fearsome reputation.

It can grow to enormous size, often in excess of two metres and possibly as tall as five metres, with thick stems more than 8cm in diameter. The leaves hang heavy like tired hands, deep green with pronounced lobes and jagged edges.

The stalk is hollow and deeply ridged, predominantly green but with reddish-purple splotches and stiff, white, pronounced hairs.

The umbels are vast, measuring up to 60cm across and made up of between 50 and 150 individual rays.

Giant hogweed is fond of damp habitats and is often found beside water courses.

The sap of giant hogweed contains furocoumarin, which, even after minimal contact, can cause the skin to react strongly to sunlight, forming large, painful blisters. Contact with giant hogweed should be avoided, particularly under strong sunlight.

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Wild carrot (Daucus carota)

Wild carrot (Daucus carota) is widespread throughout the British Isles with the exception of the far north.

It does not grow particularly tall, rarely exceeding 60cm in height, and is typical of umbellifers with the exception of the three forked bracts (small, leaflike structures) that form beneath the flowerhead.

The leaves are slender but more robust than might be typical of cultivated species.

The umbel of the wild carrot is perhaps the most striking feature. Above the unique, pinnate bracts is found a splay of stiff rays that form a tight, almost semi-spherical, cluster of flowers. The petals are a crisp white, with the exception, often, of the central flower. This is deep red in colour.

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Ground elder (Aegopodium podagraria)

Although not native to the British Isles, having probably been introduced by the Romans, ground elder (Aegopodium podagraria) has certainly made itself at home. It is so called due to the shape of its leaves, which are triangular, toothed and ternate (arranged in threes), and the delicate white flowers that combine to resemble the elder tree (Sambucus nigra).

Although the two are not related, both are traditionally foraged. While the flowers and berries are the primary attraction of the elder tree, it is the leaves of ground elder that are sought. When young, they may be eaten as salad leaves, boiled, or used in soups.

The dark green leaves of ground elder first appear as shoots in late winter and early spring, making them conspicuous in shady corners. The flowers do not appear until May to July, at a similar time to the elder tree.

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Hemlock (Conium maculatum)

Any would-be foragers pondering the culinary value of umbellifers need not look beyond hemlock (Conium maculatum) as a potentially deadly example of misidentification. All parts of the plant contain coniine, as little as 150mg of which, when ingested, can be fatal to humans.

Hemlock has a foul odour, particularly when the leaves are crushed. What is sensible is to trust your senses. Hemlock is a poisonous plant that smells as though it should be left alone. And this is just as well, for in appearance, hemlock could very easily be mistaken for wild carrot and cow parsley and is often found in similar areas.

Hemlock leaves have a slightly glossy sheen, and its stem has distinctive purple blotches, and while cow parsley flowers earlier, there is an overlap in early summer.

If there is any doubt, then look but definitely do not touch.

Guide to British butterflies

In our expert guide, we take a look at butterfly identification, common butterfly species, how long butterflies live, and where to see them in the UK.

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