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Portrait of Hogweed

Nature · Wildflowers & flowers

Hogweed

Native · flowers May–Aug · verges, hedgerows and rough grassland

Heracleum sphondylium — Apiaceae

Hogweed, or cow parsnip, is the robust native umbellifer of summer verges, with ridged hollow hairy stems, broad lobed leaves and big off-white umbels. It is not the dangerous giant hogweed, but its sap can still cause a skin reaction in sunlight. It follows cow parsley in the umbellifer calendar and is one of the great insect plants of midsummer.

How to spot them

  • ▸Ridged, hollow, hairy stems, usually about a metre and sometimes to 2 m, without purple blotches
  • ▸Broad, rough, hairy leaves divided into a few large lobed segments (unlike the fern-like leaves of cow parsley)
  • ▸Large flat umbels of off-white flowers, with the outer petals enlarged, May to August
  • ▸Hollow stems were used as pea-shooters by children
  • ▸DANGEROUS look-alike: giant hogweed (Heracleum mantegazzianum) is 1.5–5 m, with purple-blotched, bristly stems, huge deeply cut leaves and umbels up to 60 cm; its sap causes severe burns in sunlight
  • ▸DANGEROUS look-alike: hemlock (Conium maculatum) has hairless, purple-blotched stems, fine fern-like leaves, an unpleasant smell and is deadly poisonous

How to know it

Ridged, hollow, hairy stems, broad lobed leaves and big off-white umbels on a verge in midsummer; not the giant of the same genus

Hogweed — Heracleum sphondylium, the native one.

Children made pea-shooters, water guns and swords from its hollow stems

Hogweed.

Its sap can cause a skin reaction in sunlight, but far milder than that of the giant invader

Hogweed — reactions tend not to be as severe as with giant hogweed.

Folk names for this native umbellifer include cadweed, clogweed, eltrot, madnep and cow parsnip

Hogweed.

The native umbellifer with rounded, broad, hairy leaves and unblotched stems that reaches at most 2 m, against the 5 m giant with blotched, bristly ones

Hogweed versus giant hogweed.

Flowers from May to August, though it can flower all year, and is common on verges and rough grass

Hogweed.

Quick-fire facts

  • •Family Apiaceae; Heracleum is named for Hercules
  • •Wildlife Trusts: flowers May to August, though can flower all year round; hollow hairy stems, broad hairy divided leaves
  • •RHS: robust native biennial or short-lived perennial, generally about 1 m, sometimes 2 m; toxic to skin with sunlight, but reactions tend to be milder than giant hogweed
  • •Giant hogweed: non-native, from the Caucasus, first recorded in the wild in the UK in 1828 in Cambridgeshire; up to 5 m; sap causes phytophotodermatitis; it is illegal to plant it or let it spread
  • •Hemlock: native, up to 2 m, hairless purple-blotched stems, unpleasant smell, deadly poison; flowers June to July
  • •Cow parsley flowers first (April–June), then hemlock and giant hogweed (June–July), with common hogweed from May to August
  • •RHS gives folk names cadweed, clogweed, cow parsnip, eltrot, giant parsnip and madnep
  • •Widely visited by insects, including beetles and hoverflies, because of its open, flat umbels

Drill it — 7 cards

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