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Giant Hogweed Identification

Characteristics of the Giant Hogweed Plant:

  1. White flowers with 50-150 flower rays clustered into an umbrella shaped flower cluster up to 2.5 feet across
    giant hogweed umbrella shaped flower clusterGiant hogweed umbrella shaped flower cluster
  2. Between 7 and 14 feet tall (depending upon growth stage and if mowed or cut)
    Giant hogweed plants standing approximately 10 feet tallGiant hogweed plant standing approximately 14 feet tallMowed giant hogweed flower head - standing about 3 feet tall
  3. Huge leaves, incised and deeply lobed up to 5 feet across
    giant hogweed leaf - approximately 5 feet wide
  4. Stems are green with extensive purple splotches and prominent coarse white hairs. Stems are also hollow, ridged, 2-4 inches in diameter, and have a thick circle of hairs at base of leaf stalk
    giant hogweed stem having course hairs and purple blotchesGiant hogweed stem with course white hairs and purple blotches
  5. Seeds are dry, flattened, and oval. Approximately 3/8 inch long and tan with brown lines (oil tubes) extending 3/4 of the seed length that widen at ends
    Giant hogweed seeds - approximately 3/8 inch long with brown lines (oil tubes) extending 3/4 of the seed length
  6. Many plants are often misidentified as giant hogweed - the most common plant being cow parsnip. Please thoroughly look through the charts below to see the major differences between giant hogweed and cow parsnip, angelica, wild parsnip, and poison hemlock.
Giant Hogweed vs Cow Parsnip
Giant Hogweed Cow Parsnip
Leaf giant hogweed leaf is up to 5 feet wide.
Compound, lobed, deeply incised, up to 5 feet wide
cow parsnip leaf, compound, less incised than hogweed, between 2 to 2.5 feet wide
Compound, less incised than hogweed, between 2 to 2.5 feet wide
Flower giant hogweed, white umbrella-shaped flower clusters up to 2.5 feet wide
White umbrella-shaped flower clusters up to 2.5 feet wide
Cow parsnip white flat-topped flower clusters no larger than 1 foot wide
White flat-topped flower clusters no larger than 1 foot wide
Stem Giant hogweed stem - green with purple splotches and coars white hairs, 2-4 inches in diameterGiant hogweed stem - green with purple splotches and coarse white hairs, 2-4 inches in diameter
Green with purple splotches and coarse white hairs -
thick circle of hairs at base of leaf stalk, 2-4 inches in diameter
cow parsnip stem - green and ridged with fine white hairs, 1-2 inches in diameter
Green and ridged with fine white hairs, 1-2 inches in diameter
Flower Rays Giant hogweed flower rays with 50 or more rays per umbel
50 or more rays per flower cluster
Cow parsnip rays with 15 to 30 rays per flower cluster
15 to 30 rays per flower cluster
Seed Cow parsnip and giant hogweed seeds - cow parsnip seeds are heart shaped and giant hogweed seeds are oval shaped
Oval-shaped with oil tubes that extend 3/4 the length of the seed and widen at ends Heart-shaped with oil tubes that extend 1/2 the length of the seed
Flowering late June to mid July late May to late June
Common Giant Hogweed Lookalikes
Plant Name Height Stem Leaf Flower Flowering
Wild Parsnip wild parsnip plants can reach up to 5 feet tall
Up to 5 feet
wild parsnip yellow-ish green stem with full length grooves (no hairs or bristles)
Yellowish-green with full length grooves (no hairs or bristles)
wild parsnip leaf - compound, pinnate, 5 to 15 toothed leaflets, variably lobed, yellowish-green
Compound, pinnate, 5 to 15 toothed leaflets, variably lobed, yellowish-green
wild parsnip flower head with flat-topped umbel of flower clusters
Single flower stalk with flat-topped umbel of yellow flower clusters
late May - early July
Angelica Angelica stalk - 4 to 9 feet tall
4 to 9 feet
angelica stem - smooth, waxy purple, 1 to 2.5 inches in diameter
Smooth, waxy purple, 1 to 2.5 inches in diameter (no hairs or bristles)
angelica leaves - compound leaves that may extend up to 2 feet wide
Compound leaves that may extend up to 2 feet wide
angelica softball-sized and shaped clusters, greenish-white or white
Softball-sized and shaped clusters, greenish-white or white
mid May - mid June
Poison Hemlock Poison hemlock stalk - 4 to 9 feet tall
4 to 9 feet
Poison hemlock stem - smooth and waxy stem with purple blotches, 1 to 2 inches in diameter
Smooth and waxy stem with purple blotches, 1 to 2 inches in diameter (no hairs or bristles)
Poison hemlock leaf - bright green, small and fern-like, may appear glossy
Bright green, small and fern-like, may appear glossy
Poison hemlock flowers - small and white arranged in numerous flat-topped clusters on all branches
Small and white arranged in numerous flat-topped clusters on all branches
late May - late June