Heracleum maximum

Cow Parsnip

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Family: Apiaceae (Carrot / Parsley family)

Mid-Atlantic bloom time: May - July
Mid-Atlantic fruit ripe: July - August

CAUTION: Cow Parsnip's clear phototoxic sap is a skin irritant that may case a rash or burn after contact, especially when exposed to sunlight.

Cow Parsnip is a native biennial that can grow to impressive sizes, achieving a height of 3 meters and large leaves up to 60cm across. Its hollow stems are unsplotched, mostly green (can have some purple coloring, especially at nodes) with fine white hairs. Its white flowers form mostly flat umbels (the typical form of the parsley family) up to 30cm wide. The leaves are ternate and irregularly toothed, cleft, or serrate. Cow Parsnip's seeds are heart-shaped.

Distinguishing from Giant Hogweed: While Cow Parsnip is similar to the non-native noxious Giant Hogweed (Heracleum mantegazzianum) from the western Caucasus region of Eurasia, there are key differences. Giant Hogweed grows to twice the height and has deeply incised ternate leaves that can be up to 1.5 meter or larger across with many narrow and jagged lobes. It has purple splotches on its stem with coarse white hairs, especially at its nodes. Its flowering umbels are more rounded, like an umbrella, rather than flat, and they are twice the size of Cow Parsnip. Giant Hogweed's seeds are oval, not heart-shaped or as round as Cow Parsnip's. Moreover, Giant Hogweed's phototoxic sap can cause SEVERE rashes, burns, and blistering from even minor contact with the plant.

30 May 2012 Appalachian Trail in Shenandoah National Park (Central District), VA	30 May 2012 Appalachian Trail in Shenandoah National Park (Central District), VA	28 May 2021 Shenandoah National Park (Central District), VA	19 June 2021 Shenandoah National Park (Central District), VA
19 June 2021 Shenandoah National Park (Central District), VA	21 June 2014 Shenandoah National Park (Central District), VA	19 June 2021 Shenandoah National Park (Central District), VA	28 May 2021 Shenandoah National Park (Central District), VA (purple coloring (not splotched) at stem node)
26 July 2019 Shenandoah National Park (Central District), VA (developing seeds; note rounded heart shapes)

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