Heracleum sphondylium L. ssp. montanum Briq.

Cow Parsnip

Heracleum sphondylium plant

Family - Apiaceae

Stem - Erect, stout, ridged, to 2 m, sparsely to densely pubescent with spreading hairs.

Heracleum_sphondylium_stemStem and leaf sheath.

Leaf - Alternate and usually basal, petiolate. Petioles densely pubescent, with base sheathing and strongly inflated. Blades broadly ovate to circular in outline, lobed or ternately compound, pubescent, toothed on margins.

Heracleum_sphondylium_leafBasal leaf.

Heracleum_sphondylium_leaf2Leaf and sheath.

Inflorescence - Terminal and axillary compound umbels. Involucre of 5-10 bracts to 2 cm long, hairy, deciduous. Rays numerous, 5-10 cm long, unequal in length, hairy. Involucel of 4-10 bractlets, hairy.

Heracleum_sphondylium_inflorescenceInflorescence.

Heracleum_sphondylium_involucelInvolucels.

Heracleum_sphondylium_umbelletUmbellet.

Florets - Numerous in each umbellet, on stalks to 12 mm long. Petals obovate, white, sometimes larger near edge of umbellet. Ovaries hairy.

Heracleum_sphondylium_floretsFlorets.

Fruits - To 12 mm long, oblong-obovate, flattened, sparsely hairy, tan with darker oil tubes between ribs.

Heracleum_sphondylium_fruitsFruits.

Flowering - May - July.

Habitat - Bottomland forests, ravines.

Origin - Uncertain.

Other info. - Authors such as Steyermark have treated American plants as a distinct species, Heracleum maximum, but differentiation from the Eurasion Heracleum sphondylium is uncertain. Under favorable conditions these plants can become coarsely gigantic, making the term "cow parsnip" seem somehow appropriate. Contact plants should be avoided, since the plants contain furanocoumarins which render them phototoxic. Exposure to the sap and then sunlight can cause potentially serious rashes and blistering.
Plants in this genus are rare in Missouri but relatively common in states to our west.

Photographs taken at Shaw Nature Reserve, Franklin County, MO, 5-25-2014 and 6-20-2014 (SRTurner).



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