Heracleum lanatum - Cow parsnip

Apiaceae



I do not consider this plant a weed.  It is actually a native to the Pacific Northwest, and from what I have seen, it only occurs along roadsides and drainage ditches.  I've never seen this plant grow as a competitive weed in nursery crops.  However, because some of its close relatives are weeds, and because some may consider it a weed of fencerows, I include it on this page for thoroughness.

Heracleum lanatum - Cow parsnip

Cow parsnip is a biennial that spreads by seed.  Its habit is tall and spreading, growing up to 5 feet tall and wide.

Heracleum lanatum - Cow parsnip

Leaves are enormous, up to 16 inches long and 12 inches wide.  Each leaf is made up of 3 leaflets, with the terminal leaflet generally larger than the basal 2.  Leaf margins are serrated and lobed.

Heracleum lanatum - Cow parsnip

Stems are slightly ridged and hirsute (very hairy).  This is in stark contrast to the smooth and glaucous stems of poison hemlock.

Heracleum lanatum - Cow parsnip

Large swollen regions of the stem are conspicuous, and are really just flower buds waiting to emerge.  These swellings can be as large as an orange.

Heracleum lanatum - Cow parsnip

Flowers occur in a flattened compound umbel, typical of plants in the carrot family.  

Heracleum lanatum - Cow parsnip

The image above is of one umbel (which is a flower cluster itself).  Individual flowers are white with 5 petals.

Heracleum lanatum - Cow parsnip


MORE PHOTOS!

I take far more pictures than what normally makes it on the website.  To see the overflow section for cow parsnip, click here.



Return to the Weed Species Page

Return to the Weed Management Homepage



Email comments to James Altland