Heracleum lanatum - Cow parsnip
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.
Cow parsnip is a biennial that spreads by seed. Its habit is tall
and spreading, growing up to 5 feet tall and wide.
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.
Stems are slightly ridged and hirsute (very hairy). This is in stark
contrast to the smooth and glaucous stems of poison hemlock.
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
Flowers occur in a flattened compound umbel, typical of plants in the
The image above is of one umbel (which is a flower cluster itself). Individual
flowers are white with 5 petals.
I take far more pictures than what normally makes it on the website. To
see the overflow section for cow parsnip, click here.
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