|Common cow-parsnip, Heracleum maximum, aka H. lanatum.|
The genus name Heracleum (from "Hercules") refers to the very large size of all parts of these plants. (Wikipedia)
|The flower umbels are usually flat-topped, the leaves large and divided into 3 toothy segments.|
I have some difficulty distinguishing the smaller members of the carrot family, such as Queen Anne's lace, Angelica, etc., all with similar flowers and small leaves, but usually growing in different environments. Cow-parsnip is like them, but the leaves are large to huge, coarse, with a swollen base to the stalk. The plant can be anywhere from 1 to 3 metres tall, taller where the ground is damper. It grows on stream banks, in wet ditches, water meadows. And alongside roads in this damp climate.
To the casual observer, many members of the parsley family (Apiaceae) look similar. Many have white umbels of flowers and dissected leaves. Close inspection, however, shows noticeable differences in leaf shape (amount of dissection), flower (umbel) size, and habitat preferences. When identifying species in this family, habitat should be the first separator (wet or dry sites). In southwestern BC, cow parsnip is most easily confused with smaller plants of giant hogweed (Heracleum mantegazzianum), but may be separated from that species by its generally smaller size, leaf shape (it sports 3 distinct leaflets), and fruit shape. It may also be mistaken for poison hemlock (Conium maculatum). However, poison hemlock is generally much smaller than giant hogweed, with fern-like leaves and smaller flower umbels. Cow parsnip may also be mistaken for other wet-loving members of the Apiaceae, so care should be taken in the identification. (E-Flora BC)
The young stems are edible: coastal peoples peeled them and ate them raw or boiled. It was important to peel them; the leaves and the outer peel of the stems contain furanocoumarins, which can cause skin irritation and blisters on sunny days. (It needs the combination: exposure to the poison, plus ultraviolet light.)
|Flower head, from above, with assorted flies.|
Either there are no furanocoumarins on the flowers, or the flies aren't bothered by them.