posted 3 weeks ago
Wild parsnip is easy to distinguish, especially when young—the young leaves have a coat of fine hair over them. Hemlock is a completely (or nearly) hairless plant, and I almost never run into it. On most parsnip plants, they are only once compound, i.e. the larger oval leaflets all emerge from the same long rachis (stem). Parsnip, unlike the others, has yellow flowers that bloom in summer (not spring—golden alexanders bloom in spring, are much lower, and have foliage similar to ground elder).
Wild carrot, at least here, tends to be very hairy, covered all over with stiff hairs. They have a delicious, carroty-anisey smell. Both wild carrots and cow-parsley have multiple-compound leaves, but on cow parsley there are fine hairs covering the leafstalks, and the leaves (i.e. fronds) are more triangular in outline compared with carrot and parsnip.
Cow parsley is the most hemlock-looking of the three but has triangular rather than rounded leafstalks, is finely hairy (velvety), and doesn’t have any white bloom. There are other characteristics too but these are good to get you to the “I think I know!” stage.
Ground elder is wildly invasive along riversides, and they also grow in variegated form next to buildings. They form a carpet of green and have a celery-parsley-ish scent. They are hairless, and have leaf stems triangular in cross section. The leaves are twice compound (splits into three, then each division is either lobed or divided into 2 or 3 parts). They are larger and more erect than golden alexanders, and bloom in summer rather than spring. The flowers are white and there are a number of ridges running up the flowerstalks. There are no large taproots, and are rhizome-forming (and quite aggressive).
I hope this helps! If you have any others you want to ask about I can try to answer.
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