The other day in my Facebook news feed there was a question about whether a plant someone had growing in their landscape was non-native Goutweed (Aegopodium podagraria) or native Golden Alexander (Zizia aurea). That got me thinking — besides the color of the blossoms, what is the difference.
To make it confusing, their blossom times overlap; Goutweed May-June and Golden Alexander May-July. But their flat-topped umbellar blossoms are different colors. The Goutweed has a white blossom, while the Golden Alexander has a golden yellow blossom. Also, the individual flowers are quite different (besides the color). The tiny yellow flowers of the Golden Alexander have five petals that fold inward and five yellow stamens, while the Goutweed’s tiny white flowers have five petals with five white stamens and a striking set of two long, white styles projecting from the top. There is also one subtle difference. The Golden Alexander has stalkless flowers in the center of an umblet, while the Goutweed has all stalked flowers.
Ah ha! This is even more confusing, but there are certain subtle differences which can be seen if one looks closely. The Goutweed leaves are twice compound, long stalked with up to nine leaflets, while the Golden Alexander’s are two or three times compound in groups of three leaflets. Also, the Golden Alexander leaves are more deeply serrated than the Goutweed’s and they taper to a narrow base, unlike the Goutweed. And of course the varigated species (Aegopodium podagraria ‘Variegatum’) is a dead giveaway for Goutweed.
When we moved to our current residence, the varigated variety of Goutweed was growing in a small garden in the pool area. It didn’t take long for it to revert to its green state and then move into the nearby woodland garden I created. It forms dense monocultures and crowds out other plants. Round-Up only burns the leaves and they regrow quickly. Digging it out is impossible because each little root fragment resprouts. Some have tried smothering, but that seems to be only a temporary setback. I’m continuing to experiment with herbicides and to remove the seedheads. I’ll keep you posted.
Yep, I can see why people are confused about which plant is which. The seed in the seedheads of both plants are quite fine, so that doesn’t help either. If not in bloom, the first thing I would consider is whether the plant appears as a colony or a monoculture. Then I’d examine the leaves closely. Once you get to know the individual plants, it will be easier for you to tell the difference in the leaves especially.
See also Invasive Goutweed (Aegopodium podgraria).