Tree with Two Flowers

A group of blooming trees caught my eye near the local high school so I stopped to examine them. I really should get a bumper sticker that says “This car pulls over for strange plants and native flowers.” The plant turned out to be groundsel bush, Baccharis halimifolia.

What was particularly striking was that what appeared to be two different plants was actually the same species with male and female flowers on different plants (so, yes, technically they were two different plants). Baccharis is dioecious — male and female flowers are on separate plants.

Now we know plenty of dioecious plants (you do, really). Holly (Ilex) is one of the most common ones, but you need a hand lens to tell the difference between the male and female flowers on that one. Another example is fringetree (Chionanthus virginicus); that one is slightly more obvious if someone has already told you that the flowers are a bit showier on the male plant. Even then I think I’d need to see them side by side to recognize what “a bit showier” means.

Here is a whole page full of them: familiar names like juniper, persimmon, and willow are there. Dioecious plants are frustrating to gardeners that want fruit (like persimmon and hollies) but a blessing to those that don’t want it as well (think Gingko, a non-native tree with stinky female fruits).

Groundsel bush is considered a large shrub or small tree, growing up to 12 feet. As with many native plants, it has a delightful collection of common names: groundseltree, eastern Baccharis, sea-myrtle, consumptionweed, salt marsh-elder, and salt bush. The seeds on the female tree are very striking in the fall. I found one source that described them as “silvery, plume-like achenes” that resemble “silvery paintbrushes.” Here are some good pictures of the plant.

Mostly considered a plant of the coastal plain, apparently it is making its way more northward in the last few hundred years. Of interest is the fact that it is the only native species of the Asteraceae family that reaches tree size in the eastern US.

Groundsel bush is tolerant of saltwater spray so it is suitable for planting in beach communities or areas with brackish waters. In inland areas it is found in wet areas as well as disturbed places. Who knows how it got to this particular roadside near the high school? The plants are overhanging the sidewalk considerably so I expect a city crew will whack it back … and it will grow again next year.

I enjoyed discovering this new plant and learning more about it.