Eastern baccharis (Baccharis halimifolia), also known as groundsel bush or sea myrtle, is a perennial deciduous shrub associated with the high marsh system, often confused with marsh elder (Iva frutescens), due to their similar growth form and placement in the landscape.
One way to tell the plants apart is their leaves. Eastern baccharis has alternate, simple, thick egg-shaped leaves (up to 2.5” long), that are coarsely toothed above the middle of the leaf, although the uppermost leaves can have smooth margins. Marsh elder, on the other hand, has oppositely arranged, lance-shaped leaves toothed more regularly along their entire margin.
Eastern baccharis (Baccharis halimifolia) leaves.
Marsh elder (Iva frutescens) leaves.
This time of year, eastern baccharis is producing stalked clusters of small white flowers that form showy white terminal inflorescences. The salt marsh behind Nauset Beach in Orleans is practically ringed by an uninterrupted string of eastern baccharis shrubs, producing a picturesque border of small white fluffy flowers. These flowers produce abundant nectar that attracts various butterflies, including the monarch butterfly. In addition to food, these dense shrubs also provide cover for wildlife; during extreme high tides, both small mammals and birds have been reported to use emergent vegetation as island of refuge, and baccharis would serve this purpose well.