Dodders and roses - August 4, 2014

When one hears the word “parasite” most people think about worms, bacteria, or fungi. However, there are parasites in the plant kingdom as well. Dodders are parasitic vine-like plants that infest other plants as their hosts. In this case it is Common dodder (probably Cuscuta gronovii) on the salt marsh elder, Iva frutescens. While inhabiting mostly freshwater wetlands, common dodder can also sometimes make its way to the high salt marsh. After the dodder attaches to the host plant, it inserts a kind of false roots right into the host plant tissues and continues to feed off it. Dodder has no roots and no leaves (only small scales), and obviously, no chlorophyll either, hence the orange yellowing color. 

 

But, even dodders are not immune to insects. This dodder plant had a gall produced likely by dodder gall weevil (Smicronyx sculpticollis).This beetles spends almost their entire lives inside the protective walls of the gall, a kind of insect made habitat induced by the weevil larvae.

A much more showy (and tastier) plant makes its appearance on the salt marshes known this time of the year. Rose or marsh mallow (Hibiscus moscheutos) is one of the 3 species of marsh mallows found on New York salt marshes. As the name hints, the roots of the European species (Althaea officinalis) were used to make marshmallows in the past. Marsh mallows are also known for their medicinal properties.

Rose mallows have their share of specialized insects which are adapted to feeding off these plants. Hibiscus seed beetles (Althaeus hibisci) uses chemical cues from open petals to locate freshly open flowers. The beetles eat pollen and lay their eggs on the seeds. The beetles larvae are protected inside the see capsule, and have plenty of highly nutritious food for development. Thus, The entire life cycle of the beetles revolves around the lifecycle of the plant.