Clubmosses

There are still a few green plants left in our November landscape, and some hold secrets you might not expect. Take this Interrupted Clubmoss (Spinulum annotinum), for example.

 Despite their name, Clubmosses aren’t mosses at all. They’re vascular plants, which means that – unlike mosses – they have true roots, stems, and leaves, along with internal plumbing (xylem and phloem) to transport water and nutrients. Clubmosses’ lineage goes back even further that the Horsetails we looked at last week, placing them among the oldest groups of plants on Earth. Collectively, Clubmosses are also called Lycopods.

Lycopods first appeared more than 400 million years ago but diversified and became more abundant about 350 million years ago in the hot, swampy, and oxygen-rich Carboniferous Period. Those ancient relatives of today’s Clubmosses grew to heights of up to 50 metres (165 feet) and formed vast, dense forests. Today, their legacy persists in three ways: as fossils (including those found here on PEI); as a major component of coal; and as modern, living Clubmosses.

That ancient lineage is impressive but is not the only unusual thing about Clubmosses. Like Ferns and Horsetails, Clubmosses reproduce by spores rather than seeds. But, unlike those other plants, Clubmoss spores are flammable!

Clubmosses’ tiny spores – each roughly 30 micrometres (0.03 millimetres, 1/1000 of an inch) in dimeter – have an oil-rich coating. That oil, coupled with the spores’ small size and high-surface-area-to-volume ratio, is the perfect recipe for creating a fiery flash when the spores are mixed with air and exposed to heat or flame. Sold commercially as Lycopodium powder, Clubmoss spores are used to create large, though short-lived, flashes for stage, screen, and magic shows, and they were used as flash powder in the early days of photography.

Because of their evergreen nature, Clubmosses are also sometimes collected for seasonal decorations. That’s fine in moderation, but these plants are very slow-growing and so are sensitive to overharvest. Interrupted Clubmoss is a great example, because each year’s growth is marked by a section of smaller leaves on the stem (shown by the arrows). In this case, that tiny section of plant took three years to grow; a long, trailing segment could easily be decades old.

Interrupted Clubmoss is among the most common of our dozen different species of modern Lycopods, and an interesting member of PEI Untamed!