Spike moss

The genus Selaginella is the sole member of family Selaginellaceae. There are roughly 750 species in the genus, and they are commonly called spike mosses. They are vascular plants closely related to ferns. To say more about their phylogeny would take a book and invite controversy as there are several taxonomic classification schemes for Selaginella. I just think they are cool plants and want to shed a little light on the genus. That is a little oxymoron, as most Selaginella species prefer the darker places of the earth’s forests. Selaginella can be found on every continent except Antarctica.

The common name spike moss is a reference to the spore-bearing leaves on Selaginella which are grouped together in spikes or strobili. Selaginella are heterosporous, meaning that there are two kinds of spores. Megaspores are larger than microspores, and the larger become the female gametophytes while the smaller microspores become the male gametophytes. Reproduction can also happen vegetatively through several methods including stem cuttings and division of mature plants, and in horticulture, these methods of propagation are most common.

Several Selaginella species are hardy perennials in USDA Zone 7 and higher. Selaginella krausiana and its cultivars are useful landscape plants and work great as terrarium plants indoors. S. krausiana ‘Brownii’ is particularly beautiful. It reminds me of a brain sitting on the soil, or brain coral from my diving days. Another favorite is S. tamariscina, or white-tipped spike moss, which is native to most of Asia including Japan, Taiwan, and the Philippines.

Recently on a tour of the Amazon Spheres in Seattle, I was reacquainted with S. picta, a beautifully variegated species from southeast Asia. It is still somewhat rare in cultivation, though apparently fairly easy to grow in high humidity conditions like a terrarium. I can just imagine a beautiful terrarium with S. picta alongside a Begonia ferox that I wrote about a few months ago. Terrarium cultivation is a rapidly growing style of indoor gardening and we in commercial horticulture should consider seizing the opportunity to provide plants to support the trend.

The buzz about Selaginella

“The diversity of Selaginellas, coupled with the textures, colors, and size range make it a workhorse in both garden and home. It’s also a huge plus that some cultivars are hardy to USDA Zone 6, making them useful landscape plants in northern climates. New cultivars being introduced are going to make it even more valuable.”