Robin Wall Kimmerer, self-described “mother, scientist, decorated professor and enrolled member of the Citizen Potawatomi Nation,” wrote the book on moss. In Gathering Moss: A Natural and Cultural History of Moss, she explains that mosses “are the most simple of plants, and in their simplicity, elegant.”  

She is right about simplicity and elegance, though I would add a component of complication to any description of mosses. While these organisms are a biologically-basic bryophyte, they have a two-part reproductive routine that makes for a convoluted coupling.

To begin, consider the bryophyte. Bryophytes are not exactly byzantine beings; they have no roots, stems, or flowers. Instead, they absorb nutrients through their plant surfaces. Lacking true roots, they tend to be small and can thrive on surfaces that rooted plants can’t, such as rocks and pavement. In addition to the mosses, this group includes liverworts and hornworts. 

Notwithstanding its form and ability to function, what is most intriguing are moss’s procreative peculiarities.  

Mosses can reproduce sexually and asexually. Asexually, reproduction occurs when a piece of the plant breaks off and grows into its own individual plant. Nothing too saucy. 

However, sexual reproduction involves an intimate and intricate dance of duality, called heteromorphic alternation of generations. This two-phased cycle includes structures called gametophytes and sporophytes that have one set of chromosomes (haploid) and two sets of chromosomes (diploid), respectively. Both structures have a role in the plant’s replication. 

As we must start somewhere, even in a circle, let’s begin with the familiar. 

The haploid gametophyte generation has a single set of chromosomes and is the recognizable form that we consider moss. Within the gametophyte, hidden inside of the leaf-like surface are two types of structures, the antheridia that carries the male cells and the archegonia that hold the female cells.  

It takes rain or at least some moisture to dislodge the sperm from the antheridia. The sperm moves with the moisture and is attracted to and falls into a nearby egg-containing archegonia to produce a diploid zygote. 

That fertilized zygote or embryo is encased and from the gametophyte a single stem-like projection grows. This projection, called a sporophyte, has a stem called a seta, and a capsule at its terminus. The sporophyte solves the problem of the mosses’ flower-less and seed-less existence. The capsule holds the diploid zygote that has undergone a few cell multiplications.

Moss contains many emerging sporophytes that appear as a forest of vertical growths. If you look now at mosses, you will see these setae, with their capsules at the end, hold their ready to fledge offspring. 

When the wind comes and the cap of the capsule opens, fertilized spores escape and are carried away to find a new spot to grow into another moss plant. The newly-settled moss spore will grow into a haploid gametophyte. And then the cycle continues anew. 

While this all sounds a bit confusing, the magic and mysteries of mosses are fascinating enough to fill a whole book — the one that we should all read to better understand and be inspired by the unique and important properties and poetry of moss. 

Suzan Bellincampi is Islands director for Felix Neck Wildlife Sanctuary in Edgartown and the Nantucket Wildlife Sanctuaries. She is also the author of Martha’s Vineyard: A Field Guide to Island Nature and The Nature of Martha’s Vineyard.