Sword fern is the most abundant fern in and around Nanaimo. It grows as an understory plant in our coniferous forests, interspersed with dull Oregon grape (Berberis nervosa) and salal (Gaultheria shallon).
Sword fern is an evergreen, its leathery dark fronds are present in the winter too. This photo was taken in December. Photo credit: Richard Droker via FlickrEarlier in the season, the fronds (leaves) of sword fern are lighter-coloured and upright. Photo credit: Willamette Biology via FlickrNew leaves emanate at the center of the plant from a compact, hidden stem. Note the darker green colour of the older leaves. Salal (Gaultheria shallon), dull Oregon grape (Berberis nervosa) and starflower (Lysimachia trientalis) are visible in the photo too. Photo credit: Douglas FraserIf you peer down the center of a sword fern plant, you’ll see the new leaves, tightly rolled up, covered in scales, and hiding the growing tip of the stem. Photo credit: James Gaither via FlickrUnderside of a sword fern leaf. Note the rusty-coloured scales on the leaf stalk. The dots are sori, clusters of tiny spore-bearing structures. This leaf was photographed early in the season, before the spores mature. Later, the sori take on a rusty-orange colour. Photo credit: Douglas FraserAs the sporangia grow, the umbrella-like ‘indusium’ that covered them begins to disintegrate. You can discern spores as white rice-like grains inside the individual sporangia. When the spores are mature, the sporangia break open. The backbone-like structure on the sporangium acts like a loaded spring that violently turn the ruptured sporangium inside out, flinging the spores into the environment. Photo credit: Richard Droker via FlickrSometimes people get sword fern and licorice fern (Polypodium glycyrrhiza) mixed up. A closer look at the leaves should clear up any confusion. On sword fern (left) the individual leaflets are attached to the stalk through a narrow attachment point, and the leaf stalk has rusty-coloured scales. On licorice fern (right) the leaflets are attached to the stalk by a broad base, and the leaf stalk is smooth – no scales or flakes. Photo credit: Lynda Stevens
