UNITED STATES—Ferns are foliar perennials. They provide neither floral color nor fragrance. They provide neither fruits nor vegetables. With few exceptions, they provide no shade. The very few that are deciduous are not impressively colorful for autumn here. Ferns cannot grow as hedges. Nor can they become lawns. They exclusively provide distinctive fern foliage.

They do so splendidly! Most produce the sort of distinctively lacy fern foliage that ferns are famous for. Some exhibit even more finely textured and airy foliage. A few exhibit a relatively coarse foliar texture. Almost all ferns are rich and deep green. Some are lighter or slightly yellowish green. A rare few are silvery gray, or display an intricate silver lining.

Almost all ferns that are popular within home gardens are evergreen. Most benefit from occasional grooming to remove deteriorating old foliage. Some produce new growth on top as old growth lies down below. Several grow most lushly after removal of all foliage prior to their growing season. A few deciduous types of fern defoliate for their dormancy.

Ferns are an odd bunch.

Ferns do not develop stems or trunks like most other vegetation does. They sprawl over the ground with rhizomes, which are fleshy stems. Rhizomes grow only in length, but not in diameter. Tree ferns grow upward as their rhizomes deteriorate below. Roots that grow through the deteriorating rhizomes form what seems to be trunks. Fern roots are fibrous.

Leaves of ferns are fronds. Such fronds of most ferns divide into pinnae, which are like smaller leaflets. Pinnae of some ferns divide into even smaller pinnae. Rachi are central stalks that suspend the pinnae within individual fronds. Ferns reproduce by spores, so lack flowers. Most ferns propagate efficiently by division of preferably dormant rhizomes.

Because of their fibrous root systems, ferns are complaisant to confinement within pots. Most ferns are naturally understory vegetation, so are innately tolerant of partial shade. Ferns that tolerate aridity as well as shade and confinement are delightful houseplants. Most ferns are very tolerant of relocation, although some must replace foliage to adapt.

Highlight: Sword Fern

It seems to be related to Boston fern because it is. Sword fern, Nephrolepis cordifolia, is a less refined species of the same genus. It does not want to live as a docile houseplant. Instead, it prefers room to grow and spread in the garden. It has potential to spread a bit vigorously though. Containment protects adjacent smaller perennials or bedding plants.

Sword fern foliage is the same light and slightly yellowish green as that of Boston fern. It generally stands more upright though. Rather than hang softly from planters, like Boston fern does, it leans outwardly. Its pinnately compound fronds can grow almost two and a half feet tall. Pinnae might be about an inch and a half long, with a slightly grainy texture.

Sword fern is not particularly discriminating about exposure, moisture or soil. It can cling to trunks of Canary Island date palms and infest their canopies epiphytically. Sword fern is greenest with regular irrigation and shelter from harsh exposure though. Its evergreen foliage can discolor and partially defoliate when distressed. Grooming might be tedious. Healthy colonies may hide their old foliage.

Tony Tomeo can be contacted at tonytomeo.com.