Structure of the Boston Fern

Fern Characteristics

• Ferns are different from the seed-bearing plants that are the predominant forms of plant life today. They don't have seeds but instead produce spores on the undersides of their leaves. They don't have flowers. Ferns have two distinct phases in their life cycle, the spore-producing stage, or sporophyte, which is the conspicuous stage grown as a houseplant or landscaping plant. The second stage is small, about the size of a child's fingernail, and needs water to complete. It is called the gametophyte stage. These tiny plants grow from the germinating spores, and they produce the male and female gametes, which unite and grow into the sporophyte generation again. Like seed-bearing plants, fern sporophytes have a vascular system. This is a system of interconnected tubelike cells that extend from the roots into all aboveground parts of the plant, forming a sort of plant plumbing system. The vascular system carries water, minerals and plant nutrients throughout the plant.

Fronds

• Boston fern leaves are called fronds. The leaf stalk that rises from the bottom of the plant is called a stipe, and the broad leafy part of the frond is called the blade. In Boston fern, the blade is divided into many small leaflets called pinnae, each attached to the central stem, termed the rachis, which goes down the middle of the blade. In more feathery varieties of Boston fern, the leaflets are in turn divided, and in other varieties these secondary divisions are divided yet again. The original variety of Boston fern has fronds 3 to 5 feet long and 2 to 6 inches wide.

Rhizomes

• Fern rhizomes are comparable to the stems of seed-bearing plants. In Boston fern, the rhizomes are mostly underground, and they give rise to the fronds that grow upward and the roots that grow sideways and down into the soil. Roots are fibrous and anchor the plant. They collect water and minerals, and transport them to the rhizome's vascular tissue. The rhizome also contains strengthening tissues that give rigidity and erectness to the plant. Boston fern rhizomes send out leafless stems called runners, which sprout roots wherever they touch the soil and produce a new plantlet at the end of the runner, which will also root. You can separate these from the mother plant when they get big enough.

Spores

• In the summertime, spores begin development in two rows of little rounded, raised bumps along the margins of the pinnae on the underside of a fertile frond. Each bump contains little spore-producing capsules called sporangia. The bump is called a sorus; plural, sori. As the sori mature, a protective kidney-shaped flap covers the sorus. The flap is named the indusium. When the spores are mature, the sorus releases them as a fine powder that gets blown on the wind. Some people collect the spores and grow them into the tiny gametophytes, but the gametophytes won't give rise to the same sporophyte cultivar as the parent fern. To propagate Boston ferns true to type, you need to root the runners or divide the parent plant.