Boydston's spleenwort facts for kids

Asplenium × boydstoniae, also called Boydston's spleenwort, is a very rare fern. It is a hybrid fern, meaning it's a mix of two different fern types. It formed when Tutwiler's spleenwort (A. tutwilerae) and ebony spleenwort (A. platyneuron) crossed. Scientists first grew this hybrid in a lab in 1954 using special growing methods. It wasn't found in nature until 1971. Kerry S. Walter discovered it in Alabama, where Tutwiler's spleenwort naturally grows. Walter named it after Kathryn E. Boydston, who was an expert in growing ferns. This fern mostly looks like its ebony spleenwort parent, except for the very tip of its leaf.

What it Looks Like

Boydston's spleenwort is a small fern. It looks a lot like the ebony spleenwort. Its stem is a shiny dark brown. This dark color goes almost to the end of the leaf. The very tip of the leaf then turns green. Most of the leaf is divided into smaller parts called pinnae. The very end of the leaf is long and has rounded sections.

Its Leaves and Stems

The fronds, or leaves, of A. × boydstoniae can grow up to 21 to 30 centimeters (8 to 12 inches) long. They can be about 3.5 to 4.0 centimeters (1.4 to 1.6 inches) wide. The stipe is the stalk part of the leaf, below the main blade. It is about 0.5 to 1.5 centimeters (0.2 to 0.6 inches) long in medium-sized ferns. This stalk is a glossy dark brown.

The main part of the leaf, called the blade, is shaped like a spear. It is flat at the bottom. The blade is divided into many pinnae, usually 15 to 27 on each side. Larger ferns grown in labs can have 25 to 35 pinnae. The tip of the blade is long and pointed. The pinnae near the tip become smaller and join together. The dark, shiny color from the stipe continues up the main leaf stem, called the rachis. This dark color covers about seven-eighths of the frond's length. The pinnae do not have their own stalks; they are attached directly to the rachis. They can be triangular, spear-shaped, or slightly curved. Each pinna has a small ear-like part at its base, pointing towards the leaf tip.

This fern cannot make healthy spores. Its spores are found in small clusters called sori, which are up to 2 millimeters (0.08 inches) long. The fern itself is triploid, meaning it has three sets of chromosomes. It has 108 chromosomes in total.

How it's Different from Other Ferns

Boydston's spleenwort can sometimes be confused with other Asplenium hybrids or non-hybrid ferns. It looks most like the ebony spleenwort (A. platyneuron). You can tell them apart by the long, pointed tip of Boydston's spleenwort's leaf. Also, the last one-eighth of its rachis is green, not dark. If you look closely with a microscope, its spores are not fully formed.

It also looks similar to two other hybrid ferns: Graves' spleenwort (A. × gravesii) and Kentucky spleenwort (A. × kentuckiense). But in those ferns, the pinnae have short stalks, not attached directly. They also have fewer pinnae, usually 5 to 12, not 25 or more. Plus, the dark color on their stems and rachis only goes halfway up the frond. It's easy to tell it apart from Tutwiler's spleenwort (A. tutwilerae). Tutwiler's spleenwort has fewer pinnae, which are more pointed and uneven. It also has a longer stipe and a shorter leaf blade.

How it Got its Name

The first person to study this fern was Herb Wagner. In 1954, he created it in a lab. He did this by breeding the young forms (called gametophytes) of Tutwiler's spleenwort and ebony spleenwort. He thought it would be hard to find this fern in the wild. But in 1971, Kerry S. Walter found it in Hale County, Alabama.

Walter officially described the fern in 1982. He named it ×Asplenosorus boydstonae. He chose this name to honor Kathryn E. Boydston. She was an expert in growing spleenworts and other ferns in labs. Walter put it in the ×Asplenosorus group because one of its parent ferns, Tutwiler's spleenwort, came from the walking fern. Walking fern was sometimes placed in a different genus called Camptosorus.

The next year, in 1983, John W. Short changed the name. He didn't think Camptosorus should be a separate group. So, he moved the fern to the Asplenium genus. He also corrected the grammar of the name, making it Asplenium × boydstoniae. Later studies have shown that Camptosorus fits inside Asplenium. So, scientists today don't see Camptosorus as a separate genus.

Where it Lives

Asplenium × boydstoniae was first grown in a lab before it was ever found in nature. It might have been the first fern to be discovered this way. In the wild, it is only known from Havana Glen in Hale County, Alabama. The first ferns found there were growing on rocks covered in moss and flat lichen.

The rocks in this area are a type called conglomerate. This means they are made of silica pebbles stuck together in sandstone. This sandstone is part of the Pottsville Formation. It contains iron and small amounts of calcium. The soil in this area is slightly acidic, with a pH between 5 and 6.