Argyrochosma delicatula facts for kids

Argyrochosma delicatula is a special type of fern. It is mostly found in northeastern Mexico. You might also find it in one spot in Arizona. This fern likes to grow on rocks. It can be in sunny or shady places. A cool thing about it is the pale yellow powder under its leaves. This powder helps tell it apart from similar ferns. Scientists first described this fern in 1939. Later, in 1987, they moved it to a new group called Argyrochosma. These ferns are sometimes called "false cloak ferns."

What Does This Fern Look Like?

Argyrochosma delicatula is a medium-sized fern. It often grows on rocks. The fern has a compact rhizome, which is like its underground stem. This stem can grow sideways or stand upright. It has thin, orange-brown to dark brown scales. These scales are about 4 to 6 millimeters long.

The fern's leaves, called fronds, grow in bunches. A frond can be 10 to 25 centimeters long. Some are as short as 6 cm or as long as 35 cm. Nearly half of the frond's length is its stalk, called the stipe. This stalk is shiny and round. It has no hairs and is chestnut-brown to dark purple.

The leaf blades are shaped like triangles. They are deeply cut into smaller parts. The main stem of the leaf, called the rachis, is round and dark. Each leaf has 4 to 8 pairs of triangular sections. These sections are divided into even smaller parts. These tiny parts can be diamond-shaped, fan-shaped, or circular. They are usually 1 to 2 millimeters wide.

The underside of the leaf has a pale yellow powder. This powder is called farina. You might see a little bit of this powder on the top surface too. The leaves feel leafy, not tough or leathery.

The fern's spores are found in groups called sori. These sori are along the veins on the underside of the leaf. Each sporangium (spore case) holds 64 spores. These ferns have 54 chromosomes.

This fern looks a lot like Argyrochosma incana. But you can tell them apart. A. delicatula has yellow powder, not white. Its stems are brown to purple, not black. Its leaf parts are narrower. Also, A. delicatula has some powder on the top of its leaves.

How Scientists Name and Group This Fern

Scientists first described this fern in 1939. William Ralph Maxon and Charles Alfred Weatherby named it Notholaena delicatula. They found it in Coahuila, Mexico. The name "delicatula" means "delicate texture." This refers to how fine its leaves feel.

In the 1940s, other scientists thought this group of ferns might be a separate genus. In 1987, Michael D. Windham confirmed this. He created the genus Argyrochosma. He then moved this fern to that new group, calling it A. delicatula.

Later, in 2018, Maarten J. M. Christenhusz moved it again. He placed it in the genus Hemionitis, calling it H. delicatula. This was part of a plan to group similar ferns together.

Even though some have wondered if A. delicatula is truly different from A. incana, studies show they are separate. They are in the same family of ferns. This family also includes A. pallens, A. peninsularis, A. palmeri, and A. pilifera. All these ferns have pale powder. This powder is made of special compounds called terpenoids.

Where Does This Fern Grow?

Argyrochosma delicatula is mainly found in Mexico. It grows in the states of Chihuahua, Coahuila, and Nuevo Leon. One fern found in southeastern Arizona in 1880 was also identified as this species.

This fern likes rocky places. It can grow in sun or shade. It especially likes limestone ledges and shady slopes.