Lobed spleenwort facts for kids
Quick facts for kids Lobed spleenwort |
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| Lobed spleenwort growing in a crack in schist rock | |
| Conservation status | |
| Scientific classification | |
| Genus: |
Asplenium
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| Species: |
pinnatifidum
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| Synonyms | |
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Asplenium rhizophyllum var. pinnatifidum Muhl. nom. nud. |
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The Lobed spleenwort, also known as Asplenium pinnatifidum, is a small fern. You can mostly find it in the Appalachian Mountains and the Shawnee Hills. It likes to grow in rock cracks where the soil is a bit acidic.
Scientists believe this fern came from a mix of two other ferns: the walking fern (Asplenium rhizophyllum) and the mountain spleenwort (Asplenium montanum). This mixing created a new fern with double the usual number of chromosomes, making it fertile. This process is called alloploidy. Even though scientists haven't found the exact first hybrid fern, the Lobed spleenwort looks like a mix of its two "parent" ferns. Its leaves are long and pointy like the walking fern, but they are also lobed (have rounded sections) like the mountain spleenwort.
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What it Looks Like
The Lobed spleenwort is a small fern with bright green, crinkly, and lobed leaves, called fronds. These fronds stay green all year round and grow in clumps. You can spot it by its shiny stem, which is dark only at the bottom, and its long, tapering, lobed leaves. Both the fertile (spore-producing) and sterile leaves look the same.
The fern's roots don't spread out much. Instead, its leaves grow close together from a single underground stem called a rhizome. This rhizome often branches out. It's about 1 millimeter (0.04 inches) thick and covered with dark reddish-brown or blackish scales. The stem (called the stipe) is shiny and dark reddish-brown at the bottom. This color fades to green towards the top. The stipe can be 1 to 10 centimeters (0.4 to 4 inches) long.
The leaf blade is usually narrow and triangular, or shaped like a spear. It tapers to a long, thin point and often curls downwards. Sometimes, the tip of the leaf can even grow a small bud, which might rarely turn into a tiny new plant, similar to walking ferns. The main stem of the leaf (called the rachis) is green. The leaf blades are thick and a bit leathery. They are usually 2 to 17 centimeters (0.8 to 6.7 inches) long and 1 to 4 centimeters (0.4 to 1.6 inches) wide. The lobes of the leaf get smaller towards the tip. The veins inside the leaf usually branch out and don't rejoin.
On the underside of a fertile frond, each lobe or segment has one to six clusters of spores, called sori. As they get older, these sori often merge together. They are usually 1 to 2 millimeters (0.04 to 0.08 inches) long. A thin, whitish cover called an indusium protects each sorus. Each tiny spore case (sporangium) holds 64 spores. The Lobed spleenwort has 144 chromosomes in its spore-producing stage (the sporophyte). This high number suggests it formed from two different parent species that combined their chromosomes.
How it Varies
While there aren't different official types of Lobed spleenwort, scientists found an unusual group in Illinois in 1956. In these plants, the leaf blade was very small, almost just the main stem, with only tiny bumps where the spore clusters grew. Sometimes, individual plants might also have split leaves, but this is usually just a random growth change, not something passed down.
How to Identify it
The Lobed spleenwort looks a bit like its parent, the walking fern (A. rhizophyllum). However, the Lobed spleenwort has clear lobes when it's grown up. It also tends to have longer stems compared to its leaf size and grows more upright.
It could also be confused with Countess Dalhousie's spleenwort (A. dalhousiae), but that fern has short, dull stems with larger, toothed scales. The Lobed spleenwort also looks a lot like Scott's spleenwort (A. × ebenoides). But Scott's spleenwort has a stem that is dark all the way up into the main leaf axis, and its leaf lobes are longer.
Plant Family and History
The Lobed spleenwort was first noticed by Henry Muhlenberg in 1813. He thought it was just a type of walking fern. But in 1818, Thomas Nuttall realized it was different and gave it its own species name, Asplenium pinnatifidum.
Scientists later figured out that the Lobed spleenwort is part of a group called the "Appalachian Asplenium complex." This means it easily creates new hybrid ferns when it crosses with other spleenworts. For example, A. × gravesii is a hybrid of Lobed spleenwort and Bradley's spleenwort (A. bradleyi).
In 1951, a scientist named Herb Wagner suggested that the Lobed spleenwort itself might be a hybrid of mountain spleenwort (A. montanum) and walking fern (A. rhizophyllum). He studied the chromosomes of these ferns. He found that Lobed spleenwort has double the chromosomes of its parent ferns. This happens when two different species cross to make a sterile hybrid, and then that hybrid doubles its chromosomes to become fertile. This idea was later supported by other tests, like chemical analysis and genetic studies. These tests showed that Lobed spleenwort likely formed this way in different places.
Besides the hybrids mentioned, Lobed spleenwort is also a parent to other hybrid species. For example, a hybrid between Lobed spleenwort and maidenhair spleenwort (A. trichomanes) was found in 1969 and named A. × herb-wagneri. Scientists have also grown other unnamed hybrids in labs.
Where it Lives
The Lobed spleenwort is native to eastern North America. You can find it in the middle and southern Appalachian Mountains, from Pennsylvania down to Alabama. It also grows in the Shawnee Hills and parts of the Ozarks. You might even find it in southeastern Oklahoma and a small area of Wisconsin.
This fern likes to grow on acidic rocks, often in steep places, from sea level up to about 1,000 meters (3,300 feet) high. It usually grows on sandstone. The soil created from these rocks needs to be somewhat acidic for the Lobed spleenwort to grow well.
Conservation Status
Globally, the Lobed spleenwort is considered "apparently secure." However, it is in danger in many parts of its range. For example, it is considered "critically imperiled" (meaning it's in great danger) in states like Illinois, Maryland, and New Jersey. It's also "imperiled" or "vulnerable" in other states. Things like changes in how land is used, breaking up its natural homes, and certain ways of managing forests can threaten this fern.
Growing it at Home
You can grow Lobed spleenwort in rock gardens or small indoor gardens called terraria. It likes medium light and will grow on moist soil. Some people suggest adding sandstone chips to the soil to help it grow.
Images for kids
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Lobed spleenwort growing in a crevice in schist
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Underside of fertile leaf showing sori.
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Clump of A. pinnatifidum in its typical cliff crevice habitat.
