Prickly shield fern facts for kids
Quick facts for kids Prickly shield fern |
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| Scientific classification | |
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Polystichum
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| Species: |
vestitum
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The Polystichum vestitum, also known as the prickly shield fern or pūnui in Māori, is a tough fern that stays green all year round. It grows on the ground and is a common sight in many places.
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About the Prickly Shield Fern
The prickly shield fern grows from a thick, scaly underground stem called a rhizome. This rhizome can sometimes form a short trunk. The fern can grow up to 700 millimeters (about 2.3 feet) tall. Its leaves, called fronds, are usually 220–600 millimeters long.
What the Fronds Look Like
Each small leaf part on a frond is called a pinnule. On the underside of each pinnule, you'll find about 3 to 7 round spots called sori. These sori are where the fern's spores are kept. They are covered by a light brown flap called an indusium.
The fronds usually have two colors. They have a dark brown center with pale brown edges. On ferns found in the Chatham Islands and islands south of New Zealand, the dark brown center might be less noticeable.
Where the Prickly Shield Fern Lives
This fern is native to New Zealand and some nearby islands. You can find it on the North, South, and Stewart Islands of New Zealand. It also grows on the Chatham Islands and New Zealand's subantarctic islands like the Snares, Antipodes, Auckland, and Campbell Islands. It's also found on Australia’s Macquarie Island.
New Zealand Locations
While the prickly shield fern is found on both the North and South Islands of New Zealand, it's not very common north of Auckland or the Coromandel Peninsula in the North Island.
Macquarie Island Habitat
On Macquarie Island, this fern is a main plant in areas called fernbrake communities. These usually grow on the eastern, sheltered sides of the island, in valleys and on slopes. It can form thick patches where not many other plants grow. However, it often grows alongside other plants like Stilbocarpa polaris and Poa foliosa. Rabbits on Macquarie Island enjoy eating this fern, which affects its growth.
Where It Likes to Grow
On the North Island, Polystichum vestitum often covers hillsides and higher, colder areas. On the South Island, it grows in many different places. You can find it near the coast, in mountain areas, and at lower elevations.
This fern is common in open places like valley floors, forest edges, and grassy areas. But it also thrives in cooler, wetter forests.
Life Cycle of the Prickly Shield Fern
Like all ferns, Polystichum vestitum does not produce flowers or seeds. Instead, ferns reproduce using tiny spores. These spores are carried on the underside of their fronds.
How Spores Grow
In springtime, the green fern fronds unroll and stretch upwards. Small green bumps start to appear on the underside of the fronds, which soon turn brown. These spots are called "sori." Each sorus is made of many tiny cases called sporangia, which hold the spores.
When the spores are ready, the sporangia break open. The lightweight spores are then carried away by the wind. Spores can stay alive for many years and travel hundreds of kilometers.
From Spore to New Fern
For a spore to grow, it must land on wet ground. If it lands on dry land, it won't grow because it needs to absorb water. Once a spore settles and absorbs water, it swells and bursts its outer wall. The growing tissue is then released.
This single spore cell divides and grows into a small, heart-shaped plant called a 'prothallus'. It looks a bit like a liverwort plant. On the underside of the prothallus are the male reproductive parts, called antheridia. The female parts, called archegonia, are at the top.
When the sperm and egg are ready, and there's enough moisture, the antheridia release sperm. The sperm are attracted to the egg and swim to fertilize it. Once fertilized, the cell divides, and a new baby fern begins to grow. The prothallus provides nutrients to the young fern. After a while, when the new fern has its own root system and can grow by itself, the prothallus dies. Then, a new life cycle begins as the fern grows to maturity.
What Eats the Prickly Shield Fern
Fern's Food and Habitat Needs
The prickly shield fern prefers soil that drains well, meaning it doesn't get waterlogged. It also likes rich, fertile soil with lots of humus (decayed plant matter). This fern can survive in many different environments. It prefers areas with more rainfall. It can even survive temperatures below 0 degrees Celsius (32 degrees Fahrenheit). In very cold conditions, you'll often find these ferns under the forest canopy, where it's a bit warmer. It likes wetter areas, which is why it's often found in gullies, but it still needs the soil to drain well.
Animals That Eat Ferns
Several creatures like to eat the prickly shield fern. Tiny caterpillars of the "puniu spore-eater" moth live in silk tunnels on the underside of the fronds and eat the spores. Caterpillars from the "pale fern looper" and "zigzag fern looper" moths also feed on the fronds. Deer and possums also enjoy eating this plant.
Common pests that attack ferns include aphids, brown fern scale, other caterpillars, mealy bugs, slugs, and snails. Ferns can also suffer from problems like acid rot, algae, and various fungus diseases.
More About the Prickly Shield Fern
The prickly shield fern is very common, and its conservation status is "not threatened." It has been in this safe category for the past 14 years.
The name Polystichum comes from two Greek words: polus, meaning "many," and stikhos, meaning "rows." This refers to the parallel rows of spore cases found on the underside of the fronds. The word vestitum comes from the Latin word vestire, which means "clothed." This describes the dense covering of scales on the fern's leaf stalks.
