Microlepia speluncae

leaf Main Plant Information

Genus

Microlepia

Species

speluncae

Hawaiian Names with Diacritics

  • Palai nui

Hawaiian Names

  • Palai nui

Common Names

  • Limpleaf fern

Synonyms

  • Davallia andersonii
  • Davallia speluncae
  • Dicksonia flaccida
  • Leptolepia andersoni
  • Microlepia jamaicensis
  • Microlepia strigosa var. hirta
  • Polypodium speluncae

Did You Know…?

This graceful species commonly known as Limpleaf fern, is very similar in appearance to palapalai (Microlepia strigosa). But picking the fronds is a quick way to determine which species is which. The fronds of the limpleaf fern, as its name suggests, go limp soon after being picked, whereas palapalai do not. For this reason while palapalai is greatly used in haku, the limpleaf fern is not useable for lei making.

leaf Plant Characteristics

Distribution Status

Indigenous

Endangered Species Status

No Status

Plant Form / Growth Habit

  • Non-Woody, Spreading

Mature Size, Height (in feet)

  • Fern/Fern-like, Medium, 1 to 3
  • Fern/Fern-like, Tall, Greater than 3

Mature Size, Width

The limpleaf fern have delicate fronds that are 3 to occasionally 10 feet in length and a spread of 4 to 6 more feet.

Life Span

Long lived (Greater than 5 years)

Landscape Uses

  • Accent
  • Container
  • Ground Cover
  • Hedges
  • Screening

Additional Landscape Use Information

An excellent addition to the landscape similar to palapalai but with larger fronds. Limpleaf ferns spread at a slow to medium rate and can be used as a tall ground cover, as an accent under trees or even as a type of fern-hedge. In shadier locations, these ferns can grow quite tall and may be used as a delicate screening plant.

They do well in large planting containers in shade to partial shade with ample moisture. In tall, narrow or smaller pots, place enough rock material in the bottom to prevent the plants from toppling (huli) over in wind gusts. However, limpleaf ferns seem to do best in the ground.

Tips may brown with too much sun or lack of water. But this is a forgiving fern and will come back with new shoots if it has not experienced long periods of drought. [David Eickhoff, Native Plants Hawaiʻi]

An excellent replacement for the non-native, agressive lauaʻe haole (Phymatosorus grossus).

Companion Plants:

This wonderful, full fern that does well under the shade of trees with no foot traffic. Also, limpleaf ferns do not creep up shrubs and trees like lauaʻe haole.

Plant Produces Flowers

No

leaf Leaf Characteristics

Plant texture

  • Coarse

Leaf Colors

  • Light Green
  • Medium Green

leaf Pests and Diseases

Additional Pest & Disease Information

Generally, few pests bother this fern. Caterpillars and slugs will occasionally chew on the fronds. [5]

leaf Growth Requirements

Fertilizer

In pots, it appreciates a 13-13-13 slow release fertilizer every six months. Potted ferns showing poor color or not producing crosiers (fiddleheads or emerging fronds), use a complete fertilizer at half the recommended strength. [2,5] Do not till solid fertilizers into soil because the ferns have a shallow root system. [2]

For ferns planted in the ground, composted manure is another suggested fertilizer. [3]

Pruning Information

For a clean appearance, trim off old fronds that turn brown. Trim near the base but be careful not to injure new fronds, or fiddles, since they grow so close together.

Otherwise, to keep a natural look fronds can be left on the plants and will eventually fall off and enrich the soil. Richard Quinn, landscape architect in Hawaiʻi, notes that "native ferns like Pala nui can be an important component of an ecosytem approach to using native plants in landscping. Native fern roots and fern leaf litter form important associations with mycorrhizae and bacteria that presumably could help to create a soil profile that could benefit other native plants." [5]

Water Requirements

  • Moist
  • Wet

Additional Water Information

Best grown with constant moisture but not wet. [3]

Richard Quinn suggests "a moderate amount of water, less than Hapuʻu, more than Kupukupu, but can be drought tolerant for short periods of time and recover. In a typical urban garden setting, it will probably do best with about three waterings a week." [5]

Soil must be well drained

Yes

Light Conditions

  • Partial sun
  • Shade

Additional Lighting Information

Fronds will have a nice fresh green color to them and plants will over all perform better with some shading, but does tolerate some full sun for a few hours. [David Eickhoff, Native Plants Hawaiʻi]

Tolerances

  • Drought

Soils

  • Clay
  • Cinder
  • Organic

Limitations

Appears to be drought tolerant for short periods of time, [5] but will perish in extended periods. [David Eickhoff, Native Plants Hawaiʻi]

Does not tolerate foot or pet traffic. [5]

This fern is best grown in lower elevation humid conditions and does not tolerate cool temperatures lower than 59°F. [3,4]

Special Growing Needs

Limpleaf ferns thrive and will grow to its greatest potential in loose rich, slightly acid soil with good organic material with partial shade and ample moisture. [5, David Eickhoff, Native Plants Hawaiʻi]

Mulching is also recommended to help hide any bare dirt and give it a finished look in the landscape. Mulch also helps to conserve moisture and adds nutrients to the soil. [5]

Moderate wind protection is also suggested. [5]

leaf Environmental Information

Natural Range

  • Kauaʻi
  • Oʻahu
  • Molokaʻi
  • Maui
  • Hawaiʻi

Natural Zones (Elevation in feet, Rainfall in inches)

  • 1000 to 1999, 50 to 100 (Mesic)
  • 1000 to 1999, Greater than 100 (Wet)
  • 2000 to 2999, 50 to 100 (Mesic)
  • 2000 to 2999, Greater than 100 (Wet)
  • 3000 to 3999, 50 to 100 (Mesic)
  • 3000 to 3999, Greater than 100 (Wet)
  • 4000 to 4999, 50 to 100 (Mesic)

Habitat

  • Terrestrial

Additional Habitat Information

In the Hawaiian Islands, this indigenous fern is occasionally common in spots on some of the main islands, especially in the Waiʻanae Mts., Oʻahu, from 1575 to 4200 feet in mesic to wet forests.

The limpleaf fern is also found from South China, the Himalayas, India, Sri Lanka, the Malay Peninsula, Japan, Taiwan, The Philippines to Polynesia and is the only species in the genus native to Africa. While it extends to the American Tropics, it is probably not native there.

Though this species has a widespread distribution outside of the Hawaiian Islands, it is not as common as its cousin palapalai (M. strigosa) within the islands.

leaf Special Features and Information

General Information

Limpleaf fern belongs to a worldwide group of about seventy Microlepia species in the Bracken fern family (Dennstaedtiaceae). [1]

There are two indigenous species, the other being palapalai (M. strigosa), and a hybrid known on the main Hawaiian Islands.

The most famous family member is the bracken fern (Pteridium aquilinum), known kīlau in the Hawaiian Islands, which is perhaps the worlds most common fern.

Etymology

The generic name Microlepia is derived from the Greek mikros, small, and lepis, scale, alluding to the small cuplike indusia (spore covering) of this genus.

The specific epithet speluncae is from the Latin, spelunca, cave, grotto or den, perhaps named for the first habitat where it was collected.

Hawaiian Name:

While there is no known Hawaiian name for this species, Pala nui has been used locally for this fern. Palai nui means "big fern." [5]

Background Information

Microlepia speluncae, commonly known as Limpleaf fern, is very similar in appearance but usually has larger, sometimes much larger, fronds. As mentioned earlier, picking the fronds is a quick way to determine the species. The fronds of M. speluncae soon go limp after being picked, whereas M. strigosa do not. [1] Too, at close examination or just by touch, M. strigosa has small bristlelike (Latin, striga) hairs on leaves; whereas M. speluncae do not and are glabrous (without hairs).

There is also a hybrid between the Microlepia speluncae x M.strigosa that has given the interesting Latin name Microlepia x adulteriana. [1] The name implies an adulterous relationship between the two parental species. The hybrid forms large colonies where the two species are found together.

Early Hawaiian Use

Undoubtedly early Hawaiians were aware of these large ferns, but no use for them has been found nor is a name known as yet.

Modern Use

Limpleaf ferns are rarely seen in landscapes or botanical gardens in Hawaiʻi. However, with greater awareness and availability, it is hoped this spectacular large native fern will become more commonly seen in home gardens and commercial landscapes.

Additional References

[1] http://homepages.caverock.net.nz/~bj/fern/microlepia.htm [Accessed 10/16/09]

[2] Kay Lynch, Lāʻau Hawaiʻi

[3] "Encyclopedia of House Plants" by Nico Vermeulen & Richard Rosenfeld, page 20.

[4] http://www.gardening.eu/arc/plants/Apartment-Plants/Microlepia-speluncae-L.-T.-Moore/44412/stamp_a.asp [Accessed 4/15/11]

[5] "Palai Nui--An Overlooked Fern" by Richard Quinn in "Hawaii Landscape" Sept./Oct. 2013 issue, pages 15 & 23.

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