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Marsilea villosa

leaf Main Plant Information

Genus

Marsilea

Species

villosa

Hawaiian Names with Diacritics

  • ʻIhi lāʻau
  • ʻIhiʻihi
  • ʻIhiʻihi lāʻau
  • ʻIhiʻihilauākea

Hawaiian Names

  • Ihi laau
  • Ihiihi
  • Ihiihi laau
  • Ihiihilauakea

Common Names

  • Hawaiian pepperwort
  • Hawaiian waterclover
  • Hawaiian waterfern
  • Villous waterclover

leaf Plant Characteristics

Distribution Status

Endemic

Endangered Species Status

Federally Listed

Plant Form / Growth Habit

  • Non-Woody, Spreading

Mature Size, Height (in feet)

  • Fern/Fern-like, Short, Less than 1

Mature Size, Width

ʻIhiʻihi has a spread of 10 feet or more.

Life Span

Long lived (Greater than 5 years)

Landscape Uses

  • Accent
  • Container
  • Ground Cover
  • Water Features

Additional Landscape Use Information

Even though this fern lives naturally in vernal pools, it is not necessary to go through the wet/dry seasonal cycle to grow it successfully in a landscape setting. [David Eickhoff, Native Plants Hawaiʻi]

The wet/dry seasonal cycle is required though to set seed (spores) in its natural habitat. [1] Still, they will occasionally set seed spore even under very wet cultivated conditions. [David Eickhoff, Native Plants Hawaiʻi]

ʻIhiʻihi is easy to grow and spreads rapidly with good moisture. This water loving fern can be used in and around ponds and other water features. Use in full sun or part sun locations as a unique groundcover. Does not do well in deep shade. They also look nice in standard pots or in hanging baskets.

Plant Produces Flowers

No

leaf Leaf Characteristics

Plant texture

  • Fine

Additional Plant Texture Information

ʻIhiʻihi leaves (blades or fronds) are shaped like a four-leaved clover or shamrock and its upper and lower surfaces are covered with fine white hairs. The species name "villosa" meaning "hairy" refers to the hairs on the leaves, rhizomes and sporocarps (spore containing case).

Leaf Colors

  • Medium Green

Additional Leaf Color Information

Leaves can take on a reddish hue when grown in full sun.

leaf Pests and Diseases

Additional Pest & Disease Information

ʻIhiʻihi is subject to attacks by slugs, ants, mealy bugs, scale, thrips, aphids, root mealy bugs and scale.

leaf Growth Requirements

Fertilizer

Small applications of a balanced slow release fertilize with minor elements every six months is fine unless ferns are grown in ponds or other water features. Watch for signs of too much algae in the water, which could indicate too much nitrogen. [David Eickhoff, Native Plants Hawaiʻi]

If grown on land. foliar feed monthly or every other month with kelp or fish emulsion, or a water-soluble fertilizer with a dilution of one half to one third of recommended strength to maintain good health. [David Eickhoff, Native Plants Hawaiʻi]

Pruning Information

Usually very little pruning is required if plants are kept hydrated. These ferns will die back if soil dries out. [1]

Water Requirements

  • Dry
  • Moist
  • Wet

Additional Water Information

Naturally ʻihiʻihi is dormant during periods of drought appearing as a mat of rhizomes. The rainy winter months will produce standing pools of water and the leaves will then produce rapidly.

However, such wet/dry periods are not required for growing ʻihiʻihi successfully under cultivation. Still, they usually perform better under moist to wet conditions. [David Eickhoff, Native Plants Hawaiʻi]

Soil must be well drained

No

Light Conditions

  • Full sun
  • Partial sun

Additional Lighting Information

Too much shading reduces overall vigor of ʻihiʻihi. [1] Also, id grown in full sun may produce smaller and redder fronds (foliage). Therefore, partial sun seems to be the best choice. [David Eickhoff, Native Plants Hawaiʻi]

Spacing Information

ʻIhiʻihi naturally spread by rhizomes. They can be planted out as small clumps 6 to 12 inches or more apart or place rhizomes in shallow trenches. [David Eickhoff, Native Plants Hawaiʻi] Either way they are planted, the rhizomes will soon grow together forming a dense interwoven mat. [1]

Tolerances

  • Waterlogged Soil
  • Drought
  • Wind

Soils

  • Clay
  • Organic

Limitations

Plants are somewhat salt tolerant. [David Eickhoff, Native Plants Hawaiʻi]

leaf Environmental Information

Natural Range

  • Niʻihau
  • Oʻahu
  • Molokaʻi

Natural Zones (Elevation in feet, Rainfall in inches)

  • Less than 150, 0 to 50 (Dry)
  • 150 to 1000, 0 to 50 (Dry)

Habitat

  • Aquatic
  • Terrestrial

Additional Habitat Information

ʻIhiʻihi, or ʻihiʻihilauākea, has disappeared from historical sites such as Kaimukī in Honolulu due to urban development. This endangered fern now only grows naturally at Makapuʻu, ʻIhiʻihilauākea Crater and Koko Head in southern Oʻahu; Lualualei Valley in western Oʻahu; and Kamakaʻipo and Mokio on Molokaʻi. It is thought to be extinct on Niʻihau (Loʻe Lake) and northwestern Molokaʻi (Moʻomomi and ʻĪlio Pt.). [1] ʻIhiʻihi naturally grows in rocky areas with no standing water.

leaf Special Features and Information

General Information

ʻIhiʻihi belongs to a group of unusual ferns that do not look like ferns but rather like four-leaved clovers (Trifolium spp.) or shamrock (Oxalis spp.), both of which are totally unrelated plants. But ʻihiʻihi are indeed ferns belonging to Marsileaceae, a family with about 65 species worldwide.

In its natural habitat ʻihiʻihi goes dormant during drought and appears as a mat of dry rhizomes. In the winter when it rains it brings standing water and the rhizomes produce leaves rapidly. In periods of flooding the leaves float on water surface.

Etymology

The generic name Marsilea is named for Count Luigi Ferdinando Marsigli or Marsili (1656-1730), Italian botanist at Bologna.

The Latin specific epithet villosa, hairy, in reference to the hairy rhizomes and sporocarps.

Modern Use

ʻIhiʻihi has been used in some landscapes as a drought tolerant groundcover. Often it has been sold on the market as "Shamrock" or "Four-leaf Clover."

It is hoped that this native fern will be used more in the landscapes as it is a federally endangered species and is easy to maintain.

Additional References

[1] "Recovery Plan for Marsilea villosa" by USFWS, pages 1, 7-8, 9-10, 12.

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