Pteridium aquilinum subsp. decompositum

leaf Main Plant Information






  • decompositum

Hawaiian Names with Diacritics

  • Kīlau
  • Kīlau pueo
  • Paiʻā

Hawaiian Names

  • Kilau
  • Kilau pueo
  • Paia

Common Names

  • Bracken fern
  • Hawaiian bracken
  • Hawaiian bracken fern


  • Pteridium aquilinum var. decompositum
  • Pteridium capense var. decompositum
  • Pteris decomposita

leaf Plant Characteristics

Distribution Status


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 1 1/2 to 6 1/2 foot fronds are spaced widely apart by means of a subterrenial (underground) rhizome.

Life Span

No data available.

Landscape Uses

  • Accent

Additional Landscape Use Information

Although commonly seen in its natural habitat, kīlau does not appear to be used much in the urban landscape. But this fern has already proved to be a nice filler plant providing accent texture or provide shading and cooling for plants not tolerant of sunny, hot conditions in landscapes. Kīlau grows a variety of natural habitats and does well in lower elevation gardens, even at near sea level. [David Eickhoff, Native Plants Hawaiʻi]

Kīlau would probably not work well as a landscape groundcover, however, because the Hawaiian variety forms loose colonies, not the dense ground cover found by bracken elsewhere in the world. [1]

Plant Produces Flowers


leaf Leaf Characteristics

Plant texture

  • Coarse

Leaf Colors

  • Dark Green
  • Medium Green

leaf Pests and Diseases

Additional Pest & Disease Information

Locusts have been observed to occasionally feed on fronds, but have limited damage. Caterpillars are sometime found eating new emergant fonds.

leaf Growth Requirements

Pruning Information

Remove dried leaves for clean landscape appearance.

Water Requirements

  • Moist

Soil must be well drained


Light Conditions

  • Full sun
  • Partial sun


  • Organic

leaf Environmental Information

Natural Range

  • Kauaʻi
  • Oʻahu
  • Molokaʻi
  • Lānaʻi
  • Maui
  • Hawaiʻi

Natural Zones (Elevation in feet, Rainfall in inches)

  • Less than 150, 50 to 100 (Mesic)
  • Less than 150, Greater than 100 (Wet)
  • 150 to 1000, 50 to 100 (Mesic)
  • 150 to 1000, Greater than 100 (Wet)
  • 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)
  • 4000 to 4999, Greater than 100 (Wet)


  • Terrestrial

Additional Habitat Information

Kīlau is found on all the main islands, except Niʻihau and Kahoʻolawe from about 985 to around 8860 feet in mesic to wet shrublands, grasslands, and forests, and in some subalpine areas.

leaf Special Features and Information

General Information

Kīlau belongs to the Bracken family (Dennstaedtiaceae) with a worldwide distribution. Pteridium aquilinum is probably the most common fern in the world, found on every continent except Antartica and in dry deserts.

The variety decompositum is endemic to the Hawaiian Islands.


The generic name Pteridium is derived from the Greek pteris, fern, and pteron, wing or feather, in reference to fronds suggesting the spread wings of a bird.

The specific epithet aquilinum, is Latin for eagle (Aquila).

The varietial name decompositum is from the Latin de, very, and compositus, compound, in reference to the frond division.

Hawaiian Names:

The name kīlau is also used for a ti () stalk with shredded leaves, as held by a fishing director (kilo iʻa) and used to guide the fishing canoes; ti stalk used to flip water of purification. [5]

Background Information

Kīlau are one of the few deciduous native plants in the Hawiian Islands. Fronds turn brown and die back in the winter, although rhizomes are still alive. In the early spring, bright green fiddleheads (fronds) emerge. Then by late summer or early, the mature fronds will turn brown and eventually die back by the winter. [4] However, it has been noticed that some lower elevation plants may remain green year round or only some of the fronds may die back. [David Eickhoff, Native Plants Hawaiʻi]

In many countries bracken is often treated as a weed and spoil pastures for grazing animals because of its poisonous properties. [3] However, feral pigs favor the rhizomes and will root up entire patches. [4]

Modern Use

In Hawaiʻi, kīlau is collected and use in wasari. But "because bracken fern has cancerous properties and a nerve poison, it should be eaten infrequently and in moderation." [2]

A substitute for bracken, is the Vegetable fern (Diplazium esculentum), naturalized in Hawaii, and often called hōʻiʻo in local markets. Hōʻiʻo can be prepared the same way as bracken, but "is not known to have these anti-nutritional qualities so it can be eaten freely." [1] The species name esculenta is Latin for edible, alluding to the use of this fern for food. [1]

Outside of the Hawaiian Islands:

Bracken has been used throughout in many cultures around the world. The fiddlehead (immature unfurled fronds) are bitter, but used fresh, cooked, or preserved by pickling, salting, or sun drying. For example, in Korea, called gosari, they are used in bibimbap or gosari-namul, a sauteed side dish; and as a vegetable dish in Japan, called wasari. [2]

Native Americans pound the rhizomes in making a stachy flour for bread; and in Japan used a starch to make confections. [2]

Bracken has been used as fodder for animals, but it can injure or poison them. So, it often used as litter in animal pens. [3]

Additional References

[1] "Edible Plants for Hawaii Landscapes" by UH-CTAHR, pages 3, 4.

[2] [Accessed 8/30/10]

[3] "In Gardens of Hawaii" by Marie C. Neal, pages 15-16.

[4] "Hawai'i's Plants and Animals--Biological Sketches of Hawaii Volcanoes National Park" by Charles P. Stone & Linda W. Pratt, page 257.

[5] [Accessed on 10/16/12]

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