Native Plants of Hawai‘i - Asplenium kaulfussii

Asplenium kaulfussii

Aspleniacaeae or Spleenwort family

Synonyms: Asplenium bipinnatum, Asplenium enatum, Asplenium enatum var. appendiculatum, Asplenium enatum var. caudatum, Asplenium enatum var. dareoides, Asplenium enatum var. gemmiparum, Asplenium gemmiferum, Asplenium gemmiferum var. enatum, Asplenium gemmiferum var. flexuosum, Asplenium hillebrandii, Asplenium kauaiense, Asplenium kaulfussii f. bipinnatum, Asplenium kaulfussii f. dareoides, Asplenium kaulfussii var. dareoides, Asplenium kaulfussii f. gemmiparum, Asplenium kaulfussii var. gemmiparum, Asplenium kaulfussii var. membranaceum, Asplenium kaulfussii f. paradoxum, Asplenium lucidum, Asplenium lydgatei, Asplenium mannii, Asplenium mannii var. dareoides, Asplenium mannii var. gemmiparum, Asplenium mannii var. kauaiense, Asplenium meiotomum, Asplenium obliquum, Asplenium obtusatum, Asplenium parallelum, Asplenium protensum, Asplenium sectum

Kūau

Kaulfuss' spleenwort, Queen spleenwort, Spleenwort

Natural Range & Environment

HI exc. Ni, Ka

Locally common in mesic to wet forests as terrestrial, epiphytic, and epipetric* plants from about 490 to over 3900 feet on all main islands. [2] Most common in the Waiʻanae Mountains of Oʻahu, rare in the Koʻolau Mountains, rare in sites on Kauaʻi, and much less frequent to rare on other islands (Lānaʻi, East Molokaʻi, Maui, Hawaiʻi).

* An epipetric plant, is one that is found growing on rocks. Many ferns fall into this category of plant habitat, including Asplenium. Epipetric plants are called Lithophytes.

The ripe sori of kūau are arranged in diagonal lines on the underside of its pinnae (Photograph courtesy of Kyhl Austin CC BY-NC 4.0.). Kūau displays a lot of variability in frond shape; here are two extremes (Photograph of thin-pinnae kūau courtesy of Kairigney CC BY-NC 4.0; Photograph of short-pinnae kūau courtesy of Kevin Faccenda CC BY 4.0.). A mature cultivated kūau.

Description

Long lived (Greater than 5 years)

Growth Requirements

General

Accent

Container

Additional Landscape Use Information

Kūau is still uncommon in landscapes in Hawaiʻi, but is worth seeking out from reptuable growers. These lovely ferns do well under the shade of hāpuʻu (Cibotium spp.) and add a different texture in the landscape.

Kūau can be used as a groundcover in shaded areas if planted close together as they can be somewhat slow growing.

Moist

Wet

Soil must be well drained

Partial sun

Shade

Kūau appreciate the morning sun, but should be protected from the hot mid-day and afternoon sun. Fronds grow longer and become dark forest green in the shady conditions.

Soils

Organic

Fertilizer

13-13-13 slow release fertilizer every six months for plants in pots. For larger potted ferns showing poor color or not producing crosiers (fiddleheads or emerging fronds) use a complete fertilizer at half the recommended strength. Do not till solid fertilizers into soil since ferns have a shallow root system. [1]

Pruning Information

Prune off dead fronds fpr clean appearance or leave for natural look in a native garden setting.

Pests and Diseases

In our experience, most pests seem to avoid . Scale and thrips.

Refer to the Pests & Diseases page for how to deal with this pest.

Uses

Ancient Hawaiian

According

Modern

Special Features and Information

General

Kūau (Asplenium kaulfussii) belongs to one of the largest of the fern families Apleniaceae or the Spleenwort family.

There are 28 species of Asplenium ferns native to the Hawaiian Islands, 14 of which are endemic. [2]

Asplenium kaulfussii is a variable species and was formerly divided up into as many as six species and ten varieties. In 2003, the "Hawaiian fern bible" Hawaiʻi's Ferns and Fern Allies by Daniel D. Palmer recognized four distinct forms as follows:

f. bipinnatum. Latin bis, two or twice, + pinnate, in reference to the 2-pinnate fronds. The blades are fully 2-pinnate, pinnules usually resembling small, normal pinnae. Rare and known only form Niu Valley, Oʻahu and has not been collected for decades.

f. dareoides. The name is from Darea, an archaic and currently unused generic name for some species of ferns that have been moved to other genera (including Asplenium), + -oides, like, resembling. The form probably resembles sme former member of that genus. The blades 1-pinnate-pinnatisect to fully 2-pinnate, ultimate segmenst linear with 2 (--4) obtuse teeth on expanded tips. This form was last collected in Kuliʻouʻou Valley on Oʻahu in 1922. Earlier collected in several sites in the Waiʻanae and Koʻolau Mountains on Oʻahu. Previous island distribution is not known because many older collections are simply labeled Sandwich Isles or Hawaiian Islands without specific island designation.

f. gemmiparum. Latin gemma, bud, + parvum, too little, not enough; possibly named in reference to the small proliferations (gemmae) on the pinnae. The pinnae are often with plentiful proliferations on lateral viens of the pinnae. there are variants with very few proliferations. One plant on Maui was observed to have fronds with proliferations at one time and fronds laclikg them at another. This uncommon localized form is known from Kauaʻi, Oʻahu, Lānaʻi, and Maui.

f. kaulfussii. The typical form having pinnae lacking proliferations. The most common form and found on all the main islands.

However, the most current work (2013) for native Hawaiian fern species now places all these forms within Asplenium kaulfussii. [2]

Hawaiian Name

Kūau is the given Hawaiian name for this species. Hawaiian Dictionaries online notes that the name is also used for a "sea creature (perhaps Aplysia sp.)," which is the sea hare, a type of sea slug. [3]

Etymology

The generic name Asplenium is from the Latin asplenum, spleenwort. Ancient Greeks believed that this fern could cure spleen diseases.

The specific epithet kaulfussii is named for George Friedrich Kaulfuss (1786-1830), German botanist and professor of forestry and botany at Halle, who described more than 20 new species of Hawaiian fern species based on Chamisso's* collections from 1816-1817 made during the Russian Kotzebue expedition.

* Ludolf Karl Albert von Chamisso (1781-1838), French-born German explorer, naturalist, author, poet, and plant collector.

Additional References

[1] Kay Lynch, Lāʻau Hawaiʻi.

[2] "Current Status of Ferns and Lycophytes" by Amanda L. Vernon & Tom A. Ranker, pages 96-98.

[3] Hawaiian Dictionaries online http://wehewehe.org [Accessed on 12/4/13]

BPK