Laua’e: Scented Hawaiian Ferns
Triangular Functions
by Jay Vannini
After hundreds of years of being among the most prized plant groups by gardeners, ferns remain a solid favorite in ornamental horticulture today. The popularity of ferns in terraria, gardens, greenhouses, and interiors really is “evergreen”.
Mixed native maidenhair fern (Adiantum capillus-veneris and A. aleuticum) mass planting designed by the author. Private garden, San Mateo County, California, USA. Image: ©Jay Vannini 2025.
The fern flora of the continental U.S.A. (~400 species) contains many native genera that are eagerly sought by collectors and landscapers alike. Given its phytogeography, a large number of them originate from mesic ecosystems on both coasts. Florida and Hawaii are noteworthy for their fern diversity and are home to almost two-thirds of all native species. The most commonly cultivated ornamental genera from temperate regions include Nephrolepis, Adiantum, Polystichum, Dryopteris, Polypodium, and Athyrium. Representatives of most of these genera that are suitable for mass market are propagated via rhizome divisions or plant tissue culture in laboratories and may be found offered for sale at any well-stocked online fern nursery, garden center, or big box store.
Noteworthy native tropical species grown in some sheltered North American gardens and conservatories also include a number of tree fern species (Cyatheales) that are found in Hawaii, southern Florida, and U.S.A. possessions such as Puerto Rico and the Virgin Islands.
Beyond these popular garden forms, there are a half-dozen or so lesser-known native ferns with very specific environmental and cultural requirements that are grown by avid fern specialists.
Desert dwelling ferns are surprisingly common in parts of the southwestern U.S.A and are especially diverse in rocky upland areas of west Texas and southern Arizona. Native xerophytic ferns, while still mostly the province of regional botanical gardens, are slowly gathering a following among stem succulent and specialty fern growers outside of their native ranges. Several native species of Hemionitis, Notholaena, and Astrolepis have been established in cultivation, may readily be found for sale online, and are surprisingly attractive accent pieces suitable for drip irrigated rock gardens and pots in the Southwest. Wild collection of protected desert fern species is illegal and removal of any xerophytic fern from nature by hobbyists is strongly discouraged in any case.
Two USA and Mexican native desert and dry country ferns growing fully exposed in cultivation in California. Above left, the Wavy Scaly Cloakfern, Astrolepis sinuata, and right, Lindheimer’s Fairy Sword, Hemionotis (formerly Cheilanthes) lindheimeri. Images: ©Jay Vannini 2025.
The remaining two species are oddballs with unusually shaped fronds that are restricted to wet tropical ecosystems and are among the least-known U.S.A. native ferns.
The Hand fern, Ophioglossum palmatum L., is now a rare and localized epiphyte in southern Florida but widespread and often locally common throughout the Caribbean and northern Neotropics. Some select frond forms are attractive, but many are rather unremarkable-looking. While I do house a pair of Asian Ophioglossum species in California, I have not attempted to grow this species either here nor in Central America; wild-collected material is said to be difficult to succeed with in cultivation.
The other is the subject of this article, the Laua’e or Pe’ahi, Microsorum spectrum (Kaulf.) Copel. (Polypodiaceae).
This is a somewhat showy, terrestrial or hemiepiphytic fern with two recognized varieties (POWO, 2025). It is endemic to all the major Hawaiian Islands that is apparently extirpated from many of its former haunts but still observed as a rarity on O’ahua, Kaui, and Molokai. Microsorum spectrum var. pentadacylum (Hillebr.) D. D. Palmer is a three to five-lobed, “ivy” or “sweetgum-leaf” form that is restricted to the island of Kaui (Palmer, 2002). A possibly chimeric, subpinnate-leaf population was reported from a single population on Maui (Palmer, 2003), but may occur elsewhere since I have a specimen with lanceolate to partially-lobed fronds grown from spore whose siblings possess normal frond shapes. This species is an inhabitant of shady, wet forest understory with a reported elevational range from 590’ to 3,450’/180-1,050 masl.
Laua’e is the common name in widest use; Pe’ahi is its native name on Maui. It has been called the Triploid Fern in some publications although available data indicates that they are actually tetraploids with a count of 2n = 144 or 2n = 148. Based on a single genetic sample from a var. pendactylum, hybrid origin has been suggested as a possible route to its speciation, but no no putative parents were proposed and this hypothesis has not gained traction as far as I can see (Nitta et al., 2018; pers. obs.). Microsorum spectrum is, at this time, considered the sole indigenous representative of the genus in Hawai’i.
Microsorum spectrum is a fairly compact fern species with single fronds usually <9”/22 cm in length although some exceptional fronds on var. pentadactylum reach >14”/35 cm overall.
Microsorum spectrum photographed growing as a terrestrial in nature at an undisclosed locality in Hawaii. Image: ©Hubert Szcsygiel, Creative Commons by-nc/4.0.
Mistaken Identity
This is one of several Maile- (Alyxia stellata [J. R. Fort. & G. Forst] Roem & Schult. - Apocynaceae) scented Polynesian ferns. Indigenous Lauae or Laua’e was translated as an “an aromatic herb”, or “a variety of fern, very fragrant and used for decorative purposes”, in early Hawaiian dictionaries and lists of names for native plants (Anderson-Fung, 2023).
Confusingly, the common name Laua’e is also used for a non-native fern species that is now used in traditional Hawai’ian ceremonies after replacing Microsorum spectrum.
The Musk Fern, Microsorum grossum (Langsd. & Fisch.) S. B. Andrews, formerly known as Phymatosorus grossus (Langsd. & Fisch.) Brownlie, is an eastern Australian and southern Pacific insular species that was long believed to be native to the state. To muddle matters even further, Hawaiian introductions, also known as Laua’e, are sometimes mistakenly reported as M. scolopendria (Burm. fil.) Copel. in the literature. The Musk Fern is now known to have been introduced to the Islands during the early 20th century and was reported to be naturalized in many places in Hawai’i by 1922 (Wilson, 1996). Now ubiquitous in the islands, it is a well-known invasive plant in Hawai’i that is nonetheless widely appreciated for its attractive fronds and fragrance, which is described as being almond- or vanilla-like (Neal, 1965; Palmer, 2003).
The Genus
Microsorum (Polypodiaceae: Microsoroideae – 33 species) are mostly tropical ferns, although a few species occur in temperate zones of South Africa, Asia, Australia, and New Zealand (POWO, 2025). At least one of these, M. diversifolium (Willd.) Copel., hitch-hiked to the UK and Ireland on imported tree fern trunks and is reported to be locally naturalized at some spots where these have been planted (Rickard, 2000). Other subtropical and tropical species have been trialed outdoors in subtropical areas of Florida and southern California but invariably perish when exposed to even brief frosts.
Of special note there are two blue-iridescent and warm-growing, mostly lithophytic southeast Asian species known as oil ferns that are extremely popular with rare tropical plant collectors: Microsorum siamense Boonkerd and M. thailandicum Boonkerd & Noot. Both require high humidity and attention to detail to thrive in cultivation (pers. obs.). A hybrid between the two was released several years back by several Thai nurseries.
Above left, a greenhouse grown Microsorum thailandicum thriving in a mixed mineral and bark substrate and right, M. siamense start planted in pure, fine-grade akadama. Author’s plants. Images: ©Jay Vannini 2025.
Conservation Status
This fern was still considered reasonably abundant in the islands during the latter half of the 19th century (Anderson-Fung, 2023). Habitat loss and over-collection for the production of leis in the pre-modern era likely contributed to its now fragmented populations and current “imperiled status”. Information in a Hawaiian plant conservation paper published a decade back estimated that only 250 mature ferns remained in nature at that time, of which 50 were targeted for future collection for ex-situ conservation projects (Keir & Weisenberger, 2014).
Concern about collection of wild plants has led online herbaria and photo banks to conceal locality data from potential poachers. While rarely–if ever–available in international commerce these days, it is likely offered by those nurseries in Hawaii that specialize in distributing rare native plants. Botanical Gardens Conservation International’s PlantSearch shows six affiliated collections growing this species as of January 2025.
Cultivation
In my experience this unusual fern has a deserved reputation for being challenging to grow outside of native conditions. While there are some lowland populations, it appears that cultivated plants originated from higher elevation accessions and seem to require cooler nights and pure water to thrive. That said, I have found that shifting my plants from a cool and sometimes chilly cloud forest greenhouse that was originally recommended to me to different spots a warm and wet tropical house has greatly improved their appearance and vigor.
They seem to be water quality sensitive and will brown tip quickly when over-fertilized. I prefer to err on the side of caution and recommend use of pure water (i.e., rain-, RO, or distilled) for irrigation and light feeds of water soluble fertilizers every fortnight at ~50-75 ppm total N.
Young frond on a cultivated Microsorum spectrum grown from spore produced under greenhouse conditions in Florida during the past decade. Producing clean, healthy fronds in this species requires careful attention to watering and fertigation. Author’s plant. Image: ©Jay Vannini 2025.
Lanceolate frond form in a cultivated Microsorum spectrum in the author’s collection. This particular plant produces a variety of unusual leaf shapes, including lanceolate, rhomboidal, and deltoidal. Compare with image below. Image: ©Jay Vannini 2024.
Over the past seven years I have trialed them in a variety of substrates and found that under my conditions Microsorum spectrum grow well in pure, shredded New Zealand tree fern fiber. While starts and smaller plants may be potted in small containers, the long, slender rhizomes of specimen plants like to run and should be planted out in a suitably sized bulb pan or bonsai tray. Likely due to its occasionally hemiepiphytic growth habit, rhizome sections root easily in deep pots filled with New Zealand sphagnum moss and this may prove to be an excellent choice as a permanent growing medium for specimens as well. This is a slow growing fern, and patience is required to get them to specimen size.
Young fronds are attractive to both thrips and aphids, so keep a close eye out for these pests when new fronds are emerging. Slugs and snails may also be a headache when these ferns are grown in in perma-wet environments.
Despite its slow growth, this handsome fern would make for a unique low ground cover in shady, sheltered spots of rainy tropical gardens or climate controlled conservatories for those with the time and patience to make this work.
While invariably referred to as pleasantly fragrant in nature (Anderson-Fung, 2023), I have been unable to detect any scent other than a grassy or dry hay-like one in either living, freshly crushed, or dried fronds of any of my Microsorum spectrum. This is rather surprising since it is reported by local botanists and others that it has a smell similar to Maile, so presumably one resembling vanilla. Once used to make ceremonial leis, Laua’e fronds were also used to infuse coconut oil that was later applied to items of native clothing such as those made from kapa/bark cloth (Anderson-Fung, 2023).
I strongly suspect that there is a micronutrient (or mycorrhizal fungus?) lacking in my substrates that is a key precursor for the volatile that produces the seductive scent that Laua’e is famed for in nature.
Outside of certain state-sponsored nurseries in Hawai’i, this seems a rather difficult plant to source. It is poorly known in cultivation and, indeed, is not even mentioned in the encyclopedic “Fern Grower’s Manual (Hoshizaki & Moran, 2001). Rather ironically, my founder specimens were small starts grown from spore harvested off plants in the former collection of Charles Alford and collected by famed fern grower, taxonomist, and author Barbara Joe Hoshizaki. Unfortunately, I have been unable to determine the locality where the original accession was collected. After her death Dr. Hoshizaki’s living collections were distributed to other fern growers, mostly in California (R. Moran, pers. comm.).
If anyone in SoCal has a tag with her original accession data on it or knows where the founders were collected in Hawai’i, I’d like to hear from you.
Acknowledgments
Fern specialists Charles Alford and Dr. Robbin Moran provided background information–or the lack of–on the original Barbara Jose Hoshizaki Microsorum spectrum accession. The image of a plant growing as a terrestrial at an undisclosed locality in nature is not copyrighted in this non-commercial use case, and is licensed by Hubert Szczygiel and Creative Commons 4.0.
References
Allen, D. E. 1969. The Victorian Fern Craze: A History of Pteridomania. Hutchison, London. 83 pp.
Anderson-Fung, P. 2023. The tale of Hawai’i’s two scented laua’e, Microsorum spectrum and Microsorum grossum: Solving the mystery of their history and restoring indigenous knowledge, using the synergism of Linnaean and Polynesian taxonomy. Ethnobotany Research and Applications. 26:20. 43 pp. https://ethnobotanyjournal.org/index.php/era/article/view/5229/1777
A thorough examination of the confusion surrounding the true identity of native laua’e, their ethnobotany, and a discussion of other Hawaiian scented ferns.
Hoshizaki, B. J. and R. C. Moran. 2001. Fern Grower’s Manual. Timber Press, Portland, OR. 624 pp.
Keir M. and L. Weisenberger, 2014. Hawai’i Strategy for Plant Conservation. Phase I; increasing in situ collecting and ex situ capacity. 102 pp. https://laukahi.org/wp-content/uploads/2021/06/Hawaii-Strategy-for-Plant-Conservation_AUG-28-2014.pdf
Neal, M. C. 1965 (1984). In Gardens of Hawaii. Fifth Printing. Special Publication 50. Bishop Museum Press. xix + 924.
Nitta, J. H., S. Amer, and C. C. Davis. 2018. Microsorum x tohieaense (Polypodiaceae), a New Hybrid Fern from French Polynesia, with Implications for the Taxonomy of Microsorum. Systematic Botany, 43 (2): 397-413
Nooteboom, H. 1997. The microsoroid ferns (Polypodiaceae). Blumea 42: 261-395.
Palmer, D. 2002. Taxonomic Notes on Hawaiian Pteridophytes. American Fern Journal. Volume 92, No. 2: 95-104.
Palmer, D. 2003. Hawaii’s Ferns and Fern Allies. University of Honolulu Press. ix + 325 pp.
Rickard, M. 2000. The Plantfinder’s Guide to Garden Ferns. David & Charles/Timber Press, Portland, OR 192 pp.
Royal Botanical Gardens Kew – Plants of the World Online (POWO). 2024. Accessed January 2025. Link: https://powo.science.kew.org/
Wilson, K. A. 1996. Alien Ferns in Hawai’i. Pacific Science 50, no. 2: 127-141. https://scholarspace.manoa.hawaii.edu/server/api/core/bitstreams/27028f83-9ef7-4829-b8f8-6df112dd888f/content
All content ©Exotica Esoterica LLC® 2025, ©Jay Vannini 2025, and ©Hubert Szczygiel licensed under http://creativecommons.org/licenses/by-nc/4.0/
