Native Plants of Hawai‘i

Psilotum nudum

Psilotaceae or Whisk fern family

Synonyms: Lycopodium nudum, Psilotum nudum var. oahuense, Psilotum oahuensis, Psilotum triquetrum

Moa

Moa nehele, Oʻō moa, Pipi

Cocks crow, Forest moa, Skeleton fern, Skeleton fork fern, Upright whiskfern, Wisk fern

Natural Range & Environment

Psilotum nudum has a wide pantropical and subtropical distribution, and is found across North, Central, and South America, Africa, Asia, Australia, and parts of the Pacific, including Hawai‘i and New Zealand. There are also a few isolated populations in Southwestern Europe [iNaturalist].

In Hawai‘i, Psilotum nudum can be found on Pihemanu (Midway Atoll) as well as all the main Hawaiian Islands. It can be seen from near sea level to 1,200 m (3,937 ft), growing in many dry to wet habitats on rocks and lava flows, in soil, and frequently on trees [Palmer 2003]. It is also a common "weed" in urban areas, often growing in unexpected places such as flowerpots and cracked walls.

The cut stems of moa can be used as a long-lasting component of floral arrangements, or placed on a sheet of paper in a dry draft-free place for a couple of days to collect their spores; the spores can then be spread around your landscape (e.g., onto a rock wall, into the pot of an established plant). Alternatively, propagate moa by gently collecting and transplanting a portion (with both rhizomes and new stems) of an existing plant (Photographs of cut stems and transplant courtesy of Greg Koob©.). Just three examples of the many places you can display your moa: as an accent mixed with other native Hawaiian plants (Photograph courtesy of Daderot Public Domain); growing from the cracks in a rock wall (Photograph courtesy of Jordan Loftin CC BY-NC 4.0.); as a container companion to other plants (Photograph courtesy of Greg Koob©.). Not often seen together, here a wild Psilotum nudum (right) and Psilotum complanatum grow side by side (Photograph posted with permission of Matthew Walters.).

Description

Psilotum nudum is a small to medium-sized (up to about two feet [61 cm] tall) fern-relative with a lifespan greater than five years. Its unusual sticklike leafless morphology makes it easy to identify. Moa has upright spreading stems that can be up to two feet (61 cm) long with a triangular cross-section. As the stems grow, they regularly divide into two new branches. The stems are most often green, but can be partially yellow to orange if frequently exposed to sunlight or as they age.

On its stems, moa has tiny scalelike appendages called "enations," which may be reduced leaves; however, enations lack any veins. Also on its stems, moa develops three-lobed synangia. Each of the lobes is a sporangium, a capsule where the reproductive spores develop. The sporangia turn yellow and then burst open to release their spores when they are mature [Palmer 2003].

Moa lacks roots and instead has rhizomes (i.e., subterranean stems) with smaller rhizoids that help anchor the plant. The rhizoids are connected to mycorrhizal fungi, which help transport water and nutrients to the plant as a kind of substitute root system. This association begins early for moa, all the way back during the tiny subterranean gametophyte phase of its lifecycle; the plant we see is the sporophyte phase. As a gametophyte, moa is non-photosynthetic and completely dependent upon its mycorrhiza fungi for energy-containing nutrients [In Defense of Plants].

For many years, because whisk ferns appear so morphologically and reproductively "simple," many botanists thought the genus Psilotum might be a "living fossil," a connection to the early days of vascular plants. However, a more detailed examination of their morphology and recent molecular studies clearly show that whisk ferns reside within the fern lineage. And, that it is more likely whisk ferns represent a reduction in the more traditional fern form rather than a holdover of ancient terrestrial plants [In Defense of Plants].

Growth Requirements

General

Perhaps, it's because Psilotum nudum "magically" appears in so many unexpected places, such as the crotch of a tree, the cracks in a rock wall, or the drainage holes of another plant's pot, that Hawai‘i's residents are often surprised to learn (or have forgotten) that moa is a native Hawaiian plant (with a rich cultural history). We can only hope that as more people do learn, they consider planting or keeping moa in more traditional places within their residential and community landscapes. Within those landscapes, moa does well as a terrestrial (i.e., in-the-ground) accent among other native Hawaiian plants, atop a pile of rocks or on a cracked lava boulder, or in a container (with or without a companion plant) indoors or out. Interestingly, moa in pots tend to maintain a maximum size depending upon the size of the pot; small pot = small moa while large pot = large moa.

Probably because Psilotum nudum is difficult and time-consuming (up to three years [Hawaii Horticulture]) to grow from spores, you don't often find it for sale. One way to buy one is to explore the forgotten corner of your local nursery, the place where all the older, sometimes uglier, plants have migrated, and look for a moa that has invaded the pot of one of these forgotten plants. (Maybe, you can convince the nursery owner to sell you the plant for half price!) Another, way to obtain a moa is from a friend or neighbor that has one. Ask them if it would be okay if you took a small portion of their plant to start as your own. If they say "yes," you don't need much, but you do need to make sure the potion you take has both some rhizomes and a few new pointed white to green stem tips (see the photograph above). Repot the transplant in a clean (i.e., new) easy-draining organic plus inorganic media mix (e.g., sphagnum peat moss and perlite), making sure the transplant is at the same depth it was in the host plant's pot (or ground). If there are any original stems still attached to your transplant, leave them (even if they are unsightly) since cutting them off can dramatically reduce the chances of your transplant surviving [Hawaii Horticulture]. Place your transplant in a shaded site and keep the media moist. Once your new moa starts growing new stems, you can start considering where its final home will be. However, be patient, since this transplant and recovery process can take months.

Moa has a wide light tolerance, and can grow in a site that receives full sunlight for all or most of the day or in a site that is constantly shaded (or, of course, anywhere in between). Plants grown in direct sunlight tend to be partially yellow or orange, while those in constant shade are typically a dark green. (Don't mistake the orange or yellow coloration for a disease or ill health. It's just a natural adaptation to the sunlight.)

It's best to keep the soil or media surrounding your moa moist (but well-drained) at all times. However, established plants can withstand mild drought conditions for a short time. Moa can endure strong winds and extreme heat (provided its rhizomes don't dry out). However, according to the College of Tropical Agriculture and Human Resources at the University of Hawaiʻi at Mānoa, moa has poor salt tolerance [CTAHR]. We have grown moa in lava/cinder, clay, and organic-dominant soils.

Moa typically grow pretty slowly; however, light fertilization may speed this up a bit or improve the plant's color [Hawaii Horticulture]. You can expect to see your moa start to develop sporangia pretty early (i.e., within a year) when it is still quite small. While the stems of moa live a long time, they don't last forever. Therefore, to keep your plant looking tidy, you can remove these dead stems by hand-pruning.

Pests and Diseases

Moa doesn't seem to be bothered much by pests or diseases. However, you may discover root mealybugs within the pot of an ill-kept (e.g., too wet media) plant. Refer to the Pests & Diseases page for ways to eliminate root mealybugs.

Uses

Ancient Hawaiian

Moa had several uses in ancient Hawai‘i. The stems were used in lei [Krauss 1993], while the spores were used (like talcum powder today) to prevent chafing from a loincloth [Neal 1965; Palmer 2003]. Krauss [2001] describes moa being used to make a tea which was drunk after or in combination with other medicines for treating asthma and chest pains. Neal [1965] also notes that a tea brewed from the whole plant has cathartic properties.

However, the most interesting ancient use of moa was in a children's game called moa nahele. Krauss [1993] describes how the game was played.

Two children sat or stood facing one another, each holding a branched stem of moa. These they interlocked and then slowly pulled apart until the branches of one broke. The other child, without broken branches, was the winner and announced his victory by crowing like a rooster (moa).

Appropriately, one of Psilotum nudum's alternative Hawaiian names is ʻoʻō moa, which means "cock's crow."

Modern

Today, moa is still used for neck, head, wrist, ankle, and horse leis [CTAHR]. It is also used in floral arrangements, and may prolong the display life of other flowers [Hawaii Horticulture].

Special Features and Information

General

Psilotaceae is a family of fern-like plants consisting of two genera, Psilotum and Tmesipteris, with about a dozen species. Once thought to be descendants of early (and ancient) vascular plants, recent molecular studies place Psilotaceae firmly within the class Polypodiopsida (i.e., ferns) [WikipediA;Psilotaceae].

The genus Psilotum has only two widespread species: Psilotum complanatum and P. nudus, and one hybrid between the two, Psilotum x intermedium. Both species are indigenous to Hawai‘i, while the hybrid may be endemic. The characteristic features used to identify the three are:

Psilotum complanatum has arched, drooping stems that are flat in cross-section, with two parallel rows of sporangia on opposite sides of the branchlets.
Psilotum nudum has upright (typically non-arched) stems that are triangle-shaped in cross-section, with three rows of sporangia on the ridges of the branchlets.
Psilotum x intermedium has a morphology intermediate between the two parent species [Palmer 2003].

Hawaiian Name

Both Psilotum nudum and P. complanatum are called moa or moa nahele, as well as pipi, in the Hawaiian language [Palmer 2003]. Therefore, to distinguish between the two species within this website, we have chosen to use moa as the primary Hawaiian name for P. nudum and moa nahele as the primary Hawaiian name for P. complanatum.

Moa is also the name for: the red jungle chicken (Gallus gallus), brought to Hawai‘i by early Polynesians; a type of banana fruit; a dart used in a sliding game; a trunkfish; a stone fastened to a rope used as a weapon; and a small gastropod [Pukui & Elbert 1986].

Etymology

The genus name, Psilotum, comes from the Greek word psilos, meaning "naked" or "smooth," alluding to the smooth stems of plants in this genus [Palmer 2003]. Similarly, the species name, nudum, is Latin for "bare, naked, thornless," again, referring to the naked nature of the species' stems [Gledhill 2008].

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