What Are Fronds For?

Are you fern friendly?

Most kama'aina are familiar with the native ferns for which we have uses. Palapalai (Microlepia strigosa), sacred to Laka the hula deity, shows up in great profusion especially at Merrie Monarch hula festival time, and hapu'u (Cibotium spp.) lends itself nicely as a living, shaded substrate for growing orchids, for example. But did you know there literally hundreds of native species of ferns and fern allies in Hawaii? Nearly 70 percent of them grow nowhere else in the entire world.

Many folks mistake the Australian tree fern for hapu’u, however it’s an aggressive invasive species that unfortunately gained popularity in local landscaping because of its robustness. It’s this characteristic that allows it to outcompete indigenous and endemic ferns and makes it threat to native forests. If you have it growing in your yard, the best idea is to prune it with a shovel – that is, get rid of it pronto. Be sure you dispose of it by composting it well and don’t let the spores disperse.

This past weekend the Volcano Art Center sponsored Tim Tunison’s workshop in fern identification, and once more he had us plant geeks scrambling for our ID keys and hand lenses, peering at spores, indusia, hairs, scales, pinnae, stipes and other clues to discover the names of some common, uncommon, and even rare species of ferns in the Volcano area. Identifying ferns is fun but sometimes can be a confounding experience for beginners because of the tiny, sometimes microscopic features and occasionally confusing variations!

If you’re someone who likes challenges and has a healthy amount of crazy gardener optimism, try growing ferns from spores. Here’s what you need:

• humid growth chamber
• sterile media
• ripe spores

Tunison recommended these steps for Fern Propagation:

1. Collect ripe spores. Look at the back of the frond for ripe spores which are usually dark brown, but some may be black, red, or yellow.
2. Cut fertile frond and place spore-side down on some white paper, 8 1/2 by 11 inches. Place another sheet on top and press by putting some heavy books on top. Or place inside a book. After a few days, some dust – the spores – will appear. Wait a couple of weeks to harvest all the spores.
3. Prepare sterile media. You can use peat pellets, Sunshine mix, sand, porous brick or a block of florist’s Oasis.
4. Put the spores on top of the media. Try tapping the paper a little to distribute a thin layer of spores over the moistened media. (Yep, it’s not as easy as it sounds. Don’t sneeze.)
5. Place media in growth chamber. If you’re using peat pellets, for example, you could place them inside a clear plastic container with a snap-on lid, such as the ones they sell hydroponic lettuce in, or plastic “clamshells.” Sterilize with a 10% chlorine bleach solution and rinse well before using. Keep media very moist but not waterlogged. This needs a cool environment and no direct sunlight.

In about six months you might see the first baby ferns, which look like flat bits of leaf. Wait a little more until they are developing tiny fronds about the size of a pea, and then transplant. For a more detailed explanation, a good book to consult is Growing Hawai'i’s Native Plants by Kerin Lilleeng-Rosenberger.

Some inspiration: Check out the narrow fronds of this endemic kolokolo fern (Grammitis tenella) hanging off the trunk of a native loulu palm (Pritchardia beccariana). Note that there's also some filmy ferns and a small 'ala 'ala wainui (Peperomia sp.) seedling in the 'ohana, too.

Good luck!