Ferns from Spores

MANILA, Philippines - All plicataforms (wavy, including lasagna-forms), furcataforms (forking forms), filiforms and serrataforms may all be propagated through spores. Some fasciated forms and irregular multilobatum forms are suspected to be caused by phytoplasma and do not propagate through spores.

Production of ferns through spores takes time and patience. From spore sowing to production of marketable young plants takes around 2 years on the average. 

Spore collection

Spores can be harvested from healthy mother plants as soon as the sori are ripe. The best stage to harvest is when the spores had just started to shed. This may be done with the help of a jeweler’s loop or a hand lens. 

Old fronds normally had shed their spores and are generally useless. Residual spores coming from old fronds are usually contaminated with moss, algae and wild fern spores. 

Fronds or frond sections with spores are wrapped in clean sheet of paper or placed in paper envelopes. Plastic bags should not be used because they trap moisture and will result in moldy spores. The fronds may be placed in a cool, dry room to shed the spores. Air-conditioned room is ideal for this purpose. Always write down the name of the fern and the date of collection. Dry spores of commercial varieties of ferns may be kept for several months.

Species with green spores like Osmunda, Todea and Platycerium walichii have short viability and must be sowed as soon as they are collected.

Spores must be separated from foliage debris before sowing because the plant tissues will grow moldy in culture complicating the production. This maybe achieved by shifting the spores through cloth or through rubber foam.

Spore sowing

Sanitized spores may be sprinkled on moist media. 

There are many types of culture media used for ferns. Commercial spore germinating media may include: sphagmum moss, Asplenium & Platycerium roots, coconut husk chunks, cocopeat, peatmoss, wood chips, tree barks, river sand, soil, old florist foam, red bricks, terra cotta, hollow blocks and boiled jute sack. Anything that can hold some amount of moisture may be used.

All media used in fern spore culture should be sterilized or at least pasteurized with boiling water. Microwavable food keepers are very convenient to use for this purpose. Media that release tannins should be washed before spore-sowing.

After sowing, a light spray of distilled water or deionized water helps rehydrate the spores and make them stick to the media. The sown spore may then be placed in clear plastic bag to maintain a 100% relative humidity. The culture may then be placed in a well lighted (but no direct sunlight) location.

Spores normally germinate after 2 weeks. Green specks may be observed on the surface of the media. These small specks of green cells will eventually grow into heart-shaped tissues called prothallium or prothallus. The prothallium carries the sex cells of ferns.

Prothallus

Mature fern prothalli need a film of water to effect fertilization. A spray of distilled water on mature prothalli during midnoon will result in plantlets after 2 months.

These young plants may be fished out of the box and planted separately when they are big enough to be handled.

Fertilizers in form of nutrient solutions (e.g. Knudson C, Murashige & Skoog, Knop’s solution or Hoagland’s solution) may be used to hasten growth of both prothalli and fern plantlets. 

Commercial fern growers always keep cultivating the prothalli. Technically, the prothallus can be propagated indefinitely. 

Pests and diseases

Fern spore culture is generally in a closed system and is generally pest free if media is sanitized properly. Some of the more common problems encountered in production include: Springtail infestation, mold infection and algae infestation.

Springtails or Carambolas infesting the moist media may be drowned with dish washing liquid. The light surfactant solution may be poured directly into the growing box and solution is decanted after 10 minutes of soaking. The culture is then washed 3 times with clean water. The treatment may need to be repeated as the new batch of springtails hatch after 2 weeks.

Fungal infections may be treated with non-metallic fungicides like Chlorothalonil, Benomyl and Carbendazim.

Algal infestation may be controlled by spray of quaternary ammonium chloride solution or treated with Chlorothalonil.                                                                                                                                                                                                           

Conservation

Nature has equipped ferns to produce billions of spores per plant. There is a very good reason for this: Out of a billion spores, only a few gets to survive and live until maturity in nature. Next time we look at a fern in the wild, we have to think that it is a survivor out of a billion siblings. It deserves more respect than P15 to P25 we pay the gatherer/trader. 

Considering the microclimate change caused by deforestation, and other man-made physical changes to the environment, it won’t be long until these natural beauties are lost. Stripping the forest of these plants for commercial purpose will hasten their extinction.

We can still enjoy the beauty of these ferns if they are propagated en masse through spore culture. There is no logical reason allowing the wild-gathered plants to be exported. Propagation nurseries should be encouraged to grow ferns.