American Fern Society

Collecting Spores for the AFS Exchange

The Spore Exchange welcomes spore donations from members and non-members.  Donations that add new species or update existing species are preferred.  If you think a fern is too common to donate, it might be just what a researcher or someone in another area is looking for.  When collecting spores, please try to collect enough to make three or more packets (approximately 15 cubic millimeters of cleaned spores, minimum).  Generally, a hand-sized area of fertile frond will yield enough spores.

An in-depth PDF presentation on collecting spores is available here. Or, follow the guideline below to avoid some common problems with donated spores such as unripe or over-ripe spores, contamination, incorrect identification, and leaking of spores in transit. 

1.  If possible, take some digital photographs of the fern you are collecting spores from.  Try to include an ordinary object in at least one picture for size reference.  Links to donor-supplied pictures are included in the online list, which helps when selecting ferns and aids in confirming the species/variant identification.  If you do not know the botanical name of the fern or if you are unsure, please send pictures of the plant, both sides of the fronds and close-ups of the fertile fronds.  Sending portions of the dried fronds is also helpful.  The pictures and/or fronds should allow identification at least to the genus level for listing on the exchange.

2.     Collect fertile fronds or portions of fertile fronds with ripe sori (spore bearing patches).  Ripe sori contain sporangia (tiny capsules) that are fully developed but have not yet released their spores.  Unripe sori are generally green or somewhat colorless while over-ripe sori have spent sporangia which look like dull fuzz.  If in doubt, collect portions at various stages of development.  Also, it is better to error toward over-ripe fronds than under-ripe ones because good spores are more likely found among spent sporangia than among unripe sporangia.  Please try to collect a full fertile frond or at least a hand-sized area. Pictured below are unripe, ripe, and over-ripe fertile pinnae of Polystichum tsus-simense.

3.     If the source fern is in a location where it may have received wind-blown spores from other species, or if its fronds are dirty, then thoroughly rinse the cut fronds in a strong stream of cool water and shake off the excess.

4.     Place the collected fronds in a thin white paper envelope - a business envelope will do - and allow it to dry at room temperature for a few days.  Another method is to sandwich the fronds between sheets of smooth white paper held down with a weight.  You can reduce the drying time to an hour or two by scraping the sori off the frond into the envelope or onto a sheet of paper, making sure the scrapings are spread out.  Since the spores are thrown one or two inches from the sporangia during the drying process, close the envelope or provide baffles to contain the spores.

 5.     After the fronds have shriveled and the sporangia have shed their spores, there will be a dusty mixture of spores and chaff (spent sporangia, dried indusia, scales, etc.).  Brush off or tap any remaining material from the fronds before discarding.  Remove most of the chaff from the spores by holding the paper at a slight angle and tapping it so that the chaff bounces forward while the spores stay behind.  Don’t worry if some chaff remains.  If your attempt to clean the spores does not work or you are unsure if there are any spores, go ahead and send all the released or scraped material. All donations will be cleaned using a fine metal sieve when processed for the spore bank.

6.     Seal the spores of each donation in a folded paper or aluminum foil packet.  If paper is used, it should be thin and smooth so the resulting packet has tight folds and lays flat.  Waxed paper should be avoided because it has been shown to decrease spore longevity.  Please do not put the spores directly in a plastic bag and do not use tape to provide a seal.  Spores and chaff tend to statically cling to plastic and adhere en masse to tape residue.  If unsure of the packet seal, consider enclosing it in a small sealed bag. 

7.    Label each packet, or the bag containing the packet, with the botanical name, collection month and year, and location if it was collected in the wild.  Any additional information would be helpful such as habitat, elevation, soil type, hardiness zone, etc.

8.    If the packets are thin, tape them to a sheet of paper using clear (preferably removable) tape and mail in an ordinary business envelope.  Otherwise, send the packets in bulk using a padded shipping envelope.

9.     For information on mailing spores to the exchange, please email spores.afs@comcast.net.  Please include pictures (or better yet, links to the pictures) in your email.

Banner image (Cibotium glaucum) by Tom Ranker.