Tectaria zeilanica, The ‘Oakleaf Fern’

When I first saw Tectaria zeilanica I wasn’t at all sure that it was even a fern. I was in Udawattakele forest in Kandy in Sri Lanka, and had found this patch of small (5 cm) hairy plants with oak-leaf like leaves. I took some photos (Figure 1) and, when back in the hotel, I set about trying to identify this strange plant. This wasn’t as easy as it sounds, as there is no readily available illustrated guide to the ferns of Sri Lanka. So, I fell back on R. H. Beddome’s Ferns of British India (1892), with line illustrations, and Monica Shaffer-Fehre’s unillustrated Flora of Ceylon, Volume XV (2006). From the Flora, I determined that this was a fern that Beddome had named as Gymnopteris quercifolia. Referring to his 1892 book, I found a line drawing originally created for Beddome’s The Ferns of Southern India (1863) by the Tamil artist Govindoo (Figure 2). This showed the fertile frond to be much larger and more slender than the infertile fronds that I had seen. Subsequently, I went back to the forest and found a fertile frond from which I was able to take some spores on a paper handkerchief.

Back in the UK, I sowed these spores in plastic containers and had prothalli within three months. Sporophytes then developed quickly, and I had plants 2 cm high thirteen months after sowing. These grew rapidly over the next three months (Figure 3). At thirty months after sowing, these plants were producing flag-like fertile fronds of their own (Figure 4), from which I was able to collect spores and grow another generation. It is not a difficult fern to maintain, so long as you can keep it in quite a bright place at around 20 ºC and ~80% RH. It is happy in a 50:50 mixture of potting compost and bark and needs to be damp but not waterlogged. It can suffer infestation with aphids, which can be difficult to see and treat as the fronds are so flat against the compost surface. I have found Pyrethrum powder, delivered via a puffer under the plant, to be effective.

For a plant so small, Tectaria zeilanica has had its fair share of synonyms, twelve in all, the most common of which is Quercifilix zeilanica. Indeed, spores have been offered under this name in the BPS Spore Exchange as recently as 2018, and may be available in the upcoming 2022 spore distribution.

Tectaria zeilanica is an interesting and attractive plant and, with its ease of

culture, could be more widely grown (Figure 5).

PETER BLAKE

Peter became interested in tropical ferns whilst making regular trips to India in the 1990’s and 2000’s. He retired from the NHS in 2012 and was able to develop his interest in growing tropical ferns from spores. He now lives in Norwich where he can provide much more space for their culture. He maintains a particular interest in the ferns of South India and Sri Lanka.