Finding the real Nephrolepis cordifolia ‘Duffii’

One of the common Nephrolepis cultivars on the market for a long time has been Nephrolepis cordifolia ‘Duffii’. Sometimes referred to as the Lemon Button Fern, it is supposedly a variation of N. cordifolia and has been available for much longer than the famous Boston Fern, N. exaltata. While ‘Duffii’ was introduced in 1878, N. exaltata was circulating in the trade from around 1894. ‘Duffii’ is still a well-known variety today (Indoor Ferns, Boy Altman, 1998) but its appearance has changed dramatically since it was first introduced. This short article explores the history of ‘Duffii’ and what makes this species have such a unique history.

In the nineteenth century, N. cordifolia ‘Duffii’ was first recorded in 1878 by T. Moore, who described it as a new plant in The Gardeners’ Chronicle (1878, p. 622). This plant was initially found by one of the staff members of the Duke of York’s Island at the Botanical

Garden of Sydney (Figure 1). It was noted that this plant had the same leaf form as Athyrium filix-femina ‘Frizelliae’ due to its ‘narrow-fronded and sometimes multifid’ frond. This causes the full frond to have a drooping effect (Figure 2). Additionally, the orbiculate pinna has a forked tip. This type of Nephrolepis is smaller than most at around 60 cm high. At that time, it also didn’t show any tubers or spores, which

led to doubt whether this was indeed an abnormal form N. cordifolia (syn. N. tuberosa). These features made ‘Duffii’ a relatively unique plant.

From its introduction, and during the first part of the twentieth century, many growers produced and sold ‘Duffii’. C. V. Morton reports that ‘Duffii’ may have appeared in the wild as an escapee (’Observations on Cultivated Fern. V. The Species and Forms of Nephrolepis’, American Fern Journal 48:1, 1958, pp. 18–27). There are also some herbarium specimens described as N. tuberosa, a synonym of N. cordifolia, or N. cordata, which is likely a spelling mistake.

Later in the twentieth century, a short note came in the American Fern Journal. This

1962 article reports someone finding a ‘Duffii’ with spores (Rolla Tryon, ‘A Note on

Nephrolepis cordifolia cv. Duffii’, 52, pp. 152–5). This is the first and only record I found of this plant producing spores. The fertile plant was found in Paramaribo, Surinam. There was then discussion as to the original mother of ‘Duffii’ as there are a few discrepancies in appearance with N. cordifolia. No further research has happened to go deeper into the truth behind the origins of ‘Duffii’.

While the current ‘Duffii’ on the market no longer has a forked or cristate tip, it also shows less orbiculate pinnae and more of a mix of the original mother species pinnae with only some orbiculate pinnae (Figure 3 & 4). Up until the mid 1990s, I have found

images and descriptions of the forked tip and fully orbiculate pinnae (Altman, 1998). Where did it go wrong? Is the one on the market now a new variety using an old name?

I hope later to publish more about finding the original ‘Duffii’. I am currently selecting ‘Duffii’ plants I see in garden centres that have forked pinnae and I am beginning some research. Hopefully, this will result in the original form going back on the market

and cause the other mislabelled varieties to have a change of name.

MIGUEL FERNANDEZ VOORTMAN

Miguel is a Dutch horticulture graduate who is currently working for Henk Braam, one of the biggest companies in the world specialising in the mass-production of fern sporelings for the horticulture trade. He has had a long association with the Hortus Botanicus in Leiden and has worked there on a voluntary basis since his early teens. He is particularly interested in ferns and works alongside Harry Roskam in maintaining and expanding their large hardy fern collection. He is a regular attendee at IATFG meetings and has contributed to a previous BPS newsletter.