Moonwort - an unusual fern

MOONWORT: AN UNUSUAL FERN G. D. HEATHCOTE

Moonwort, Botrychium lunaria (L.) Sw.? is common on part of Lakenheath Warren. This unusual fern is easily recognized. It has a small perennial rootstock with Single stems surrounded at the base by a few brown scales.

The stems grow from about 3 to 8 in. (about 10cm) and bear Single fronds with fan-shaped segments. These are not rolled up spirally like most ferns.

There are branched, yellowish-green terminal spikes with sessile, globular spore cases, all turned to one side.

The plants favour dry, sandy soils. Adder's Tongue, Ophioglossum vulg tum L., like Moonwort belongs to the Ophioglossaceae and occurs in Suffolk, but it favours much heavier, damper soils. The distribution map prepared by Martin Sanford of the Suffolk Biological Records Centre shows that Moonwort has mainly been reported from the north-west and north-east corners of the county. The isolated records from other parts of Suffolk are undated and the SBRC would welcome up-to-date reports from these areas.

Moonwort may no longer be growing there.* Botrychium lunaria • = post 1980 • = pre 1980 = undated record

* Botanically the two parts of the overground structure in these primative ferns may be looked upon as the fertile branches of a dichotomously (two equal branches) branching system. The segments (pinnae) of the sterile branch in Botrychium are then each equal to a modified fertile branch bearing spore cases. In Ophioglossum neith half of the dichotomy is divided into segments. P.J.W. Botanical Editor.

Trans. Suffolk Nat. Soc. 23

Marg R u t t e r f o r d pointed many Moonwort plants out to me on L a k e n h e a t h W a r r e n in early J u n e 1986. Most of them were then severely grazed, and he suggested that this might have been by pheasants. Rabbits used to keep the turf very short there, but they are now few in n u m b e r . Self-sown pines, most about 8 in. (20cm) high, are n u m e r o u s where the M o o n w o r t is growing, but they are not grazed. Mr. R u t t e r f o r d has observed that Moonwort plants are not grazed where they grow within some rabbit-proof enclosures which have been erected on the site for scientific purposes. This suggests that the rabbits were responsible for the grazing damage. H o w e v e r , it could be that pheasants are unwilling to settle and feed in the confined space of the enclosures, f r o m which take-off would be difficult.

Marg R u t t e r f o r d c o m m e n t s on the changes taking place on the Breckland in an article on page 38.

Dr. G . D . H e a t h c o t e , 2, St. Mary's Square, Bury St. E d m u n d s

Trans. Suffolk Nat. Soc. 23