Records of more rare, beautiful and interesting species of the HVMCA

The year 2008/9 revealed several rare and interesting species in the ancient oak woodland and marshland on the periphery of the Helford Estuary.

In September 2008, the strange fungus Claviceps purpurea var. spartina or Ergot, so-called because of its fruit/spore body, up to an inch long and resembling the spur on a cockerel’s foot (Fr. ergot = spur), was widepread, growing on the inflorescences or flower spikes of the Common Cord-grass,Spartina anglica. This was observed in the upper Gweek creeks, especially near the ‘pottery’ bridge. Normally this fungus is found growing on other members of the grass family, some of which are our most important food crops such as barley, oats, rye and wheat.

Ergot is deadly poisonous and poisoning by C. purpurea (ergotism) as a result of eating bread using contaminated flour has been recorded since the Middle Ages and before. Outbreaks were so sudden and inexplicable that many myths and superstitions grew up around the affliction which was widely believed to be a form of divine punishment on sinners and was known as the Holy Fire!

The poisoning can take two forms: a) that of a burning sensation in the limbs followed by gangrene due to excessive vasoconstriction of the blood vessels or, b) causing hallucinations, psychotic behaviour and convulsions.

Analysis of ergot extracts revealed a cocktail of chemicals, some of which are related to the mind-altering substance LSD. Another of these chemical, Ergometrin, has been used in pregnant women to enhance uterine contractions and reduce maternal bleeding by constricting uterine blood vessels after childbirth. Yet another, a caffeine and ergotamine product, was used to treat migraine headaches.

Also found in Autumn 2008, in Merthen Wood, was the so-called Scarlet Caterpillar fungus Cordyceps militaris. The bright red-orange, club-shaped fruit/spore body projects 2-5cm out of the ground and what is even more interesting, when carefully dug out of the ground the basal end is seen to be attached to a dead larva or pupa of a butterfly or moth species buried in the soil. The mycelium or ‘feeding threads’ of the fungus have fed upon and replaced the inside of the insect.

Insects

Autumn 2008 also saw the search for the extremely rare weevil (beetle) Anchonidium unguiculare in the leaf litter of Gweek woods. This weevil was first discovered, as new to British fauna from these woods in 1893. A small (2.2 – 3.0mm) and very inactive species, this weevil was only known in Britain from the ancient woodland in the Gweek area and from a very localised area of coastal grassland in South Devon. My searches have revealed the presence also of this red Data Book 2 species in Bonallack, Merthen, Calamansack, Tremayne and Frenchman’s Creek woods, and, more recently, in Devichoys Wood near Stickenbridge, on the road to Truro.

June 2009 revealed a very large population of the Golden-haired or Hornet Longhorn beetle, Leptura aurulenta which nectars at flowers of umbellifers, brambles and broom in Merthen Wood. This impressive Nationally Scarce, Notable A species with its large size and black/ yellow-golden markings, has its main UK concentration here in Cornwall.

Finally in May 2009 whilst, once again, sieving leaf mould for the presence of the rare weevil A. unguiculare in Bonallack Wood, a small hemipteran shield bug Sehirus biguttatus with a black body characterised by two pale spots on the wing-cases was found. The identity of this insect was immediately obvious to me, after all, I had only been looking for this species in Cornwall for the previous 15-20 years! This rare Notable B bug has undergone a major and dramatic decline in Britain due to changes in woodland management. It feeds on seeds of the Common Cow-wheat Melampyrum pratense in warm, sunny situations in ancient oak woodlands. The adults are mostly found on the ground amongst leaf litter beneath the host plants and so are easy to overlook.

This species was favoured in the past by management of woodlands as coppices and now only survives in unmanaged woods such as Bonallack, where the canopy is naturally thin, good light penetration is possible and the host plant survives. The only other Cornish record is from the Victoria County History list (1906).

Dr Paul A Gainey
Naturalist, photographer and biological recorder

Extract from HVMCA newsletter No.39 Autumn 2009