Cladonia peziziformis

Description

(Adapted from Chambers, 2003)

Photo: Alan Orange

C.peziziformis forms cushions of loosely aggregated, small, rounded-auriculate, greyish-green squamules. It could be confused with the juvenile squamules of a wide range of other heathland Cladonia species but these tend to be more variously marginally incised (sometimes with sorediate or granular-edges), sometimes brownish, erect or decumbent, and less organised. When fresh in the field its squamules can have something of the look of a diminutive grey Omphalina hudsoniana. When fertile it is unmistakeable. It most closely resembles C.cariosa but that species occurs on dry and free-draining, sandy ground, on calcareous substrates, and often on metal-polluted soils. The podetia of C.cariosa are taller ((0.5-) l-2(-2.5)cm), more strongly lacerated and have branched corymbose clusters of dark brown apothecia. In C.peziziformis the podetia are shorter (to ca. lcm) with a single turban-like, paler brown apothecium, or weakly branched with l-2(-3) terminal apothecia.

Drawings: Alan Orange

C.peziziformis is Pd+red, K- (or murky brown); C.cariosa is pd- or +weak yellow, K+y (atranorin). Squamules of both species can have large, sessile, dark brown-black, barrel-like pycnidia, preceding the formation of podetia.

Habitats

C.peziziformis is a terricolous lichen of open, shallow peaty or sandy ground in oceanic lowland and submontane heaths (Orange 1996; Purvis et al. 1992). The vast majority of records are from heathland within a short distance of the coast and the species displays a pronounced 'L-shaped' southerly and westerly distribution in Britain, mirrored by certain Atlantic pteridophytes, such as Dryopteris aemula and Hymenophyllum tunbrigense. The species is intolerant of phanerogamic competitors and appears to have a requirement for bare ground exposed during heath fires. It is possible that the trophic conditions provided by plant ash nutrients released in the aftermath of burns play some role in its ecology and life history and perhaps trigger its appearance from a spore or conidial bank in the soil, though no experimental work has been carried out to investigate this. Nothing is known of its long-range dispersal capabilities. Whether or not disturbance by fire is a prerequisite is also unknown, but recent finds here and in Europe have all been associated with burnt ground. Where C.peziziformis is found the ground typically has a thin peat covering with a significant sandy or mineral fraction. Some sites are associated with igneous geology and nutrient balance appears to be a key factor in the ecology of the species. In this respect it appears to have ecological similarities with Placynthiella oligotropha but occupies more or less constantly humid, cooler and much less xeric niches.

Distribution

N. & S. America, Asia, Macaronesia, W. Europe and Western British Isles. Very rare and probably ephemeral at most sites. In Wales, recorded from 5 locations post-1980.

Records from Wales

Records from Wales (some older and poorly-localised records have been ommitted):

Location	Grid Reference	Last Rec'd	Recorder	SSSI
Anglesey: South Stack	SH208819	2007	S.P. Chambers	Yes
Caernarfon:Mynydd Garngwch	SH374425	2002	S.P. Chambers	?
Pembs: Dowrog Common	SM770269	1989	A.O. Orange	Yes

Hectad Distribution in Wales/NBN Gateway Map

(Be aware that the data on the Gateway may be incomplete and the maps should not therefore be relied upon as a full representation of the distribution of this species. Note that the maps coverage includes some parts of England. Also, without a registered account on the Gateway your access to datasets may be limited)

Threats & Status

Sterile thalli could be overlooked, though the specialised habitat and UKBAP-raised profile means it has attracted increased awareness and it is high on any lichenologist's 'wish list' when working coastal heath. Consequently it is unlikely to be seriously under-recorded.

References

Chambers, S.P. (2003). Site Dossiers for the UK BAP lichens Biatoridium monasteriense, Cladonia peziziformis, Graphina pauciloculata and Schismatomma graphidioides. CCW Contract Science Report No. 586