| TAXON: | Cladonia ciliata Stirt. (1888) |
| RECENT SYNONYMS: | Cladonia ciliata var. tenuis (Flörke) Ahti (1993) |
| FAMILY: | Cladoniaceae |
| GROWTH FORM: | Secondary thallus fruticose, heteromerous (podetiate); primary thallus crustose, heteromerous (squamulose) |
| SUBSTRATES: | Mineral soil |
| PHOTOBIONT: | Asterochloris alga |
| REPRODUCTION: | Pycnidia; apothecia rare |
| ASCUS: | If present, elongate-clavate; apex thickened, with K/I+ blue tholus and deep-blue gelatinous outer sheath; 8 spores |
| SPORES: | Conidia curved; ascospores if present ellipsoid |
| NOTABLE FEATURES: | Podetia tall, gracile, ecorticate, mainly dichotomously branching, distinctly suffused purple-brown towards tips; branches mostly downturned in one direction; primary thallus evanescent |
| CHEMICAL TESTS: | Thallus K± dingy yellow, Pd+ orange-red (fumarprotocetraric acid, ±usnic acid) |
| HABITAT: | Acid dunes, grassland and heathland; western woods |
| DISTRIBUTION: | Widespread in Britain but only locally common |
| CONSERVATION STATUS: | Least Concern |
| LICHENICOLOUS FUNGI: | Abrothallus cladoniae, Leucogyrophana lichenicola, Lichenosticta alcicornaria, Niesslia cladoniicola |
| IDENTIFICATION DIFFICULTY: | Green 2: Field identification possible with care |
| CONFUSION SPECIES: | Cladonia portentosa, Cladonia rangiferina |
FIELD NOTES
Cladonia ciliata is one of a baker’s dozen of ‘reindeer lichens’ that can be found in Britain. It’s not the most common of this type of tall, clumping, richly branching Cladonia, but it’s widespread. You might well come across it in acid grassland, heathland or dunes alongside its somewhat more common cousins, C. furcata and C. portentosa.
At first, the various ‘reindeer-lichen’ Cladonia might seem just an inscrutable jumble of branches, especially as they tend to grow nearby or together. But once you know what you’re looking for, the common species can be disentangled. And C. ciliata does have its own distinctive ‘look’.
As so often with Cladonia, that ‘look’ is a combination of characters rather than one diagnostic feature alone. If I suspect I’ve encountered C. ciliata, it’s because I’ve first noticed that the tips of the podetia are suffused purple-brown, and that they bend with a particular ‘nap’ or direction. I then examine the podetia more closely to determine whether they’re ecorticate, and whether they branch mostly dichotomously.
If you observe this combination of features, you can fairly safely conclude that your lichen is C. ciliata. There are other ecorticate ‘reindeer lichens’, most notably the common C. portentosa. Some of them also have a ‘nap’ or direction, such as C. rangiferina. But only C. ciliata is ecorticate, has a ‘nap’, branches mostly dichotomously, and displays a purple-brown colouration at its tips.
Best practice involves corroborating your initial conclusion with spot-tests. C. ciliata tests Pd+ orange-red from fumarprotocetraric acid. It also ‘officially’ tests K-, but don’t be confused by a K+ dingy yellow or brownish yellow reaction, which is again due to fumarprotocetraric acid.
These tests don’t of themselves prove that your lichen is C. ciliata. C. portentosa for example also tests K- and at least sometimes Pd+ orange-red. But they can help build evidence if the combination of morphological features described above is less clear.
In Britain, C. ciliata is typically recorded as one of two varieties by overall colour: the grey-hued C. ciliata var. ciliata that lacks usnic acid, and the yellow-tinged C. ciliata var. tenuis that has it. All the specimens illustrated below are C. ciliata var. tenuis, which seems to be somewhat more common in Britain.
The two varieties of C. ciliata may turn out in fact to be different species, though the research isn’t yet conclusive. But if they are, it will prove useful in future to have a distinct set of records for each variety (note the two BLS numbers above).
LAB NOTES
Cladonia ciliata can normally be identified without microscopy.
SPECIMENS
Cladonia ciliata var. tenuis : England : VC25 East Suffolk : TM0975 : April 2025 : On mineral soil
Cladonia ciliata var. tenuis : England : VC28 West Norfolk : TF7145 : November 2024 : On mineral soil : First record for hectad
Cladonia ciliata var. tenuis : Scotland : VC98 Argyll : NR8393 : August 2024 : On mineral soil
Cladonia ciliata var. tenuis : England : VC25 East Suffolk : TM4770 : May 2024 : On mineral soil
Cladonia ciliata var. tenuis : Scotland : VC101 Kintyre : NR7372 : August 2023 : In soil pocket on siliceous boulder
