(modifié de Coste, Flore de la France 1937) :
Plante vivace, printanière, grêle ; tiges de deux sortes, paraissant en même temps, les fertiles de 15-40 cm, blanchâtres ou rougeâtres, simples ou à courts rameaux verticillés, se développant après la fructification
Écologie : (répartition d'après la flore) Bois et pâturages humides, dans les montagnes de l'Est, du Centre, du Midi, dans le Nord, Normandie, Bretagne.
Répartition hors de France : Europe ; Sibérie, Groenland, Amérique boréale.
(modified from Butcher, British Flora 1961):
NOTE: the French text is more complete and up-to-date
A rather tall and slender plant with erect, twice-branched stems 23-50 cm high. Stem of two kinds, fertile and sterile; the fertile at first brown, but becoming green and branched after sporulation; all smooth with dense whorls of very fine, drooping, secondary branches which are again branched; in cross-section showing 8-12 blunt ribs, an inner ring of tissue and outside, 8-12 tangentially oblongate lacunae, alternate with the ribs, and a rather large central space.
Ecology UK: (distribution according to flora) It occurs in damp, shady places on acid soils, mostly in N. Britain and rarely in the drier parts.
France:
Distribution outside France: ?
Fleurs : aucune
Formation des spores, France : Avril-juin
Flowers: none
Spore formation UK: Mid April-late May
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