Most keys make much of the respective lengths of the pendent and spreading branches to differentiate the three segregates of Sphagnum recurvum agg. However, this character (and the capitulum shape) does not always work well, especially where plants are growing in sub-optimal habitat or at the edge of range and in borderline specimens it’s helpful to be aware of other, more reliable differences.
S. flexuosum has stem leaves that look broadly similar to those of S. angustifolium, roughly triangular in shape with rounded, plane (or slightly hooded) apices. However, S. flexuosum has leaves longer than wide, with an obviously fringed apex; stem leaves of S. angustifolium are as wide as long and scarcely fringed or entire. S. fallax has quite different stem leaves, more triangular, with a short acute tip and inrolled margins and so is usually easily identified.
Another useful difference is colour. Of the three species, S. flexuosum is the only one that is always green and never has pink or brown pigment at the branch bases.Read the Field Guide account