"Nick Maclaren" wrote in a message:

I stand corrected, and a quick check confirms that. Apparently the one
that I thought was a sphagnum is Rhytidiadelphus squarrosus, and it is
not closely related. Anyway, from a gardening viewpoint, it can be used
interchangeably!
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I'm glad that's been cleared up! The moss I have growing in my garden IS
very similar to sphagnum but on a much smaller scale, it works for air
layering and covering the surface of the compost of all my potted up
carnivorous plants.

MCT