Well, I'd have said very dissimilar! Spiranthes has the typical orchid shaped flower (like a Cymbidium in miniature), totally unlike the individual flowers on this, and as the name suggests, the flowers run down the stem in a very striking spiral. One of the striking things on the image is the stamens, and orchids in general don't have stamens - they put the pollen in little packages on the upper part of the flower.
I hadn't realised there were Spiranthes in any colour than white (the UK and Europe ones are white), but this page has a picture of a pink flowered species, and shows what I mean by the striking spiral. It also shows the orchid-ness of the flower very clearly.
Terrestrial orchids - Royal Botanic Gardens & Domain Trust - Sydney, Australia
Liriope looks superficially similar *including things like the coloured stem), but none of the pictures I've seen have the flowers as open as that, and I don't know the plant well enough.
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