Stewart Robert Hinsley" schreef
example: n.o. Aristolochiaceae

It's new to me as well. In the absence of any context, I'd take a guess
that it might be "natural order".
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Stewart Robert Hinsley

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I probably would not have thought of that, but it looks like a good guess to
me. Must be something like a century since this was used in botany?
PvR