There must be a Latin name for “plant-like” that could have been used. Maybe “anomalous herbiform entity”. But, I’m poor at crosswords.
Not a meteorologist, but from all I understand it means lens-shaped, and to me that immediately gives a strong clue as to how they form since lenses have focal points and can, to some degree, have shapes expressed as formulae about some origin. Which to me is suggestive of the relation to the mountains around which they form.