are female stinging nettles rarer than male?
Firstly you are correct in that stinging nettles are dioecious – that is they have separate male and female flowers. As far as I am aware, they also have separate male and female plants. The latin name for the stinging nettle is Urtica dioica which indicates its dioecios habit. Stinging nettles reproduce both by vegetative reproduction and by sexual reproduction. In order to produce seeds, you need both male and female plants. The fact that you say that locally there is a predoninance of male plants, would suggest that a few male plants grew from seed in a location that was amenable to vegetative reproduction (high phosphate soils) and these have spread to colonise a larger area. Male plants can continue to spread locally by vegetative reproduction, but to spread to potential new sits will require pollination from a male to female plant.
