You would say "I gave my mother a single flower". A bouquet implies more than just a lot of flowers. It usually means that they have been arranged and wrapped, with a ribbon round them, ready to present to someone. At the end of an opera performance someone will present the female singers with bouquets. But if I am walking in the countryside and I pick some wild flowers and give them to my wife, I would call them "a bunch of flowers" rather than a bouquet. In England we would never say "a stalk of flower".

Yeah, I've never heard anyone say a 'stalk of flower' here either, though I'm not particularly in the business of handling flowers. You could say 'a flower,' 'flowers,' 'two flowers,' 'three flowers,' 'a couple flowers,' 'a few flowers,' 'a bunch of flowers,' etc.

在英语里一个词有好多的用法，就像你说的bouquet就是一束， a flower ,two flowers ,three flowers [一朵，两朵，三朵] a bunch of flowers也有'束,堆'的意思

it means one and only love.i hope it works.

A stalk of flower. If more than one, you can say " 2 stalk of flowers" or "3 stalk of flowers" and so on.