Flour is the powder you bake with: "Sift the flour into the bowl." A flower is the blossom on a plant: "She picked a flower from the hedge." They are pronounced identically, so the only thing keeping them apart in writing is the spelling.
The core difference
One is food, the other grows. Flour is grain — usually wheat — milled to a powder. A flower is the reproductive part of a plant, the bit with petals. There is no overlap in meaning at all, only in sound.
Using flour
Flour is a mass noun, so it takes no plural in ordinary use, though bakers speak of flours when comparing types:
- The recipe calls for 300g of plain flour.
- Dust the board with flour before you roll the pastry.
It also works as a verb meaning to coat with flour: "flour the tin", "floured hands".
Using flower
- The wisteria flowers twice a year if you prune it properly.
- He turned up with a bunch of flowers and no explanation.
Flower is also a verb meaning to bloom, and by extension to develop fully: "her confidence flowered at the new school." Flour has no such figurative life.
The memory trick
Flour contains our — think of the phrase "our daily bread". Bread is made from flour, and flour is the one with our inside it. Flower contains low, and flowers grow from low down in the soil. Either hook is enough; most people only need the first.
The connection people find surprising
The two spellings come from a single word. Flour was originally written flower, in the sense of the flower of the meal — the finest part of the ground wheat, the pick of it. English kept the same sense of "finest example" in phrases like "the flower of English youth". The spellings separated over time to keep the two meanings apart, which is why they still sound the same.
Where mistakes happen
Autocorrect is no help here, since both are real words, and the error tends to appear in exactly the places you least want it: recipe cards, packaging, café blackboards. "Flower tortillas" and "self-raising flower" are perennial menu typos.
Watch the compounds too. It is a flour mill, cornflour and wholemeal flour; but a flowerbed, flowerpot, cauliflower and sunflower. Cauliflower is the one that catches people out — despite ending in the baking word's sound, it is spelt with flower, because the edible head is a mass of undeveloped flower buds.
Frequently Asked Questions
Is it "self-raising flour" or "self-raising flower"?
Flour. Anything you bake with is flour. Self-raising flour is flour with a raising agent already mixed in.
Why is cauliflower spelt with "flower"?
Because the white head is made up of tightly packed flower buds, not because of any link to baking. The same goes for the plant name generally.
Do flour and flower sound different at all?
No, they are homophones in standard British and American English, both pronounced like "flou-er". Some speakers compress flower to one syllable, but the two words still match.