Herb
The flower everything else is compared to, and still not simple.
These are associations the community holds, not settled fact — the more a reading is shared, the bolder it sits.
Roses have been cultivated for so long, and hybridised so thoroughly, that the plant in most gardens is a human artefact. The ones that matter for craft and perfumery are older: the damask and the apothecary's rose, grown for scent and for petals rather than for the shape of the bloom, and still harvested by hand at dawn in Bulgaria and Turkey because the oil content falls as the day warms.
Its symbolism is so dense it is almost unusable. Venus and Aphrodite; the Virgin; the rosary; sub rosa, a rose hung over a table to bind everyone under it to secrecy; the wars of English dynasties fought under two of them. Practice inherits the lot and mostly uses rose for love, grief, self-regard and the heart — the four being, in most people's experience, closely related.
Rosehips, the fruit, were gathered by British schoolchildren in the Second World War for syrup when citrus stopped arriving, and that is one of the few things in this entry that is straightforwardly documented and not a matter of interpretation.
Readings practitioners have offered, ordered by how many recognise them. Take what serves, leave the rest.
Carried forward
Nicholas Culpeper, The Complete Herbal (1653)
Culpeper divides the roses up by planet — red under Jupiter, damask under Venus, white under the Moon — and then, without warning or explanation, assigns the Provence rose to the King of France. It is the single funniest line in the Herbal.
Carried forward
European convention, classical onward
A rose suspended over a table put everything said beneath it under an obligation of silence — the sense preserved in the phrase sub rosa. Ceilings in council chambers were sometimes carved with one, which made the rule architectural.
Credit what you carry. Much of this comes from living traditions, and some of it from traditions that are closed — held by particular peoples and not offered for general use. Where you know whose practice a reading came from, name them; where you don't, say that too.