The rose genus
Rosa is the only genus on this site that supplies three separate products to a florist, bred in different directions by different people for different reasons. It is also a plant that most people describe incorrectly in two ways before they have finished the sentence.
somewhere between 100 and 200 species, depending on the authority
The northern hemisphere, from the subarctic to the subtropics
Everything in this guide that belongs to Rosa
The distinction is real and it is not pedantry, because the two things grow from different tissue and behave differently in the hand. A thorn is a modified branch, wired into the wood of the stem and supplied from deep inside it, which is why a hawthorn or a blackthorn spine cannot be removed without cutting into the wood.
A rose has prickles. They are outgrowths of the skin of the stem and nothing more, attached only at the surface with no connection to the plumbing underneath. That is why a thumb run firmly down a rose stem takes them off in a strip, cleanly, leaving small pale scars and an undamaged stem. Every florist does this without thinking about it, and it works because of what a prickle is.
It also explains the variety. Prickles are skin deep, so they vary enormously between species and cultivars without affecting anything structural: hooked and flattened for climbing through scrub, straight and needle fine, red and translucent, densely bristled, or nearly absent. Some modern cultivars are effectively smooth, and none of it costs the plant a thing.
The other thing usually described wrongly is what follows the flower. A rose hip looks like a berry and is not one. It is a swollen hollow cup, the same structure the flower was sitting on, which closes over and turns fleshy and red as it ripens.
The actual fruits are inside it. Each hip holds a cluster of small hard seed like objects, and every one of those is a complete individual fruit with a seed in it, so a single hip is a bag containing many fruits rather than one fruit containing many seeds. Cut one across and they are obvious, packed in among a mass of fine stiff hairs.
Those hairs are worth knowing about. They are irritant, they were the original itching powder, and they are the reason anything made from hips has to be strained thoroughly. The same structure appears across this part of the rose family, which is why an apple core sits in the middle of the flesh rather than the flesh growing around a stone.
Rose classification has a hard line through it at 1867. Everything bred before that is an old garden rose and everything after is a modern rose, and the marker is a single French cultivar that combined the repeat flowering of one group with the form and vigor of another. That cross became the hybrid tea, and the hybrid tea became the long straight single headed rose that the whole world now pictures when it hears the word.
What that rose was optimized for was the cut flower trade at industrial scale: a stem that travels, a bloom that holds a tight spiral for a week and a plant that crops continuously. Those are shipping qualities, and breeding hard for them for a century left a flower that is superb at surviving a journey.
The garden rose in a florist's bucket is a deliberate reversal of that. From the 1960s onward breeders crossed the old European roses back onto modern ones to recover the cupped and quartered form and the scent, while keeping the repeat flowering the old ones lacked. The spray rose went a third way again, selected for many small blooms on one stem instead of one large one. Three plants from one genus, and the differences between them are decisions rather than accidents.
Rose oil is priced by the gram. Producing a single kilogram of it takes something on the order of three to four tonnes of petals, which is why it has always been among the most costly materials in perfumery and why almost everything sold as rose scented has never been near a rose.
Two species do nearly all of it, and the growing is concentrated in a handful of valleys in Bulgaria and Turkey and in parts of Iran and Morocco. The petals are picked by hand between roughly dawn and mid morning, because the oil content falls away as the day warms, and they go to the still the same day. A field that is worth harvesting at five in the morning is worth much less by eleven.
What comes out is not one product. Steam distillation gives the true attar, which sets solid in cool weather, and solvent extraction of the same petals gives an absolute with a different and deeper character. Both are made from flowers that would look unremarkable in a bunch, since these are small loose scented roses grown for their chemistry rather than their shape.