A rose is a flowering shrub of the genus Rosa, and the flower of this shrub. There are more than a hundred species of wild roses, all from the northern hemisphere and mostly from temperate regions. The species form a group of generally prickly shrubs or climbers, and sometimes trailing plants, reaching 2–5 metres tall, occasionally reaching as high as 20 metres by climbing over other plants.
The name originates from Latin rosa, borrowed through Oscan from colonial Greek in southern Italy: rhodon (Aeolic form: wrodon), from Aramaic wurrdā, from Assyrian wurtinnu, from Old Iranian *warda (cf. Armenian vard, Avestan warda, Sogdian ward, Parthian wâr).
Rose hips are sometimes eaten, mainly for their vitamin C content. They are usually pressed and filtered to make rose hip syrup, as the fine hairs surrounding the seeds are unpleasant to eat (resembling itching powder). They can also be used to make herbal tea, jam, jelly and marmalade. A rose that has aged or gone rotten may not be particularly fragrant, but the rose's basic chemistry prevents it from producing a pungent odor of any kind. Notably, when balled and mashed together the fragrance of the rose is enhanced. The fragrance of particularly large balls of mashed roses is enhanced even further. Rose hips are also used to produce an oil used in skin products. Rose shrubs are often used by homeowners and landscape architects for home security purposes. The sharp thorns of many rose species deter unauthorized persons from entering private properties, and may prevent break-ins if planted under windows and near drainpipes. The aesthetic characteristics of rose shrubs, in conjunction with their home security qualities, makes them a considerable alternative to artificial fences and walls
The leaves of most species are 5–15 centimetres long, pinnate,
with (3–) 5–9 (–13) leaflets and basal stipules; the leaflets usually
have a serrated margin, and often a few small prickles on the underside
of the stem. The vast majority of roses are deciduous, but a few (particularly in Southeast Asia) are evergreen or nearly so.
The flowers of most species roses have five petals, with the exception of Rosa sericea,
which usually has only four. Each petal is divided into two distinct
lobes and is usually white or pink, though in a few species yellow or
red. Beneath the petals are five sepals (or in the case of some Rosa sericea,
four). These may be long enough to be visible when viewed from above
and appear as green points alternating with the rounded petals. The
ovary is inferior, developing below the petals and sepals.
The aggregate fruit of the rose is a berry-like structure called a rose hip. Rose species that produce open-faced flowers are attractive to pollinating bees and other insects,
thus more apt to produce hips. Many of the domestic cultivars are so
tightly petalled that they do not provide access for pollination. The
hips of most species are red, but a few (e.g. Rosa pimpinellifolia) have dark purple to black hips. Each hip comprises an outer fleshy layer, the hypanthium, which contains 5–160 "seeds" (technically dry single-seeded fruits called achenes) embedded in a matrix of fine, but stiff, hairs. Rose hips of some species, especially the Dog Rose (Rosa canina) and Rugosa Rose (Rosa rugosa), are very rich in vitamin C, among the richest sources of any plant. The hips are eaten by fruit-eating birds such as thrushes and waxwings, which then disperse the seeds in their droppings. Some birds, particularly finches, also eat the seeds.
While the sharp objects along a rose stem are commonly called
"thorns", they are actually prickles — outgrowths of the epidermis (the
outer layer of tissue of the stem). True thorns, as produced by e.g. Citrus or Pyracantha,
are modified stems, which always originate at a node and which have
nodes and internodes along the length of the thorn itself. Rose
prickles are typically sickle-shaped hooks, which aid the rose in
hanging onto other vegetation when growing over it. Some species such
as Rosa rugosa and R. pimpinellifolia have densely
packed straight spines, probably an adaptation to reduce browsing by
animals, but also possibly an adaptation to trap wind-blown sand and so reduce erosion and protect their roots (both of these species grow naturally on coastal sand dunes). Despite the presence of prickles, roses are frequently browsed by deer. A few species of roses only have vestigial prickles that have no points.