From Wikipedia, the free encyclopedia
A
rose is a
perennial plant of the
genus Rosa, within the family
Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp
prickles. Flowers are large and showy, in a number of colours from white through yellows and reds. Most species are native to Asia, with smaller numbers native to Europe, North America, and northwest Africa. Species,
cultivars and
hybrids are all widely grown for their beauty and fragrance. Rose plants range in size from compact, miniature roses, to climbers that can reach 7 meters in height. Species from different parts of the world easily hybridize, which has given rise to the many types of garden roses.
[1]
The name
rose comes from French, itself from Latin,
rosa, which was borrowed from
Oscan, from Greek
ρόδιόν rhodion (
Aeolic υρόδιόν wrodion), from
Old Persian 𐎹𐎢𐎼𐎭𐎡 wurdi "flower" (cf.
Avest.
warda,
Sogdian ward,
Parthian wâr).
[2][3]
Botany
The
leaves are borne alternately on the stem. In most species they 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. Most roses are
deciduous but a few (particularly from South east
Asia) are
evergreen or nearly so.
The
flowers of most species 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. Roses are insect-pollinated in nature.
The
aggregate fruit of the rose is a berry-like structure called a
rose hip. Many of the domestic cultivars do not produce hips, as the flowers 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.
Rose thorns are actually prickles - outgrowths of the epidermis.
While the sharp objects along a rose stem are commonly called "thorns", they are technically
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
Rosa 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 have only vestigial prickles that have no points.
Species
The genus
Rosa is subdivided into four subgenera:
- Hulthemia (formerly Simplicifoliae, meaning "with single leaves") containing one or two species from southwest Asia, R. persica and Rosa berberifolia which are the only roses without compound leaves or stipules.
- Hesperrhodos (from the Greek for "western rose") contains Rosa minutifolia and Rosa stellata, from North America.
- Platyrhodon (from the Greek for "flaky rose", referring to flaky bark) with one species from east Asia, Rosa roxburghii.
- Rosa (the type subgenus) containing all the other roses. This subgenus is subdivided into 11 sections.
- Banksianae - white and yellow flowered roses from China.
- Bracteatae - three species, two from China and one from India.
- Caninae - pink and white flowered species from Asia, Europe and North Africa.
- Carolinae - white, pink, and bright pink flowered species all from North America.
- Chinensis - white, pink, yellow, red and mixed-color roses from China and Burma.
- Gallicanae - pink to crimson and striped flowered roses from western Asia and Europe.
- Gymnocarpae - one species in western North America (Rosa gymnocarpa), others in east Asia.
- Laevigatae - a single white flowered species from China
- Pimpinellifoliae - white, pink, bright yellow, mauve and striped roses from Asia and Europe.
- Rosa (syn. sect. Cinnamomeae) - white, pink, lilac, mulberry and red roses from everywhere but North Africa.
- Synstylae - white, pink, and crimson flowered roses from all areas.
Uses
Roses are best known as ornamental plants grown for their flowers in the garden and sometimes indoors. They have been also used for commercial perfumery and commercial cut flower crops. Some are used as landscape plants, for hedging and for other utilitarian purposes such as game cover. They also have minor medicinal uses.
Ornamental plants
Main article:
Garden rosesThe majority of ornamental roses are hybrids that were bred for their flowers. A few, mostly species roses are grown for attractive or scented foliage (such as
Rosa glauca and
Rosa rubiginosa), ornamental thorns (such as
Rosa sericea) or for their showy fruit (such as
Rosa moyesii).
Ornamental roses have been cultivated for millennia, with the earliest known cultivation known to date from at least 500 BC in
Mediterranean countries,
Persia, and
China.
[4] Many thousands of rose
hybrids and
cultivars have been bred and selected for garden use as flowering plants. Most are
double-flowered with many or all of the
stamens having mutated into additional
petals.
In the early 19th century the
Empress Josephine of France patronized the development of rose breeding at her gardens at
Malmaison. As long ago as 1840 a collection numbering over one thousand different cultivars, varieties and species was possible when a rosarium was planted by
Loddiges nursery for
Abney Park Cemetery, an early Victorian garden cemetery and arboretum in England.
A few species and hybrids are grown for non-floral ornamental use. Among these are those grown for prominent hips, such as the flagon shaped hips of
Rosa moyesii. Sometimes even the thorns can be treated as an attraction or curiosity, such as with
Rosa sericea.
Cut flowers
Roses are a popular crop for both domestic and commercial
cut flowers. Generally they are harvested and cut when in bud, and held in refrigerated conditions until ready for display at their point of sale.
In temperate climates, cut roses are often grown in
glasshouses, and in warmer countries they may also be grown under cover in order to ensure that the flowers are not damaged by weather and that pests and disease control can be carried out effectively. Significant quantities are grown in some tropical countries, and these are shipped by air to markets across the world.
[5]
Perfume
Rose perfumes are made from
attar of roses or rose oil, which is a mixture of volatile
essential oils obtained by steam distilling the crushed petals of roses. An associated product is
rose water which is used for cooking, cosmetics, medicine and in religious practices. The production technique originated in
Persia then spread through
Arabia and
India, but nowadays about 70% to 80% of production is in the
Rose Valley near
Kazanluk in
Bulgaria, with some production in
Qamsar in
Iran and
Germany.
[citation needed] The
Kaaba in
Mecca is annually washed by the Iranian
rose water from Qamsar
[citation needed]. In Bulgaria, Iran and Germany, damask roses (
Rosa damascena 'Trigintipetala') are used. In the French rose oil industry
Rosa centifolia is used. The oil is transparent pale yellow or yellow-grey in colour. 'Rose Absolute' is solvent-extracted with hexane and produces a darker oil, dark yellow to orange in colour. The weight of oil extracted is about one three-thousandth to one six-thousandth of the weight of the flowers; for example, about two thousand flowers are required to produce one gram of oil.
The main constituents of attar of roses are the fragrant
alcohols geraniol and l-
citronellol; and rose camphor, an odourless
paraffin. β-
Damascenone is also a significant contributor to the scent.
Rose water, made as a byproduct of rose oil production, is widely used in Asian and Middle Eastern cuisine. The French are known for their
rose syrup, most commonly made from an extract of rose petals. In the United States, this French rose syrup is used to make rose
scones and
marshmallows.
Rose hips
The
rose hip, the fruit of some species, is used as a minor source of Vitamin C.
Rose hips are occasionally made into
jam,
jelly, and
marmalade, or are brewed for tea, primarily for their high
vitamin C content. They are also pressed and filtered to make rose hip syrup. Rose hips are also used to produce
Rose hip seed oil, which is used in skin products and some makeup products.
Medicine
The fruits of many species have significant levels of vitamins and have been used as a food supplement (see previous section). Many roses have been used in herbal and folk medicines.
Rosa chinensis has long been used in Chinese traditional medicine. This and other species have been used for stomach problems, and are being investigated for controlling cancer growth.
[6]
Culture
Art
Roses are often portrayed by
artists. The Luxembourg born
Belgian artist
Pierre-Joseph Redouté produced some of the most detailed paintings of roses.
Henri Fantin-Latour was also a prolific painter of still life, particularly flowers including roses. The Rose 'Fantin-Latour' was named after the artist.
Other impressionists including
Claude Monet,
Paul Cézanne and
Pierre-Auguste Renoir have paintings of roses among their works.
Symbolism
The long cultural history of the rose has led to it being used often as a symbol.
Pests and diseases
Roses are subject to several
diseases. The main fungal diseases affecting the leaves are
rose black spot (
Diplocarpon rosae),
rose rust (
Phragmidium mucronatum),
rose powdery mildew (
Sphaerotheca pannosa) and rose
downy mildew (
Peronospora sparsa). Stems can be affected by several
canker diseases, the most commonly seen of which is stem canker (
Leptosphaeria coniothyrium). Diseases of the root zone include
honey fungus (
Armillaria spp.),
verticillium wilt, and various species of
phytophthora.
Fungal leaf diseases affecting roses are best prevented by choosing to grow cultivars and species known to be less susceptible to attack, and by using a preventative
fungicidal spray program (rather than by trying to cure an infection after it emerges on the plant). After disease is visible, spread can be minimized through pruning and the use of fungicides, although the actual infection cannot be reversed. Stem cankers are best treated by pruning out infection as soon as it is noticed. Root diseases are not usually possible to treat, once infection has occurred; the most practical line of defence is to ensure that growing conditions maximise plant health and thereby prevent infection. Phytophthora species are waterborne and therefore improving drainage and reducing waterlogging can help reduce infection.
The main pest affecting roses is the
aphid (greenfly), which sucks the sap and weakens the plant. (
Ladybugs are a predator of aphids and should be encouraged in the rose garden.) In areas where they are endemic
Japanese beetles (
Popillia japonica) take a heavy toll on rose flowers and foliage; rose blooms can also be destroyed by infestations of
thrips (
Thysanoptera spp). Roses are also used as food plants by the
larvae of some
Lepidoptera (
butterfly and
moth) species; see
list of Lepidoptera that feed on roses. The spraying with insecticide of roses is often recommended but should be done with care to minimize the loss of beneficial insects.
See also
References
External links
