lspichkin

Courtesty of joe shlabotnik on flickr

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, rarely reaching as high as 20 metres by climbing over other plants.

Botany
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.

Pests and Diseases
Roses are subject to several diseases. The most serious is rose rust (Phragmidium mucronatum), a species of rust fungus, which can defoliate the plant. More common, though less debilitating, are rose black spot, caused by the fungus Diplocarpon rosae, which makes circular black spots on the leaves in summer, and powdery mildew, caused by Sphaerotheca pannosa.

Fungal diseases are best solved by a preventative fungicidal spray program rather than by trying to cure an infection after it is visible. After the disease is visible, its spread can be minimized through pruning and use of fungicides although actual infection cannot be reversed. Some rose varieties are considerably less susceptible than others to fungal disease.

The main insect pest affecting roses is the aphid (greenfly), which sucks the sap and weakens the plant. Ladybirds are a predator of aphids and should be encouraged in the rose garden. Spraying with insecticide is often recommended but should be done with care to minimize loss of beneficial insects.

Cultivation
Roses thrive in temperate climates, though certain species and cultivars can flourish in sub-tropical and even tropical climates, especially when grafted onto appropriate rootstock.

There is no single system of classification for garden roses. In general, however, roses are placed in one of the following groups:

* Wild Roses

* Old Garden Roses - In general, Old Garden Roses of European or Mediterranean origin are once-blooming shrubs, with notably fragrant, double-flowered blooms primarily in shades of white, pink and red. The shrubs' foliage tends to be highly disease-resistant, and they generally bloom only on two-year-old canes.

* Modern Garden Roses - Classification of modern roses can be quite confusing because many modern roses have old garden roses in their ancestry and their form varies so much. The classifications tend to be by growth and flowering characteristics, such as "large-flowered shrub", "recurrent, large-flowered shrub", "cluster-flowered", "rambler recurrent", or "ground-cover non-recurrent".

* Landscape Roses - These are a modern classifation of rose developed mainly for mass amenity planting. In the late 20th century, traditional hybrid tea and floribunda rose varieties fell out of favor amid gardeners and landscapers, as they are often labor- and chemical-intensive plants susceptible to myriad pest and disease problems. So-called "landscape" roses have thus been developed to fill the consumer desire for a garden rose that offers color, form and fragrance, but is also low maintenance and easy to care for.

Most landscape roses having the following characteristics:
- Good disease resistance
- Lower growing habit, usually under 60cm
- Repeat flowering
- Disease and pest resistance
- Non suckering, growing on their own roots.


Courtesy of Wikipedia
David Austin English Rose 'Mary Rose' (named for the Mary Rose) in the Albury, New South Wales Botanical Gardens.

More Links

• David Austin Roses
• American Rose Society
• All-America Rose Selections