[305] Rosa chinensis and Other Garden Roses

[305] Rosa Varieties, Rose

Introduction

I was going to use Rosa chinensis, the Chinese Rose, as a species of Rose originating in China that is one of the origins of modern garden Roses. But roses have been cultivated for so long that the thousands of varieties and cultivars are generally not identified to named species. They are probably all hybrids, grafted on to rootstock from Rosa canina or other hybrids. I will look at all garden roses today – apart from [304] Rosa canina and Rosa rugosa considered yesterday. It will be relatively short with about fifty pictures of rose flowers.

Taxonomy

Kingdom – Plants

Division – Vascular Plants

Class – Angiosperms (Flowering Plants)

Order – Rosales

Family – Rosaceae

Genus – Rosa

There are thousands of varieties and cultivars coming from historical hybrids of uncertain origins.

Roses are grafted on to rootstock, which is of only a few types. These are mostly hybrids based on Rosa canina.

Names

The following notes about classifying and naming types of plants below the species level include some generalizations and simplifications.

The International Code of Nomenclature for Algae, Fungi, and Plants defines naming conventions used in plant Taxonomy. I try to keep to the right naming conventions and normally give genus and species identification.

In the world of horticulture, the word variety is used loosely and usually corresponds to the formal term Cultivar. A cultivar is a formally identified type of plant, bred specifically and sometimes marketed under a legally protected name. It is produced by crossing many other varieties. There are thousands of cultivars of roses and most of them are from hybrids rather than specific species. They have another system of conventions, identified in the International Code of Nomenclature for Cultivated Plants.

Cultivars are named to the species level by the rules for plant identification, with the addition of a cultivar epithet – enclosed in single quotes, fully capitalized and not italicized. So, the familiar Granny Smith apple is actually Malus domestica ‘Granny Smith’. Often, especially with roses, the species epithet is left out (for a hybrid) and the common name can be used instead of the scientific name as Rose ‘Duchess of Cornwall’ for Rosa ‘Duchess of Cornwall.’

There are about 35 000 cultivars and hybrids of roses including thousands named after real or fictional people and many hundreds named after places.

History

Roses have been cultivated as ornamental plants since 500 BC or earlier in China and around the Mediterranean. The development of the many cultivars available today started around the Nineteenth Century.

Roses are still very popular in gardens and parks. The production of roses and development of new varieties are both major industries. Wikipedia lists about a hundred people worldwide who are famous for their work in developing new types of rose.

Description

Species of roses are erect shrubs that can use their prickles to climb up over other plants. Most species of Rosa started much like the Dog Rose with five petals. About 150 species come from Eurasia and North America. Flowers are various shades of yellow, white, pink, lilac and red.

Extensive selective cultivation has led to a wide variety of rose cultivars. They can be classified by their types with some taking the form of small trees or shrubs or climbers. Most have larger flowers with many layers of petals. Extra petals can develop instead of stamens leaving flowers that cannot develop fruits. In any case the tightly packed petals often prevent pollination by insects so they do not normally produce rose hips.

Flowers of cultivated roses come in almost all colours.

Cultivation

New varieties can come from complex cross-pollination of other varieties or can arise from a single sport – a chance genetic variation in a single plant that may only be possible to reproduce vegetatively. (We have seen this in [142] Copper Beech and [104] Saffron. The Bramley apple is another classic example.)

I won’t go into details but roses are often propagated by grafting. All horticultural roses are grafted on to a rootstock, often but not always Rosa canina.

Habitat and use

Roses are grown as garden plants and sold as cut flowers. A few species are cultivated specifically but must horticultural roses are cultivars developed from hybrids.

Perfumes are made from Rose oil and rose water is used in cooking, cosmetics, medicine and in some religious practices.

Other Notes

I am sure you can find many examples in literature and popular culture.

[304] Rosa canina, Wild Rose

[304] Rosa canina, Wild Rose

Rosa rugosa, Japanese Rose

Introduction

Rosa canina, the Wild Rose, is a bushy deciduous shrub with open pink flowers, a widespread wildflower in Britain.

Rosa rugosa, the Japanese Rose, is a more compact bush with somewhat larger, redder flowers, widely cultivated in Britain in gardens and parks.

Both species have stems covered in thorns. (Botanists call them prickles, but to most people they are thorns.)

There are many other species of Rosa, called Roses, that we will meet tomorrow.

Rosa canina is also known as the Dog Rose. As a garden plant, Rosa rugosa is more usually called by its scientific name.

[Rugosa is also an order of horn corals, all now extinct.]

Many other unrelated plants are called roses, usually from the similarity of their flowers. We have already met [181] Rose of Sharon and [277] Primrose.

Taxonomy

Kingdom – Plants

Division – Vascular Plants

Class – Angiosperms (Flowering Plants)

Order – Rosales

Family – Rosaceae

Genus – Rosa

Scientific Name – Rosa canina, Rosa rugosa

See the next post for Rosa species, hybrids, varieties and cultivars.

Name

Rose comes via the Latin rosa from Greek rhodon, perhaps from Old Persian roots. It has become a word associated with a light pink colour.

The English dog rose comes from the Classical Latin rosa canina, coming from Ancient Greek. In ancient times it was used to treat the bite of mad dogs, perhaps because the hooked prickles resembled the dog’s canine teeth.

The Latin rugosus means wrinkled, from the leaf shape.

Wild Rose

Rosa canina is a deciduous bushy shrub. It is not really a climbing species but can scramble upwards with the help of thorns along its stems. Leaves, strictly speaking leaflets of a pinnate leaf, are usually serrated.

Flowers are open, almost flat, with five petals, usually light pink but can be from white to a deeper pink. Fruits, initially green, mature to a familiar bright orange or red rose hip (or rosehip.)

The Dog Rose is rarely used as a cultivated garden rose but all cultivated roses are grafted on to rootstock which is generally a variety of Rosa canina.

The genetics of Rosa species in the Canina section is unusual. Only seven of its chromosomes are paired. The others pass down singly via the female egg cells but not in the pollen.  

Rosa Rugosa

I have included this species because its appearance is much closer to the Wild Rose than to the more ornate varieties that have been developed from other Rosa species (coming tomorrow.) Actually, most species have very simple flowers but we never see them in their native, uncultivated forms.

In the wild Rosa rugosa forms dense thickets by developing new plants from its roots. The prickly stems have densely packed prickles (unlike the curved ones for the Rosa canina) and leaves are similar to Rosa canina but with a fine corrugated surface that gives it the name rugose.

Flowers are open and flat like the Wild Rose but larger, generally dark red and with many stamens. The fruit is a similar rose hip but larger, sometimes looking like a cherry tomato. It starts green and turns a bright red.

It is a widely cultivated species and most cultivated varieties retain the simple form of a wild rose. They are suitable for planting in long expanses to fill rose beds, sometimes acting as an effective hedge.

Habitat and use

Rosa canina is native to all of Europe and neighbouring Asia and Africa. Rosa rugosa is native to Japan, Korea and eastern China,

Rose hips, which are high in Vitamin C, are edible raw and can be made into herbal teas, jams, jellies or other culinary products. Rosa canina and Rosa Rugosa are both used in rose hip production.

Other Notes

The rose widely used in heraldry is a simple dog rose, predating the modern garden roses that we will see tomorrow.

What we now call the War of the Roses, was an invention of Henry VII when it ended and the name was rarely used until the Nineteenth Century. The so-called red Rose of Lancaster had barely existed in 1485 and was more usually a gold rose. Henry had fought under the banner of the Welsh Dragon and Henry VI had used the badge of an antelope. Richard III used a boar for his banner. The idea of the War of the Roses enabled Henry to create the Tudor Rose as his emblem, combining the red and white roses as a symbol of unity.

The Red Rose and White Rose are now used to represent the counties of Lancashire and Yorkshire – although the Hose of Lancaster and House of York had no real geographic connections to their respective counties.

The heraldic rose resembled either Rosa canina or a wild European species much like Rosa canina.

See also

More about roses in general will come tomorrow.

[217] Macrosiphum rosae, Rose Aphid and Other Aphids

[217] Macrosiphum rosae, Rose Aphid and Other Aphids

Introduction

Macrosiphum rosae, the Rose Aphid, is just one example of thousands of species of aphids (sometimes called greenfly or blackfly or whitefly) that are normally just considered as unwanted garden pests.

Taxonomy

Kingdom – Animals

Phylum – Arthropods

Class – Insects

Order- Hemiptera

Suborder – Sternorrhyncha

Infraorder – Aphidomorpha (Aphids and a few others)

Superfamily – Aphidoidea (Aphididae and some extinct families)

Family – Aphididae (Aphids)

Subfamily – Aphidinae

Tribe – Macrosiphini

Genus – Macrosiphum

Scientific Name – Macrosiphum rosae

See text for other members of Aphididae

Name

Aphides (singular aphis) is New Latin, invented by Linnaeus, of uncertain origin. It may come from Ancient Greek apheides meaning unsparing or lavishly borrowed – from their voracity and speed of reproduction. The name of the family comes from the genus Aphis.

They are generally just called aphids informally. The ending -idae is standard for families and sometimes Aphidae is used erroneously for Aphididae.

Macrosiphum is from Greek macro-siphon, meaning large-tube. Many aphid genera have -siphum or -siphon in their names, derived from their cornicles. The genus Macrosiphum does have some of the largest aphid species.

Aphids

The family Aphididae comes within the order of true bugs, Hemiptera and its species are hemimetabolous. There are several thousand species of aphids, generally soft-bodied and pear-shaped. Most have a pair of tubes on their abdomens called cornicles used to excrete alarm pheromones when attacked.

Aphids are generally green but can be red, brown, black or almost colourless. The same species may have different coloured forms.

They feed on plant sap and excrete honeydew, which is used as a food by ants and bees. Many types are actively farmed by ants for their honeydew.

As for many taxa, classification is not agreed, with up to dozen subfamilies being recognized.

They usually have both wingless (apterous) and winged (alate) forms in a complex life cycle. Generally flightless females may give birth parthogenetically (without sex) to live female nymphs, which may already be pregnant. They mature rapidly and breed profusely – with up to thirty or forty generations in a year. These are all effectively clones. Winged females may develop later in the season and a phase of sexual reproduction may occur later with insects often overwintering as eggs. (In greenhouse conditions generations of wingless forms may persist for years.)

Most species feed on one type of plant only; some alternate between two types; and some are more general in their food sources.

Because they are so destructive to crops, they are sometimes subject to biological control Many of their natural enemies are insects, particularly ladybirds.

Macrosiphum rosae

The Rose Aphid primarily feeds on [303-4] Roses, particularly the growing tips and buds. In late summer when the flowers emerge, some winged forms move to other rosebushes or other host plants such as [170] Holly, [117] Teasel and others. In the autumn winged males are produced and eggs are laid on rosebushes, where they overwinter.

They vary from green to pink or red-brown.

Other Notes

You are very lucky if you have a garden and don’t see aphids. Even the tribe Macrosiphini has about three hundred genera so identification to species level is not easy.

They may be very specific about their choice of host plant but I don’t think it works in reverse. Even if Rose aphids are only found on Roses, that doesn’t mean that every aphid found on a rosebush is a Rose Aphid! I make no claims about my identifications but I think the ones above are Macrosiphum rosae.

See also

Here are some other aphids on other plants.

You will, of course, notice [086] Seven-spotted Ladybird in the last picture feeding on aphids. The header picture features [169] Harlequin Ladybird.