Cultivation

When cultivated, trees are propagated from fresh seed harvested in March. Bottle trees grow best in well drained, slightly acidic soil, in full sunshine. Suited to temperate subtropical and tropical climates. In the first stages of growth, the Bottle Tree is very slow growing, and the formation of the unique bottle shape is not visible until the tree is about fifteen years old. Mature trees transplant easily, and can withstand intervals of up to three months between digging and replanting without detriment. The Bottle Tree can also withstand temperatures of -10 °C to +50 °C in its natural habitat.

Species

Zonneveld & Duncan (2003) divided Agapanthus into six species (A. africanus, A. campanulatus, A. caulescens, A. coddii, A. inapertus, A. praecox). ^[7] Four additional taxa were recognised by Leighton (1965) as species (A. comptonii, A. dyeri, A. nutans, A. walshii), ^[8] but were given subspecific rank by Zonneveld & Duncan. All species recognized by Leighton or by Zonneveld and Duncan are listed below. A. orientalis is also listed.

• Agapanthus africanus (syn. A. umbellatus; African Lily or African Tulip)
• Agapanthus campanulatus (African bluebell, African Blue lily or Bell Agapanthus)
• Agapanthus caulescens
• Agapanthus coddii (Codd's Agapanthus or Blue Lily)
• Agapanthus comptonii
• Agapanthus dyeri
• Agapanthus inapertus (Drakensberg Agapanthus or Drooping Agapanthus)
• Agapanthus nutans
• Agapanthus orientalis
• Agapanthus praecox (Common Agapanthus, Blue Lily, African Lily, or Lily of the Nile)
• Agapanthus walshii

Description

Agapanthus is a genus of herbaceous perennials that mostly bloom in summer. The leaves are basal and curved, linear, and up to 60 cm (24 in) long. They are arranged in two rows.

The inflorescence is a pseudo-umbel subtended by two large bracts at the apex of a long, erect scape, up to 2 m (6.6 ft) tall. They have funnel-shaped flowers, in hues of blue to purple, shading to white. Some hybrids and cultivars have colors not found in wild plants. The ovary is superior. The style is hollow. Agapanthus does not have the distinctive chemistry of Alliaceae.

Relationships

Four valid botanical names have Agapanthus as their basionym.^[9]

In 1985, Dahlgren, Clifford, and Yeo placed Agapanthus in Alliaceae, close to Tulbaghia.^[10] Their version of Alliaceae differed from any that are recognized today in that it included Agapanthus and in that it included several genera that would later be transferred to Themidaceae.

In 1996, in a phylogenetic analysis of DNA sequences of the gene rbcL, Themidaceae was resurrected and Agapanthus was removed from Alliaceae.^[11] The authors found Agapanthus to be sister to Amaryllidaceae and transferred it to that family. This was not accepted by the Angiosperm Phylogeny Group when they published the APG system in 1998, because the clade consisting of Agapanthus and Amaryllidaceae had only 63% bootstrap support. The APG system recognized the families Agapanthaceae, Alliaceae, and Amaryllidaceae. Agapanthaceae consisted of Agapanthus only, and Dahlgren's idea that it is close to Tulbaghia was rejected. The APG circumscriptions of the latter two families would eventually become known as Alliaceae sensu stricto, and Amaryllidaceae sensu stricto.

When the APG II system was published in 2003, it offered the option of combining Agapanthaceae, Alliaceae sensu stricto, and Amaryllidaceae sensu stricto to form a larger family, Alliaceae sensu lato. When the name Amaryllidaceae was conserved by the ICBN for this larger family, its name was changed from Alliaceae to Amaryllidaceae, but its circumscription remained the same. When APG II was replaced by APG III in 2009, Agapanthaceae was no longer accepted, but was treated as subfamily Agapanthoideae of the larger version of Amaryllidaceae.^[12] Also in 2009, Armen Takhtajan recognized the three smaller families allowed by APG II, instead of combining them as in APG III.^[13]

Molecular phylogenetic analysis of DNA sequences has shown that Agapanthus is sister to a clade consisting of subfamilies Allioideae and Amaryllidoideae of the family Amaryllidaceae (sensu APG III).^[14] These two subfamilies are equivalent to the families Alliaceae sensu stricto, and Amaryllidaceae sensu stricto, respectively.

Cultivation and uses

An agapanthus beginning to bloom

An agapanthus in pre-bloom stage

Agapanthus africanus can be grown within USDA plant hardiness zones 9 to 11. In lower-numbered zones, the bulbs should be placed deeper in the soil and mulched well in the fall. Agapanthus can be propagated by dividing the bulbs or by seeds. The seeds of most varieties are fertile.

Several hundred cultivars and hybrids are cultivated as garden and landscape plants. Several are winter-hardy to USDA Zone 7.

In some regions, one or more species of Agapanthus are invasive plant species. In New Zealand Agapanthus praecox is classed as an "environmental weed"^[15] and calls to have it added to the National Pest Plant Accord have encountered opposition from gardeners.

References

Origin

The origin of P. × hybrida is thought to be by hybridisation between P. axillaris (the large white or night-scented petunia) and P. integrifolia (the violet-flowered petunia). P. axillaris bears night-fragrant, buff-white blossoms with long, thin tubes and somewhat flattened openings. The species was first sent from South America to Paris in 1823. P. integrifolia has a somewhat weedy habit, spreading stems with upright tips, and small lavender to purple flowers. It was discovered in South America by the explorer James Tweedie, after whom the genus Tweedia is named, who sent specimens to the Glasgow Botanical Garden in 1831. Many open-pollinated species are also gaining popularity in the home garden.^[2] A wide range of flower colours, sizes, and plant architectures are available in both the hybrid and open-pollinated species.^[3]

Classification

Some botanists place the plants of the genus Calibrachoa in the genus Petunia.^[3] In botanical classification, tobacco, tomato, potato, and petunia are all in the family Solanaceae.^[4]

Petunias are generally insect pollinated, with the exception of P. exserta, which is a rare, red-flowered, hummingbird-pollinated species. Most petunias are diploid with 14 chromosomes and are interfertile with other petunia species.^[5][6]

The tubular flowers are favoured by some Lepidoptera species, including the Hummingbird hawk moth.^[7] The flowers are eaten by the larvae of the corn earworm, Helicoverpa zea and the cabbage looper, Trichoplusia ni.^[8]

Cultivation

Petunia seeds germinate in 5 to 15 days. Petunias can tolerate relatively harsh conditions and hot climates. They need at least five hours of sunlight every day. They grow well in low humidity, moist soil. Young plants can be grown from seeds. Petunias should be watered once every two to five days. In drier regions, the plants should be watered daily.^[9] Dead petals should be pruned so that the younger branches can flourish. Maximum growth occurs in late spring. Applying fertilizers once a month will help the plant grow quickly. Petunias can be cultivated in hanging baskets.

Categories

Grandiflora

This type of petunia has the largest flowers, up to 4 inches (100 mm) in diameter. Of all the petunias these have the widest variety of forms and colours but are the most likely to be damaged by heavy rain. There are four types of grandiflora and they are classified by their colours: ‘Daddy Series’ (shades of pink and purple), ‘Merlin Blue Morn’ (blue and white), ‘Supercascade Series’ (many colours) and ‘Ultra Series’ (many colours, including bi-colour).^[10]

Hedgiflora (spreading)

Hedgifloras or spreading petunias (sometimes called ground-cover)^[9] are characterised by their low height (usually about six inches), but they have a large spread (about three to four feet). They will cover a large area, provided they have adequate water and fertilisation. ‘Purple Wave’ was the first introduced cultivar of spreading petunia and grows to a height of 4 inches (100 mm). ‘Tidal Wave’ is another spreading type of petunia, but is much taller (between sixteen and twenty-two inches). 'Surfinia' petunias are another type of spreading petunia propagated by cuttings. ‘Opera Supreme’ is a cultivar with large flowers.^[11]

Multiflora

Multifloras are half the size of grandifloras, being 2 inches (51 mm) in diameter. They are not easily damaged in heavy rain and are more sun-tolerant. Multiflora petunia cultivars include: 'Carpet Series "(many colours) and 'Madness Series' (many colours). They spread quickly and are ideal for baskets.^[10]

Milliflora

Millifloras are the smallest of the petunias, being about 1-inch (25 mm) across. These are commonly mixed with other plants in containers, along garden beds and edges. Millifloras are available in 'Fantasy Series' (red, purple, pink) and are the easiest to find. 'Supertunia Mini Series' (blue, pink, lilac, purple and white) are also available in the milliflora category. They tolerate harsh weather better when compared with grandifloras and multifloras.^[10]

Species

Species include P. alpicola, P. altiplana, P. axillaris, P. bajeensis, P. bonjardinensis, P. exserta, P. guarapuavensis, P. helianthemoides, P. humifusa, P. inflata, P. integrifolia, P. interior, P. ledifolia, P. littoralis, P. mantiqueirensis, P. occidentalis, P. parviflora, P. patagonica, P. pubescens, P. reitzii, P. riograndensis, P. saxicola, P. scheideana, P. variabilis, P. villadiana.

Nothospecies: P. × atkinsiana.

Gallery

• 

  Purple petunia

• 

  Pink petunia flower in full bloom

• 

  White petunia

• 

  Basket of petunias

• 

  Multicoloured petunias

• 

  Overflowing petunias

• 

  Yellow shock wave petunias

• 

  Purple petunias

• 

  A field of petunias

• 

  Start of bloom, Blooming, Senescence

• 

  Petunia flowers in Weizmann Institute of Science

• 

  Pink Petunia in Weizmann Institute of Science

• 

  Floral arrangement of petunias in Columbus, Ohio

Botany

Cross-section through a developing rose hip

Exterior view of rose buds

Rose leaflets

The leaves are borne alternately on the stem. In most species they are 5 to 15 centimetres (2.0 to 5.9 in) 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 hybrid garden rose "Amber Flush"

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. There are multiple superior ovaries that develop into achenes.^[4] 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.

Rose-picking in the Rose Valley near the town of Kazanlak, 1870s, engraving by F. Kanitz

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 and slope stabilization. They also have minor medicinal uses.

Ornamental plants

The 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).

Hybrid Tea cultivar 'Mrs. Herbert Stevens'

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.^[5] 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

Bouquet of pink roses

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.^[6]

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, and more recently into eastern Europe. In Bulgaria, Iran and Germany, damask roses (Rosa damascena 'Trigintipetala') are used. In other parts of the world Rosa centifolia is commonly 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.

Geraniol (C₁₀H₁₈O)

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. In France there is much use of 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.

Rosa canina hips

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.^[7]

Culture

Art

Roses are a favored subject in art and therefore used in various artistic disciplines. They appear in portraits, illustrations, on stamps, as ornaments or as architectural elements. The Luxembourg born Belgian artist and botanist Pierre-Joseph Redouté is known for his detailed watercolours of flowers, particularly roses.

Renoir's painting of cabbage roses, Roses in a vase

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

Wild roses are host plants for a number of pests and diseases. Many of these are also shared with other plants, including especially other genera of the Rosaceae.

Cultivated roses are often subject to severe damage from insect, arachnid and fungal pests and diseases. In many cases they cannot be usefully grown without regular treatment to control these problems.

See also

Botany portal Gardening portal

• Rose
  • Rose species
  • Garden roses
    • List of rose cultivars named after people
    • Rose garden
      • Rose trial grounds
    • Rose show
  • Rose cultivars
• rose (color)
• rose (name)

References

Species

Zonneveld & Duncan (2003) divided Agapanthus into six species (A. africanus, A. campanulatus, A. caulescens, A. coddii, A. inapertus, A. praecox). ^[7] Four additional taxa were recognised by Leighton (1965) as species (A. comptonii, A. dyeri, A. nutans, A. walshii), ^[8] but were given subspecific rank by Zonneveld & Duncan. All species recognized by Leighton or by Zonneveld and Duncan are listed below. A. orientalis is also listed.

• Agapanthus africanus (syn. A. umbellatus; African Lily or African Tulip)
• Agapanthus campanulatus (African bluebell, African Blue lily or Bell Agapanthus)
• Agapanthus caulescens
• Agapanthus coddii (Codd's Agapanthus or Blue Lily)
• Agapanthus comptonii
• Agapanthus dyeri
• Agapanthus inapertus (Drakensberg Agapanthus or Drooping Agapanthus)
• Agapanthus nutans
• Agapanthus orientalis
• Agapanthus praecox (Common Agapanthus, Blue Lily, African Lily, or Lily of the Nile)
• Agapanthus walshii

Description

Agapanthus is a genus of herbaceous perennials that mostly bloom in summer. The leaves are basal and curved, linear, and up to 60 cm (24 in) long. They are arranged in two rows.

The inflorescence is a pseudo-umbel subtended by two large bracts at the apex of a long, erect scape, up to 2 m (6.6 ft) tall. They have funnel-shaped flowers, in hues of blue to purple, shading to white. Some hybrids and cultivars have colors not found in wild plants. The ovary is superior. The style is hollow. Agapanthus does not have the distinctive chemistry of Alliaceae.

Relationships

Four valid botanical names have Agapanthus as their basionym.^[9]

In 1985, Dahlgren, Clifford, and Yeo placed Agapanthus in Alliaceae, close to Tulbaghia.^[10] Their version of Alliaceae differed from any that are recognized today in that it included Agapanthus and in that it included several genera that would later be transferred to Themidaceae.

In 1996, in a phylogenetic analysis of DNA sequences of the gene rbcL, Themidaceae was resurrected and Agapanthus was removed from Alliaceae.^[11] The authors found Agapanthus to be sister to Amaryllidaceae and transferred it to that family. This was not accepted by the Angiosperm Phylogeny Group when they published the APG system in 1998, because the clade consisting of Agapanthus and Amaryllidaceae had only 63% bootstrap support. The APG system recognized the families Agapanthaceae, Alliaceae, and Amaryllidaceae. Agapanthaceae consisted of Agapanthus only, and Dahlgren's idea that it is close to Tulbaghia was rejected. The APG circumscriptions of the latter two families would eventually become known as Alliaceae sensu stricto, and Amaryllidaceae sensu stricto.

When the APG II system was published in 2003, it offered the option of combining Agapanthaceae, Alliaceae sensu stricto, and Amaryllidaceae sensu stricto to form a larger family, Alliaceae sensu lato. When the name Amaryllidaceae was conserved by the ICBN for this larger family, its name was changed from Alliaceae to Amaryllidaceae, but its circumscription remained the same. When APG II was replaced by APG III in 2009, Agapanthaceae was no longer accepted, but was treated as subfamily Agapanthoideae of the larger version of Amaryllidaceae.^[12] Also in 2009, Armen Takhtajan recognized the three smaller families allowed by APG II, instead of combining them as in APG III.^[13]

Molecular phylogenetic analysis of DNA sequences has shown that Agapanthus is sister to a clade consisting of subfamilies Allioideae and Amaryllidoideae of the family Amaryllidaceae (sensu APG III).^[14] These two subfamilies are equivalent to the families Alliaceae sensu stricto, and Amaryllidaceae sensu stricto, respectively.

Cultivation and uses

An agapanthus beginning to bloom

An agapanthus in pre-bloom stage

Agapanthus africanus can be grown within USDA plant hardiness zones 9 to 11. In lower-numbered zones, the bulbs should be placed deeper in the soil and mulched well in the fall. Agapanthus can be propagated by dividing the bulbs or by seeds. The seeds of most varieties are fertile.

Several hundred cultivars and hybrids are cultivated as garden and landscape plants. Several are winter-hardy to USDA Zone 7.

In some regions, one or more species of Agapanthus are invasive plant species. In New Zealand Agapanthus praecox is classed as an "environmental weed"^[15] and calls to have it added to the National Pest Plant Accord have encountered opposition from gardeners.

References

Botany

Description

The genus includes annuals, herbaceous plants, subshrubs, and small shrubs. The color of some lavender flowers has come to be called lavender.

The leaves are long and narrow in most species. In other species they are pinnately toothed, or pinnate, sometimes multiple pinnate and dissected. Flowers are borne in whorls, held on spikes rising above the foliage. Flowers may be blue, violet or lilac. The calyx is tubular, with five lobes. The corolla is often asymmetric.^[1]

Nomenclature and taxonomy

History

Historically L. stoechas, L. pedunculata and L. dentata were described in Roman times (Lis-Balchin 2002). From the Middle Ages onwards, the European species were considered two separate groups or genera, Stoechas (LL. stoechas, pedunculata, dentata) and Lavandula (LL. spica, latifolia), until Linnaeus combined them, believing the name lavandula derived from the Latin 'lavare' to wash, referring to the use of infusions of the plants. He only recognised 5 species in the Species Plantarum (1753), L. multifida and L. dentata (Spain) and L. stoechas and L. spica from Southern Europe. L. pedunculata was included within L. stoechas.

By 1790 L. pinnata and L. carnosa were recognised. The latter was subsequently transferred to Anisochilus. By 1826 de Lassaras described 12 species in three sections, and by 1848 eighteen species were known.

One of the first modern major classifications was that of Dorothy Chaytor in 1937 at Kew. The six sections she proposed for 28 species still left many intermediates that could not easily be assigned. Her sections included Stoechas, Spica, Subnudae, Pterostoechas, Chaetostachys and Dentatae. However all the major cultivated and commercial forms resided in the Stoechas and Spica sections. There were four species within Stoechas (Lavandula stoechas, L. dentata, L. viridis and L. pedunculata) while Spica had three (L. officinalis (now L. angustifolia), L. latifolia and L. lanata). She believed that the garden varieties were hybrids between true lavender L. angustifolia and spike lavender (L. latifolia). ^[2]

Current classification

Currently Lavandula is considered to have 3 subgenera (Upson and Andrews 2004), Lavandula, Fabricia and Sabaudia. In addition there are numerous hybrids and cultivars in commercial and horticultural usage. A number of other species within Lamiaceae are closely related (outgroups) including Ocimum gratissimum, Hyptis pectinata, Plectranthus barbatus and Tetradenia fruticosa. ^[3] (they come from Alaska and come in many different shades)

The first major clade corresponds to subgenus Lavendula, and the second Fabricia. The Sabaudia group is less clearly defined. Within the lavendula clade, the subclades correspond to the existing sections, but place Dentatae separately from Stoechas, not within it. Within the Fabricia clade, the subclades correspond to Pterostoechas, Subnudae, and Chaetostachys.

Thus the current classification includes 39 species distributed across 8 sections (the original 6 of Chaytor and the two new sections of Upson and Andrews), in three subgenera (see Table below). However, since lavender cross-pollinates easily, there are countless variations that present difficulties in classification.

Distribution

The native range extends across the Canary Islands and Madeira, North and East Africa, Southern Europe and the Mediterranean, Arabia and India. Because the cultivated forms are planted in gardens worldwide, they are occasionally found growing wild as garden escapes, well beyond their natural range. Commonly such adventitious establishment is apparently harmless at worst, but in some cases Lavandula species have become invasive; for example, in Australia Lavandula stoechas has become a cause for concern; it occurs widely throughout the continent, and has been declared a noxious weed in Victoria since 1920.^[4] It also is regarded as a weed in parts of Spain.^[5]

Growing lavenders

Lavenders flourish best in dry, well-drained, sandy or gravelly soils in full sun.^[6] All types need little or no fertilizer and good air circulation; in areas of high humidity, root rot due to fungus infection can be a problem. Avoid organic mulches; use pea gravel, decomposed granite, or sand instead, as organics can trap moisture around the plants' bases, encouraging root rot.^[7]

Currently Lavandula is considered to have 3 subgenera (Upson and Andrews 2004), Lavandula, Fabricia and Sabaudia. In addition there are numerous hybrids and cultivars in commercial and horticultural usage. A number of other species within Lamiaceae are closely related (outgroups) including Ocimum gratissimum, Hyptis pectinata, Plectranthus barbatus and Tetradenia fruticosa. [3]

Uses

The most common "true" species in cultivation is the common or English lavender Lavandula angustifolia (formerly L. officinalis). A wide range of cultivars can be found. Other commonly grown ornamental species are L. stoechas, (Spanish lavender) L. dentata (French lavender), and L. multifida (Egyptian lavender). Some species such as Lavandula stoechas are not winter hardy in temperate climates - USDA Zones 8-10). ^[8]

The lavandins Lavandula × intermedia are a class of hybrids of L. angustifolia and L. latifolia.^[9] The lavandins are widely cultivated for commercial use, since their flowers tend to be bigger than those of English lavender and the plants tend to be easier to harvest, but lavandin oil is regarded by some to be of a lower quality than that of English lavender, with a perfume less sweet.^[10]

Culinary use

A bee on a lavender flower

Flowers yield abundant nectar from which bees make a high-quality honey. Monofloral honey is produced primarily around the Mediterranean, and is marketed worldwide as a premium product. Flowers can be candied and are sometimes used as cake decorations. Lavender flavors baked goods and desserts (it pairs especially well with chocolate), and is also used to make "lavender sugar".^[11] Lavender flowers are occasionally blended with black, green, or herbal tea, adding a fresh, relaxing scent and flavor.

Though it has many other traditional uses in southern France, lavender is not used in traditional southern French cooking. It does not appear at all in the best-known compendium of Provençal cooking, J.-B. Reboul's Cuisinière Provençale ^[12] In the 1970s, a herb blend called herbes de Provence usually including lavender was invented by spice wholesalers,^[13] and lavender has more recently become popular in cookery.

Lavender lends a floral and slightly sweet flavor to most dishes, and is sometimes paired with sheep's-milk and goat's-milk cheeses. For most cooking applications the dried buds (also referred to as flowers) are used, though some chefs experiment with the leaves as well. Only the buds contain the essential oil of lavender, from which the scent and flavor of lavender are best derived.

In the United States, both lavender syrup and dried lavender buds are used to make lavender scones and marshmallows.

Medical uses

Lavender is used extensively with herbs and aromatherapy. English lavender (Lavandula angustifolia) yields an essential oil with sweet overtones, and can be used in balms, salves, perfumes, cosmetics, and topical applications. Lavandin, Lavandula × intermedia (also known as Dutch lavender), yields a similar essential oil, but with higher levels of terpenes including camphor, which add a sharper overtone to the fragrance. Mexican lavender, Lavandula stoechas, is not used medicinally, but mainly for landscaping.

Essential oil of lavender has antiseptic and anti-inflammatory properties.^{[citation needed]} It was used in hospitals during World War I to disinfect floors and walls. These extracts are also used as fragrances for bath products.

According to folk wisdom, lavender has many uses. Infusions of lavender are believed to soothe insect bites, burns, and headaches. Bunches of lavender repel insects.^{[citation needed]} In pillows, lavender seeds and flowers aid sleep and relaxation.^{[citation needed]} An infusion of flowerheads added to a cup of boiling water soothes and relaxes at bedtime. Lavender oil (or extract of Lavender) heals acne when used diluted 1:10 with water, rosewater, or witch hazel; it also treats skin burns and inflammatory conditions.^{[citation needed]}

A recent clinical study investigated anxiolytic effects and influence on sleep quality. Lavender oil with a high percentage of linalool and linalyl acetate, in the form of capsules, was generally well tolerated. It showed meaningful efficacy in alleviating anxiety and related sleep disturbances.^[14]

Health precautions

These remedies should be used with caution since lavender oil can also be a powerful allergen.

Avoid ingesting lavender during pregnancy and breastfeeding.^[15]

In vitro, lavender oil is cytotoxic. It increases photosensitivity as well. Lavender oil is cytotoxic to human skin cells in vitro (endothelial cells and fibroblasts) at a concentration of 0.25%. Linalool, a component of lavender oil, may be its active component.^[16] Aqueous extracts reduced mitotic index, but induced chromosomal aberrations and mitotic aberrations in comparison with control, significantly. Aqueous extracts induced breaks, stickiness, pole deviations and micronuclei. These effects were related to extract concentrations.^[17]

However, according to a 2005 study "although it was recently reported that lavender oil, and its major constituent linalyl acetate, are toxic to human skin cells in vitro, contact dermatitis to lavender oil appears to occur at only a very low frequency. The relevance of this in vitro toxicity to dermatological application of Lavandula oils remains unclear."^[18]

In terms of phototoxicity, a 2007 investigative report from European researchers stated that, "Lavender oil and sandalwood oil did not induce photohaemolysis in our test system. However, a few reports on photosensitivity reactions due to these substances have been published, e.g. one patient with persistent light reaction and a positive photo-patch test to sandalwood oil."^[19]

Controversy over possible endocrine-disrupting activity

In 2007, a study was published in the New England Journal of Medicine which indicated that studies in human cell lines indicated that both lavender oil and tea tree oil had estrogenic and antiandrogenic activities. They concluded that repeated topical exposure to lavender and tea tree oils probably caused prepubertal gynaecomastia in some boys.^[20] The Aromatherapy Trade Council of the UK has issued a rebuttal.^[21]

The Australian Tea Tree Association, a group that promotes the interests of Australian tea tree oil producers, exporters, and manufacturers issued a letter that questioned the study and called on the New England Journal of Medicine for a retraction (ATTIA).^[22]

The New England Journal of Medicine has so far not replied and has not retracted the study.

Other uses

Lavender products for sale at the San Francisco Farmers Market.

Flower spikes are used for dried flower arrangements. The fragrant, pale purple flowers and flower buds are used in potpourris. Lavender is also used extensively as herbal filler inside sachets used to freshen linens. Dried and sealed in pouches, lavender flowers are placed among stored items of clothing to give a fresh fragrance and to deter moths. Dried lavender flowers have become recently popular for wedding confetti. Lavender is also popular in scented waters and sachets.

History

The ancient Greeks called the lavender herb nardus, after the Syrian city of Naarda. It was also commonly called nard.^[23]

Lavender was one of the holy herbs used in the biblical Temple to prepare the holy essence, and nard is mentioned in the Song of Solomon (4,14)

nard and saffron,^[24]
calamus and cinnamon,
with every kind of incense tree,
with myrrh and aloes,
and all the finest spices.^[25]

During Roman times, flowers were sold for 100 denarii per pound, which was about the same as a month's wages for a farm laborer, or fifty haircuts from the local barber. Lavender was commonly used in Roman baths to scent the water, and it was thought to restore the skin.^{[citation needed]} Its late Latin name was lavandārius, from lavanda (things to be washed), from the verb lavāre (to wash).^[26] When the Roman Empire conquered southern Britain, the Romans introduced lavender.^{[citation needed]} The Greeks discovered early on that lavender if crushed and treated correctly would release a relaxing fume when burned.

Taxonomic table

Gallery

• 

  Lavender flower

• 

  Lavender flowers

• 

  Lavandula stoechas

• 

  Lavender Farm in Oregon

• 

  Lavender farm in Tasmania

• 

  A lavender farm in Hokkaidō.

• 

  Flower of cultivated lavender; Lavandula stoechas or Spanish lavender.

• 

  Hardy and disease resistant; Lavandula Intermedia or Silver Edge lavender.

• 

  Lavender plant.

• 

  A field of Lavender in France

• 

  picture taken on a balcony in Brussels

• 

  A field of lavender in England

• 

  Lavender at sunset

References

Sources

• Chaytor D A. A taxonomic study of the genus Lavandula. 1937
• Lis-Balchin M (ed.). Lavender: The genus Lavandula. Taylor and Francis 2002
• Upson T, Andrews S. The Genus Lavandula. Royal Botanic Gardens, Kew 2004
• United States Department of Agriculture GRIN: Lavandula
• Joan Head: The Lavenders
• Everything Lavender

References

• Missouri Botanical Garden entry
• Plantzafrica description

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This Astereae article is a stub. You can help Wikipedia by expanding it. v d e

Botanical background

The scientific name is derived from the Greek osteon (bone) and Latin spermum (seed). It has been given several common names: African Daisy, South African Daisy, Cape Daisy and Blue-eyed Daisy.

There are about 50 species, native to Africa, 35 species in southern Africa, and southwestern Arabia. They are half-hardy perennials or subshrubs. Therefore they do not survive outdoor wintry conditions, but there is still a wide range of hardiness.

Their alternate (rarely opposite) leaves are green, but some variegated forms exist. The leaf form is lanceolate. The leaf margin is entire, but hardy types are toothed.

The daisy-like flowers consists of disc florets and ray florets, growing solitary at the end of branches or sometimes in inflorescences of terminal corymbose cymes. The disc florets are pseudo-bisexual and come in several colors such as blue, yellow and purple. The hardy types usually show a dark blue center in the disc until the yellow pollen is shed. The ray florets are female and are found diverse colors such as white, cream, pink, purple, mauve to yellow. Some cultivars have "spooned" petals such as "Pink Whirls". Many species flower a second time late summer, stimulated by the cooler night temperatures. Hardy types show profuse flowering in the spring, but they do not get a second flush of flowers.

Most widely sold cultivars are grown as annuals and are mainly hybrids of O. jucundum, O. ecklonis and O. grandiflorum and can be hardy to -2°C (30°F). If hardy, they can be grown as perennials or as shrubs.

Varieties with orange petals and purple centers are recognized as John Chappel variety in recognition of the famous physician.

Culture

Plants prefer a warm and sunny position and rich soil, although they tolerate poor soil, salt or drought well. Modern cultivars flower continuously when watered and fertilised well, and dead-heading is not necessary, because they do not set seed easily. If planted in a container, soil should be prevented from drying out completely. If they do, the plants will go into "sleep mode" and survive the period of drought, but they will abort their flower buds and not easily come back into flower. Moreover, roots are relatively susceptible to rotting if watered too profusely after the dry period.

Species

This section may require cleanup to meet Wikipedia's quality standards. (Consider using more specific cleanup instructions.) Please help improve this section if you can. The talk page may contain suggestions. (May 2008)

• Osteospermum acanthospermum
• Osteospermum amplectens
• Osteospermum attenuatum
• Osteospermum australe
• Osteospermum barberae
• Osteospermum breviradiatum, Lemoenboegoe
• Osteospermum burttianum
• Osteospermum calendulaceum L. f., Stinking Roger (synonym of Oligocarpus calendulaceus)
• Osteospermum caulescens
• Osteospermum clandestinum (synonym of Tripteris clandestina)
• Osteospermum dentatum
• Osteospermum ecklonis (DC.) Norl., Cape Marguerite, Blue-and-white Daisybush
• Osteospermum fruticosum (L.) Norl., Trailing African Daisy, Shrubby Daisybush
• Osteospermum grandidentatum, Yellow Trailing Daisy
• Osteospermum grandiflorum
• Osteospermum hyoseroides
• Osteospermum imbricatum
• Osteospermum jucundum (Phill.) T. Norl., South African Daisy
• Osteospermum microphyllum
• Osteospermum monocephalum (Oliv. & Hiern) Norl.
• Osteospermum muricatum
• Osteospermum oppositifolium (synonym of Tripteris oppositifolia)
• Osteospermum pinnatum
• Osteospermum polygaloides
• Osteospermum potbergense AR Wood & B. Nord
• Osteospermum rigidum
• Osteospermum rotundifolium
• Osteospermum sinuatum (DC.) Norl. (synonym of Tripteris sinuata)
• Osteospermum spinescens
• Osteospermum subulatum DC.
• Osteospermum tomentosum
• Osteospermum triquetrum L. f.
• Osteospermum vaillantii^[2]

A phylogenetic study has revealed that several changes had to be made to this genus:

• Osteospermum section Blaxium belongs in the genus Dimorphotheca
• the subgenus Tripteris had to be separated from Osteospermum
• the genus Oligocarpus has to be separated from Osteospermum
• Osteospermum sanctae-helenae, endemic to St. Helena, belongs to Oligocarpus.

New species are still being discovered, such as O. australe, O. burttianum and O. potbergense.

Osteospermum flowers are popular in the nursery trade. Propagation is mainly carried out by cuttings. Numerous hybrids and cultivars have been grown with a wide range of tropical colors. Yellow cultivars tend to have a yellow center (sometimes off-white).

One of the most popular cultivars is Osteospermum "Pink Whirls", which features purple to lavender-blue "spooned" petals around a blue disk, also known as "Purple Spoon". It is an evergreen subshrub with green, somewhat glossy, lanceolate opposite leaves. It grows to a height of 40 cm. At night or when it is getting colder, the petals close.

Other cultivars include : Osteospermum "Acapulco", O. "African Queen", O. "Apricot", O. "Biera", O. "Big Pink", O. "Bodegas Pink", O. "Buttermilk", O."Chris Brickell", O. "Duet", O."Giles Gilbey", O. "Hopleys", O. "Ice White", O. "Marbella", O. "Nairobi Purple", O. "Passion Mix", O. "Pink", O. "Pink Beauty", O. "Silver Sparkler", O. "Soprano", O. "Starshine", O."Springstar Gemma", O. "Sunkist", O. "White Whirls" and O."Whirlygig".

Image gallery

"Passion Mix" cultivar.   Osteospermum × dimorphotheca "Lemon Symphony" (an annual cultivar).   Osteospermum 'Sunadora Hotspots Marbella', a modern hybrid.   Osteospermum 'Sunadora Hotspots Acapulco', another modern hybrid.   Osteospermum "Pink Whirls", a cultivar.   Pink Whirls"—close-up.   White Spoon Osteospermum.   Osteospermum barberiae.

Notes

References

• Nordenstam, B., and Bremer, Kare (editor). "Tribe Calenduleae" in: Asteraceae: Cladistics and Classification. Portland, Oregon: Timber Press, 1994. ISBN 0-88192-275-7. Pp. 365–376.