Chapter 2

American Plants Ratings for Hardiness

The American (USDA) system based on average annual temperature extremes gives 26 ratings ranging from the very hardy plants (category 0a: able to survive down to -54ºC) up to very tender plants (category 12b: able to survive down to +13ºC). A British Isles map showing the appropriate distribution for plants with stated USDA temperature-hardiness ratings was often used by gardeners to plant sensibly, by avoiding the danger of serious frost damage.

However, when considering this USDA system of plant listings as applied to the British Isles, one important factor needs to be remembered. The North Atlantic Drift (Gulf Stream) is a sea current that passes northwards from tropical seas and passes to the west of the British Isles mainland.

The climate of the British Isles is consequently much milder than other countries occupying similar latitudes. Indeed, there is no country at this latitude (50 to 60 degrees north) that has such warm winters. But, in spite of this relative mildness, perennial plants still have many months of winter darkness. This prolonged darkness can seriously reduce growth and survival of perennials, particularly those in the USDA category 10 (species that can survive a temperature down to -1ºC) and category 9 (down to a temperature of -7ºC). To compensate for this prolonged-darkness effect, a suggested strategy is that gardeners choose a plant species from a more hardy category. Thus in a category 9 location as seen on a hardiness map, a more hardy category 8 species such as Mexican orange (Choisya ternata that cansurvive to -12°C) could be chosen instead of a less hardy category 9 plant such as bay laurel (Laurus nobilis that can only survive -7°C). The category 8 species thus has a better chance of survival.

More on Plant Hunters

Ghiselin de Busbecq (1522–1592)

was a Flemish diplomat to the Austrian court who introduced tulips, hyacinths and anemones to Europe from the near-east in the mid fifteen hundreds. This introduction occurred over a hundred years before the ‘Dutch tulip hysteria’ that saw many new Tulipa species being bought in Holland for large sums of money.

John Parkinson (1567–1650)

was a noted botanist and gardener. He lived first in Yorkshire, but at 14 years of age moved to London to follow a successful career as an apothecary (herbalist). At the age of 50, he became apothecary to James I. He later became botanist to Charles I. His 1,700 page Theatre of Plants in 1640 describes almost 4,000 plant species, a real stimulus to plant hunting at the time. Parkinson actively searched for new species of plants using contacts in other countries. He was able to support an expedition to Spain and North Africa in 1607 led by William Boel. At least seven new plant species are thought to have been introduced to England by him, including the ‘great double yellow Spanish daffodil’. His extensive garden near present-day Covent Garden was walled and is recorded as growing about five hundred plant types.

Parkinson died in London in 1650.The genus of leguminous tree Parkinsonia. paradisi from central America is named after him.

John Tradescant the Elder (1570–1638)

was a notable gardener and plant collector from East Anglia who worked for the Earl of Salisbury at Hatfield House, Hertfordshire before becoming involved in garden design for Edward Lord Wotton and later for the Duke of Buckingham. Following a visit to Holland around 1610 to obtain fruit trees, he then visited northern Russia (1618), North Africa, Eastern Mediterranean (1620) and France. He was appointed in 1630 to the position of ‘Keeper of his Majesty’s gardens, vines and silkworms’ in Surrey. Part of his large house in Lambeth was developed into a museum of overseas curiosities (‘the Ark’) and his garden containing introduced plants from many parts of the world was well known as a centre for distribution of exotic plant material to other growers in the area. His surname was used in naming the American genus of monocotyledon Tradescantia.

George Clifford III (1685–1760)

was born in 1685 in Amsterdam; his father was a banker. George was a very successful man, becoming a director of the Dutch East India Company. His large estate near Haarlem in Holland with formal gardens and greenhouses were planted with species from many parts of the world. Linnaeus, the noted taxonomist, was employed in 1736 to catalogue his many plant specimens.

Peter Collinson (1694–1768)

was born in London. Early in his life he developed an interest in botany, using his father’s international business contacts to obtain seeds from many parts of the world. This led him to market these seeds nationally as a business. He established a well-known garden in Mill Hill, London.

John Clayton (1694–1773)

was born in England, but moved to Virginia, in North America (near Chesapeake Bay) with his family in1715. His many botanical specimens were identified largely by the Dutch botanist Jan Frederik Gronovius (and also Linnaeus and George Clifford). The North American flower (Claytonia viginica) was named after him.

John Bartram (1699–1777)

was born in Darby, Pennsylvania, USA into a farming family. He was self-taught in botany and later made contact with European gardeners interested in North American plants who led him to adopt the Linnaean naming system (see page 000). His love for travelling and collecting plants enabled him to develop a successful horticultural business.

He began to explore the eastern American colonies for novel plants. In 1743, at the age of 44, he went north to the regions around Lake Ontario; in 1765 to east Florida and later to the Ohio River. Most of his seed and plant material were sent to Europe. He received in return many useful botanical books in addition to financial payment. In 1765, after much support by Peter Collinson and Benjamin Franklin in England, Bartram received a pension of £50 per year from George III as the King’s Botanist for North America. Following this, Bartram’s seeds and plants went to the royal collection at Kew Gardens and to the Oxford and Edinburgh botanic gardens.

Bartram was not much involved with plant naming (leaving that to European botanists). He is best remembered for the discovery and distribution of many North American flowering trees and shrubs. These include Kalmia, Rhododendron and Magnolia species, Dionaea muscipulia (Venus flytrap), Calico flower (Aristolochia elegans) and the discovery of Franklinia alatamaha (the Franklin tree). He is particularly remembered from the genera of mosses Bartramia. His name also occurs in the species Amelanchier bartramiana (North American serviceberry), and perhaps surprisingly Commersonia bartramia, the subtropical tree from Australia and South-East Asia. He died in 1777 in Philadelphia.

Daniel Solander (1733–1782)

was born in the most northerly part of Sweden. He became a friend of Linnaeus, the noted taxonomist (see page 000). After university, he travelled to the British Isles, largely to encourage the use of the Linnean system of nomenclature. From 1763, he was a key participant in the cataloguing of the British Museum natural history collections and in the following year was elected Fellow of the Royal Society. In 1768, he joined Captain Cook’s famous voyage to the southern hemisphere, collecting many plant species with Joseph Banks. His plant-naming skills were especially useful during a two-month delay for ship-repair in the north of Australia, contributing in a major way towards Banks’s ‘Florilegium’ (see page 000). In 1772, Solander visited Iceland and several Scottish islands together with Joseph Banks. He died in 1782 of a stroke (aged 49) at Banks’s home in London. Nothofagus solandri is named after him.

Alexander von Humboldt (1769–1859) was born in Berlin, the son of a major in the Prussian army. Even when young, he combined a love for travel with natural sciences, and knew Georg Forster, who had been on Captain Cook’s second voyage. After a tour of Europe, and a time as an inspector of mines, Humboldt was keen to travel outside Europe. From 1799 to 1804, he travelled with Aimé Bonpland around northern South America and the Caribbean. His later travels in Russia in 1811 and 1818 provided a few new species. Some of the plants he collected were Lilium humboldtii (Humboldt’s lily), Phragmipedium humboldtii (an orchid), Quercus humboldtii (Andean oak), Annona humboldtii (custard apple), Utricularia humboldtii (bladderwort) and Geranium humboldtii.

George Bentham (1800–1884) was born near Plymouth in 1800, but spent his childhood in Russia and France, his father being a naval architect. As a young man in the south of France, he began a life’s interest in plant collecting. By the age of 29, he was established in England, and already Secretary to the Horticultural Society (a society that increasingly was willing to support plant-hunting expeditions). Around this time, he gave his collection of more than 100,000 dried plant specimens to Kew. His Handbook of the British Flora (1858) brought identification of plants within the understanding of the average man and woman. Flora Hongkongensis and Flora Australiensis followed in 1861 and 1870 respectively. He served as president of the Linnean Society of London from 1861 to 1874. A 21-year partnership between Bentham and Sir Joseph Hooker led, in 1883, to the publication of the massive ‘-Genera Plantarum, a summary of the known plants of the world at that time. This book used the Bentham–Hooker classification system by which plant families could be systematically placed alongside each other, and be grouped into higher units of classification (see also page 000). Much of his retirement was spent at Kew identifying plant species. Although collecting was largely a feature of Bentham’s earlier years, this experience was to be crucial in giving insights as he and Hooker looked to survey the classification of the whole plant kingdom. He died in 1884.

Richard Spruce (1817–1893)

was born in north Yorkshire, the son of a teacher. As a boy, he had a fascination for plant collecting and identification. By the age of 28, he was collecting plants in the Pyrenees, but his major life experience was the 15 years he spent in tropical South America from 1849 to 1864.

His first stop was the port of Para, north-east Brazil. He travelled up the Amazon, spending almost two years exploring the major Tapajoz and Negros tributaries. The Vaupes branch of the Negros reaching into Colombia had tree species in the families Tiliaceae, Bombaceae, Lecythideae and Rubiaceae, and he was most impressed by the beautiful flowers of Erisma (Vochysiaceae).

In 1857, he spent two years further up the Amazon around the town of Tarapo; visits to hilly areas displayed genera known in the British Isles such as Ranunculus, Rubus and Stellaria. Further up the Amazon in the Ecuadorian Andes, during his three year visit to the area, he was recruited by the Indian government to collect a large number of seeds and young plants of the medicinal plant, Cinchona succirubra in theRubiaceae, for cultivation in Sikkim and Nilgiri hills of Iindia. These plants were used for extracting the anti-malarial drug quinine.

In 1864, Spruce’s health broke down and he returned to England, living in his native county Yorkshire for a further 25 years as an invalid until 1893.

Benedict Roezl (1823–1885)

was born in Prague. He is remembered as the most prolific collector of orchid species ever (over 800 species from North, Central, and South America). Miltoniopsis roezlii, Pescatorea roezlii and Selenipedium roezlii are named after him.

Ferdinand von Mueller (1825–1896)

was an Australian plant hunter. He was born in Rostock, Germany. After his first job as a pharmacist, he studied botany and obtained a doctorate on the flora of Schleswig Holstein. He moved to South Australia in 1847 with his two sisters. Six years later, he was appointed Government Botanist for Victoria. He explored the country’s alpine areas and then the Northern Territory for new plants. In 1857, he was appointed Director of the Royal Botanic Gardens in Melbourne.

This energetic botanist was involved in the collection and naming of over 800 species. He encouraged several expeditions around Australia and Antarctica. He helped in the introduction of many Australian plants such as blue gum (Eucalyptus globulus) and Western tea-myrtle (Melaleuca nesophila) to the British Isles. Mueller died in Melbourne in 1896.

James Adams (1839–1906)

was born in Ireland and moved to New Zealand in 1870. He collected many plant specimens over a 30-year period with Thomas Cheeseman. Celmisia adamsii (Asteraceae) and Elytranthe adamsii (Loranthaceae) are named after him.

Frank Kingdon-Ward (1885–1958)

was born in Withington, Lancashire. He was the son of a professor of Botany in Cambridge. After obtaining a natural sciences degree, he took up a teaching position in Shanghai in 1907 for three years. Subsequently, in 1910, he joined an unsuccessful party travelling across central and western China. But in 1911, he finally entered the plant hunting scene in the south-west Chinese province of Yunnan, where he collected Saxifraga wardii, Gentiana wardii and several species of the poppy Mecanopsis (and on a later visit Rhododendron wardii). After a few years’ active service in the First World War, he began, in 1924, his most notable expedition to the Tibetan (eastern) side of the Himalayas. His party found notable species such as Lilium wardii, Mecanopsis betonicifolia, Cotoneaster conspicuus, Rhododendron auritum, R. exasperatum and R. venater. He returned to Sikkim-Tibet in 1933, finding new Tsuga species, Rhododendron niphargum, Primula sikkimensis and several species of Meconopsis and Allium. Several more expeditions were to follow in north-west India and Burma after the Second World War when Kingdom-Ward was in his seventies.

About 120 previously undescribed species have been attributed to this tireless collector. He is best remembered for the many Rhododendron species he described and for the beautiful Asian bird, Ward’s trogon (Harpactes wardii) he named.

He died in 1958 at the age of 72 after suffering from a stroke, and was buried in Granchester, near Cambridge.