Language English Begonia 'Richmondensis' Photo: Jardin botanique de Montréal (Claude Lafond) Begonia 'Tom Ment' Photo: Jardin botanique de Montréal (Claude Lafond) Begonia 'Richmondensis' Photo: Jardin botanique de Montréal (Gilles Murray) Begonia 'Otto Forster' Photo: Jardin botanique de Montréal (Gilles Murray) Begonia 'Lois Burks' Photo: Jardin botanique de Montréal (Gilles Murray) Begonia sanguinea Photo: Jardin botanique de Montréal (Gilles Murray) Begonia engleri Photo: Jardin botanique de Montréal (Gilles Murray) Begonia komoensis Photo: Jardin botanique de Montréal (Gilles Murray) Begonia fischeri Photo: Jardin botanique de Montréal (Gilles Murray) Groupe tabDescriptionJust two genera making up a whole botanical family certainly doesn’t seem like much. Even stranger, the genus Begonia represents 99% of the family – 1,500 species, many of them with very showy foliage and different habits. Some are epiphytes, while others are climbers or shrubs, and some are perennials and other annuals. But all begonias have one feature in common: asymmetrical leaves. HistoryThe first Begonias arrived at the Jardin botanique de Montréal in 1937. But it was mainly between 1956 and 1962 that the collection underwent exceptional growth, thanks to the efforts of the Garden’s first curator, Henry Teuscher, and the collaboration of Edgar Irmscher, one of the great Begonia experts. Irmscher (1887-1968) was a German botanist who published a number of seminal taxonomic studies on this genus. His collection and many of his manuscripts are conserved at the Berlin herbarium. During this period, Teuscher corresponded regularly with Irmscher, and sent him herbarium specimens from the species in the Garden’s collection – mainly plants purchased from dealers or obtained from other botanical gardens. At the time, only a few of the Garden’s Begonia species, sent by C.K. Horich from Costa Rica, had been collected directly in the wild. Over the past several years, the Jardin botanique has significantly increased the number of species in its collection. We have recently obtained several interesting species through the network of botanical gardens, the American Begonia Society, exchanges with experts and excursions to Africa. Where and whenBegoniaceae and Gesneriads Greenhouse: all year long! Based on articles by Denis Barabé in Quatre-Temps magazine. Interesting factsLearn and discoverRhizomatous begonias Currently, more than 650 species and cultivars of rhizomatous begonias are grown primarily for their foliage, which varies widely in shape, texture and colour. The leaves may be peltate (Begonia clypeifolia, Begonia nelumbiifolia), lobed or compound (Begonia carolineifolia, Begonia thiemi). As the name suggests, begonias in this group have a rhizome, which consists of a thick stem with very short internodes. Depending on the species, it may be underground, creeping or upright. The thickness of the rhizomes can range from 0.18 to 8 cm and more. Most rhizomatous begonias bloom from mid-winter to late spring. The degree of flowering, which varies enormously from one species to the next, is sensitive to growing conditions. Most of the rhizomatous species at the Montréal Botanical Garden come from the Americas, but we also have some from the West Indies, Asia, Africa and Oceania. The first species with peltate leaves, Begonia nelumbiifolia, together with Begonia heracleifolia, was discovered in 1830 in Mexico by Ferdinand Deppe and C. J. Schide. The leaves can reach 30 cm in diameter at maturity. Other plants in this group include Begonia carolineifolia, which features a mass of upright rhizomes with compound-palmate leaves. This species, native to Mexico and Guatemala, was introduced to the Saint Petersburg Botanical Garden in 1822. But not all rhizomatous begonias grown today were discovered in the 19th century. Interest in rhizomatous begonias was kindled by the discovery of Begonia bowerae by Thomas MacDougall in 1948. With its small green leaves and black-edged veins, B. bowerae was used to create over 130 cultivars. Thomas MacDougall was an American botanist and explorer who died in 1973 during an expedition to Mexico, a country he visited periodically to collect plants. He discovered several new species of begonias, including B. cavum, B. kenworthyae and B. mazae. During the 1940s, he brought back a species from Mexico, B. thiemi, which Casimir de Candolle described, in the 19th century, as a plant coming from Honduras, but which had remained unknown since then. This begonia has large green compound-palmate leaves, whose petiole can grow to more than one metre long and five centimetres wide. The inflorescence height can reach more than two metres. One of the most beautiful rhizomatous begonia hybrids was created in 1967 at the Jardin botanique de Montréal. Begonia 'Eaglesham' is the result of cross between B. decora and B. masoniana, two Asian species. B. decora, which we grow in a terrarium, has small wine-red leaves. B. masoniana has large sturdy green leaves marked with brown crosses. Begonia ‘Eaglesham’ kept the colours of the first and the sturdiness of the second. We also have some very interesting African rhizomatous begonias, even though they are not as widely cultivated, such as B. quadrialata and B. clypeifolia. B. quadrialata, which must be grown in a terrarium, has tiny leaves with a velvety upper surface. In its natural habitat, it grows in moist areas on rock faces. While seldom cultivated, B. clypeifolia has been known for a long time, since it was described in 1811 by J.D. Hooker. Native to the African tropical forest, this species has a creeping rhizome with glossy green peltate leaves. The flowers are light yellow. Another very fascinating species comes from Asia: B. roxburghii. This begonia, native to the Himalayas and Burma, produces male and female flowers on different plants. Here at the Garden, we have only female plants, which have upright stems with glossy green leaves. Tuberous begonias Description and classification Tuberous begonias are divided into five main types: semi-tuberous bulbous Cheimantha Hiemalis Tuberhybrida Semi-tuberous begonias have a bulb-like swollen area of the basal stem called a caudex. At ground level, the caudex looks like it went through an uncontrolled growth period before forming branches. A good example of a semi-tuberous begonia is the South African species Begonia dregei. Bulbous begonias form bulbs or similar organs. But the only species that grows a bulb is Begonia socotrana, a plant native to Socotra Island that played a pivotal role in the development of Cheimantha and Hiemalis begonias. Cheimantha begonias are hybrids of Begonia socotrana and Begonia dregei, which were first crossed in 1892 to produce ‘Gloire de Lorraine’. These begonias bloom in winter and produce single flowers in shades ranging from white to pink. Some Cheimantha cultivars are difficult to grow and require special care. Hiemalis begonias were created by crossing different species of tuberous begonias with Begonia socotrana. The first hybrid in this group was created in 1833 by John Heal: Begonia Hiemalis 'Mrs. John Heal'. It is a cross between B. socotrana and Begonia ‘Visconte Deneraile’. These begonias bloom in winter and their flowers range from white to pink, from red and apricot to crimson and scarlet. The flowers are single, semi-double or double, depending on the variety. They are bushy, compact and sturdy plants. Some cultivars have upright stems while other tend to be creeping. At the Montréal Botanical Garden, we keep a few Hiemalis begonia cultivars, primarily from the Aphrodite series, which have double pink, red or peach flowers. We still have some specimens from the ‘Nelly Visser’ cultivar, created in 1948. Tuberhybrida begonias, as the name suggests, are of hybrid origin and represent one of the greatest success stories in this area of horticulture. This group is the result of repeated crosses and backcrosses between Andean species. It includes erect and trailing types, with an immense variety of foliage and flowers. The flower measures 4 to 20 cm across and can be single, semi-double or double. The petals are flat or ruffled, and are white, cream, yellow, orange, pink, apricot pink, salmon pink, bright red, deep red or dark purple. There are no blue flowers. Begonias in this group have perennial semi-succulent flattened tubers and stems between 10 and 30 cm long, usually covered with hairs. The leaves have dentate, fringed and ciliate (hairy) margins. Rex-cultorum begonias The colourful, variegated foliage is what makes this group of begonias so popular. It was first developed in 1856 when Begonia rex was crossed with the following Asian species with ornamental foliage: B. annulata, B. decora, B. diadema, B. robusta, B. tenuifolia and B. xanthina. Because of the frequent crosses, the leaves of Rex-cultorum begonias range widely in size, shape and colour. Typical traits are short stems and heart-shaped, sometimes lobed, leaves that come in a variety or a combination of colours, with either silver or green backgrounds and highlights of pink, maroon, chocolate brown and nearly black. The Rex-cultorum begonia collection at the Montréal Botanical Garden consists of nearly 90 cultivars, many of which were obtained in 1980 during the Floralies internationales horticultural exhibition held in Montreal. We also still have some cultivars that predate the 1950s: ‘Fairy’ with salmon pink leaves; ‘Lucy Clossom’ with upright stems; and ‘Peace’ with pale pink leaves. Semperflorens-cultorum (or wax) begonias This group of begonias consists of two categories: natural species and cultivars. The species are themselves subdivided into two types: semperflorens and schmidtiana. The first type, semperflorens, includes Begonia cucullata var. cucullata (B. semperflorens) and other varieties, as well as species that have similar growth habits and requirements. These plants can reach one metre in height. The second type, schmidtiana, includes Begonia schmidtiana and species that are horticulturally similar; they are low growing and compact. Semperflorens cultivars, known as Begonia Semperflorens-cultorum, are popular garden plants that are bushy and compact with slightly succulent stems. The ovate leaves are smooth and glossy and come in shades of green although some varieties have bronze- to black-red leaves. The plants produce abundant, long-lasting white, pink or red flowers. Most Semperflorens-cultorum begonias are easy to grow. The collection at the Montréal Botanical Garden consists of about a dozen cultivars in this group, including ‘Indian Maid’, an early cultivar we received in 1940 that has orange-red flowers; ‘Cinderella’ with cherry red semi-double flowers; ‘Cindy Locks’ with yellow flowers; and ‘Thimbleberry’ with pink or red flowers. Begoniaceae Other types of begonias In addition to the previously described types, begonias can also be shrub-like, cane-stemmed, thick-stemmed, trailing or climbing. Shrub-like begonias are grown primarily for their foliage, which comes in an extraordinary variety of shapes and colours. Begonia acutifolia, discovered in Jamaica in 1688 by Hans Sloane, was probably the first known begonia in this group. The leaves are acuminate, dentate and pubescent. One of the best-known begonias in this group has to be Begonia listada; originally from Brazil, it is grown for its dark green leaves with an emerald stripe down the centre. Two South American species, B. verossa, with its velvety leaves, and B. mollicaulis, with its abundant flowers, belong to this group too, as does B. serratipetala, with its deeply toothed red leaves. The small group of thick-stemmed begonias is grown mostly by collectors and cross-breeders. Begonia dichotoma, discovered in tropical rainforests near Caracas, was introduced to England by Thomas Hoy in 1800. When it blooms, it produces a terminal inflorescence with many tiny white flowers. In 1826, Johnston sent seeds of B. dipetala, a species native to Bombay, India, to the Royal Botanic Garden, in Edinburgh. This species is highly prized by collectors for the large pink flowers that grow from the leaf axil. Begonia olbia, of horticultural origin, is also extremely interesting. The leaves are lobed, dentate and reddish. The upper leaf surface is olive green and slightly pubescent. The flowers are greenish. Another example from this group is B. ulmifolia, originally from the West Indies and South America, which, as its Latin nomenclature indicates, has leaves shaped much like the leaves on the elm it is named for. Cane-stemmed begonias are generally grown for their long, pendant inflorescences. One of the most typical representatives of this group is Begonia coccinea. This species, native to Brazil, was introduced to England in 1841 by William Lobb, the first plant collector to work for Veitch & Sons Nurseries. The stems, which can reach a height of one metre, bear drooping clusters of coral-red flowers. This group also contains the heritage cultivars ‘Président Carnot’ and ‘Lucerna’. The first, named in honour of the then president of the French Republic, was created in 1890 by Crozy, in Lyons. Wettstein, a gardener from Lucerne, Switzerland, created B. ‘Lucerna’ in 1892. These two begonias have tall upright stems and red flowers. The small group of trailing or climbing begonias includes some highly interesting species. These begonias come mainly from South America and Africa. At the Montréal Botanical Garden, the majority of trailing or climbing begonias are grown in hanging baskets. The first species in this group, Begonia glabra, was discovered in 1775 by Fusée Aublet, in French Guyana. This plant has profuse white flowers in spring. We also have some African species, such as B. convolvulacea, B. mannii and B. polygonoides. Also belonging to this group is B. mazae, native to Mexico, with small velvety leaves covered with brown stripes or spots. Edible and medicinal begonias Begonias are more than just ornamental plants. People in Africa, Asia and South America eat the leaves of some species, while in the Mossendjo district of the Congo, the leaves are used as a vegetable. Here are the directions for cooking Begonia ampla: first roll and cut the leaves into thin strips and boil them for twenty minutes, then rinse them in cold water. They can then be mixed with meat or other vegetables. It is dangerous to eat the leaves without first boiling them because they contain calcium oxalate crystals. Chimpanzees and gorillas in Gabon particularly enjoy Begonia mannii, one of their favourite foods. In the southern Chinese province of Yunnan, Begonia fimbristipula leaves are used to make herbal tea; the harvesting and drying of the leaves is a major local industry. Begonias also have some medicinal properties. In New Guinea, Symbegonia moorena herbal tea is used to treat stomach ailments. Symbegonia fulvovillosa is used for mouth ulcers in children and colds; the stems are crushed to release the juice, which is ingested. In South America, begonia syrup or herbal tea is used to treat colds and fever (B. humilis, B. rotundifolia). The late Julia F. Morton, a professor at Miami University, noted that two unidentified species of begonias in Guatemala are used as compresses to heal various cuts and sores. A leaf decoction can also be prepared for stomach ulcers. Hillebrandia sandwicensis This section devoted to begonias would not be complete without a discussion of Hillebrandia sandwicensis. This species, described in 1866 by Oliver, is found on only a few of the Hawaiian Islands, formerly called the Sandwich Islands, hence its species name sandwicensis. The genus was named Hillebrandia after William Hillebrand (1821-1886), a physician who lived in Hawaii for twenty years. He wrote a Flora of the Hawaiian Islands, published in 1888. Hillebrandia has tuberous rhizomes with upright, somewhat downy stems. The palmate leaves are lobed and bear fine bristles. Based on articles by Denis Barabé in Quatre-Temps magazine. Botany and ecologyBotanical and ecological informationBotany Begonias have a tremendous variety of habits, foliage and blooms. Habits Most begonias are small or medium-sized herbaceous perennials. They generally have a thick rhizome or, less frequently a tuber, as in the South African Begonia dregei. One species, Begonia socotrana, native to Socotra Island, has a scaly bulb. The stems of some begonias can become quite woody. For instance, Begonia parviflora (South America) may reach a height of five metres. But because the stem is not sturdy enough to support itself, it uses other plants for support. Certain species, such as Begonia annobarensis (tropical Africa), are annuals. There are upright, trailing, hanging and climbing begonias. A few of them, for example Begonia ampla (tropical Africa), are epiphytes and cling to other plants without ever setting root on solid ground. Foliage Leaf shapes and sizes vary widely across species. They range from the tiny peltate leaf of Begonia quandrialata (tropical Africa) to the massive palmatisect one of Begonia thiemei (Mexico and Honduras), whose petiole can measure up to one metre in length. But the prominent feature of begonia leaves is without a doubt the asymmetric blade that is found in the majority of species. Some begonias, like Begonia sutherlandii (Africa), produce plantlets on the stem or leaves. Flowers Begonias have unisexual male and female flowers that are white, pink, red, orange or yellow and generally bear both on the same plant. However, a number of species, like Begonia roxburghii and B. handelii from Asia, have male and female flowers on separate plants. The male flowers typically have 2 to 4 – infrequently up to 8 – tepals, as well as many stamens that form a rounded or elongated yellow mass in the centre of the flower. The female flowers have 2 to 5 tepals, rarely up to 10. It is easy to differentiate the sex of the flower, even if the styles are the same colour as the stamens. The inferior ovary of the female flower is located beneath the tepals and is usually winged. When no wing is present, the ovary often has highly visible awns. The fruit is usually a dry capsule, though sometimes it is fleshy and looks like a berry. Some begonia species have a rather unusual trait in that the plant is completely leafless when it begins to bloom. The Begonia wollnyi plants at the Botanical Garden typically drop all their leaves in January and February. Although begonias are among the most popular of cultivated plants, little is known about how pollination occurs in the wild. We do know, however, that most cultivated begonias are self-pollinating. Pollination Artificial pollination is a simple way of obtaining seeds. Certain begonias, whose male and female flowers bloom at the same time, are very fertile. A good example is the Mexican Begonia franconis, which reproduces so effortlessly, it is now considered a greenhouse weed. Botanists have not been able to determine exactly what role insects play in pollinating begonias. Bees have been observed visiting both male and female flowers of certain begonias, but doubt exists as to whether they actually transfer pollen from one flower to another. Dr. Lyman B. Smith of the U.S.-based Smithsonian Institution put forward the following hypothesis: the role of insects that visit male flowers is not so much to transfer pollen to the female flowers as it is to release the pollen by touching the anthers. Once released, the pollen is carried by the wind to the female flowers. If this plausible-sounding hypothesis turns out to be correct, it would mean that begonias are pollinated by the wind, but still need insects to release the pollen. Habitat and distribution Begonias are widespread in tropical and subtropical regions, except in Australia and on most Pacific islands. They are found mainly in forested areas, from sea level to 3,000 metres. They generally prefer moist, shady habitats. African Begonias, for instance, grow mainly in tropical rainforests or in mountainous areas with heavy rainfall. They are found in the undergrowth or next to bodies of water, attached to wet rock walls. Some species, however, like Begonia dregei, prefer drier and more open sites. In the New World, species in section Gireoudia are plentiful in the dry forests of Mexico and Central America, colonizing rocky walls and tree trunks. Some rhizomatous species like Begonia heracleifolia and B. multinerva have adapted to deciduous forests, and actually shed their leaves during the dry season. Begonia coccinea, for example, native to Brazil, can tolerate dry spells of up to two months. Begonia classification The genus Begonia is divided into 81 sections for purposes of botanical classification. This is based mainly on the morphological features of the flower, including the type of placentation and the number of tepals and carpels. Their botanical classification is constantly changing, though, with new research findings. While it is very interesting and useful from a botanical point of view, it does not really give an accurate picture of Begonias as they are known in horticultural circles. As new species were introduced and new hybrids created, another classification developed, this one based on the different Begonias’ habit, growing requirements or genetic history. There are four main groups: Semperflorescens-cultorum Rhizomatous Rex-cultorum and Tuberous The history of begonia growing Begonias were first grown outside their native habitats when Begonia minor was imported from Jamaica to England. This species was introduced to the Royal Botanic Gardens at Kew in 1777 by William Brown. A mere five species of begonias were grown up to 1800, but that number rapidly increased. The hugely popular Begonia grandis ssp. evansiana arrived in England in 1804. By the mid-nineteenth century, a wide range of species imported from the West Indies, Mexico and South America were being grown in Europe: Begonia acida, B. castaneifolia, B. cinnabarina, B. coccinea, B. cucullata var. cucullata, B. dregei, B. heracleifolia, B. hydrocotylifolia, B. peltata, B. incarnata, B. maculata, B. malabarica, B. manicata, B. borkeri and B. sanguinea. Begonia x ricinifolia was the first of two hybrids to be created in England in 1847; its parent plants are B. heracleifolia and B. barkeri. The other hybrid, Begonia x erythrophylla, was developed at the Botanical Garden in Berlin around the same time and is the result of a cross between Begonia hydrocotylifolia and B. manicata. The parents of both hybrids are native to Mexico. From 1850 until the early 20th century, a number of new species were discovered and cultivated, including Begonia rex, a Himalayan species that was introduced in 1856. In the latter half of the 19th century, a collection of hybrids known as the Tuberhybrida group were developed from tuberous species native to the Andes. In 1878, two Brazilian begonias, B. cucullata var. cucullata (B. semperflorens) and B. schmidtiana, were crossed for the first time, giving rise to many new hybrids and leading to the creation of the Begonia Semperflorens-cultorum group. In 1880, a new plant arrived in Scotland: Begonia socotrana, named for its native island Socotra, which lies south of the Arabian Peninsula. The Begonia Cheimantha group originated from crosses between B. socotrana and B. dregei. In addition, B. socotrana was crossed with hybrids derived from tuberous species native to the Andes; the resulting Elatior begonias belong to the winter-flowering Hiemalis group. Based on articles by Denis Barabé in Quatre-Temps magazine. Cultivation tips Wax begonias and tuberous begonias Various new cultivars, the result of decades of hybridization, are compact excellent bloomers.