Popular Ornamental Plants

Plant Biotechnology

Canna, Canna glauca

Introduction Canna glauca is a species of the Canna genus, the only member of the family Cannaceae. The closest living relations to cannas are the other plant families of the order Zingiberales; that is the gingers, bananas, marantas, heliconias, strelitzias, etc. The species have large, attractive foliage and horticulturists have turned it into a large-flowered, brash, bright and sometimes gaudy, garden plant. The name Canna originates from the Celtic word for a cane or reed. Botany It is a perennial-ponds and aquatic plant growing up to 1.5 m. In tropical and subtropical regions, it is in flower from August to October, and the seeds ripen in October. The flowers are hermaphroditic and in variety of colours: yellow; burnt orange with white edged leaves; red with purple brown edged leaves; and salmon pink. The flowers are composed of three sepals and three petals that are seldom noticed by people, they are small and hidden under extravagant stamens. New shoots rise at intervals from the slowly creping roots like sprouting stem of bamboo, giving a plant a continuously lush appearance. Although gardeners enjoy these odd flowers, nature really intended them to attract pollinators collecting nectar and pollen, such as bees, hummingbirds and bats. In the last three decades of the 20th century, Canna have been categorised by two different taxonomists, Paulus Johannes Maria Maas from Netherlands and Nobuyuki Tanaka from Japan. Inevitably, there are differences in their categorisations. Both agree that C. glauca is a distinct species, but in addition, Tanaka also recognises a separate variety. Origin and Adaptation It originates from the wetlands of tropical America/New World and was introduced to England in 1730. T.N. Khoshoo and Iva Mukhejee reported during the 44 years: 1848 to 1892, the speed of evolution was rapid and its direction governed by the following principles of selection: increase in hardiness, reduction in height, spikes well above foliage, free

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Plant Biotechnology

flowering, erect flowers, increase in flower size, colour diversity, circular form of flowers, increase in thickness of flower parts and durability of flower, self shedding flowers, etc. The result has been the transformation of C. glauca from simple foliage plants to attractive ornamental flowers. Canna glauca var. siamensis (Kraenzl) Nb. Tanaka, 2001 (pic) is a contentious variety as it occurs widely in South and Southeast Asia, where it is supposed to have differentiated within the past few centuries. According to Jean-Baptiste Lamarck and Nobuyuki Tanaka, C. glauca have been grown for a long time in Southeast Asia, India, and Africa, with both species imported from Central and South America. It has exotestal layer composed of Malphigian cells from tegumentary, raphal, and chalazal layers, which provide mechanical protection and a physical barrier to imbibition. However, the seed are able to absorb water after the raising of the preformed imbibition lid on the raphe, a structure unique to C. glauca. During imbibition, exotesta looses its hardness, allowing the embryo to emerge. Since it has multilayer, very hard, and durable seed coverings, it is likely that seed remains would have survived in water-logged soil. Seeds from archaeological sites of an age of 600 years have proved still viable. Cultivation The species prefers light (sandy), medium (loamy) and heavy (clay) soils and requires welldrained soil. The preferred soil is weak acid with pH 6 to 6.5. It cannot grow in the shade and requires moist soil. It was propagated by dividing rhizomes, tubers, corms or bulbs (including offsets). The rhizomes transplant and divide easily any time of year. They also spread on their own by branching, so one plant eventually becomes a cluster of many plants. They usually sprout in 7 to 14 days. Generally C. glauca are free of diseases and pest. However, they may fall victim to fungus (symptom called canna rust) and Canna specific viruses. Treatment is to simply remove the old leaves or flowers that are affected. Uses Canna glauca are one of the most popular garden plants and a large horticultural industry depends on the plant. The rhizome is rich in starch, and it has many uses in agriculture. All of the plant has commercial value, rhizomes for starch (consumption by humans and livestock); stems and foliage for animal fodder; young shoots as a vegetable; and young seeds as an addition to tortillas. In more remote regions of India, cannas are fermented to produce alcohol. The plant yields a fibre - from the stem - it is used as a jute substitute and making paper. In Thailand, C. glauca are a traditional gift for Father's Day. References Cooke, I. 2001. The Gardener's Guide to Growing Cannas. Timber Press, Portland, Oregon, USA. Fang, Y., Hua, W.P., Qing, X.S., Guang, Z.W., and Hua, F.D. 2004. Technique of Scarifying and Fermenting Process of Canna Starch. Southwest China University Journal of Agricultural Sciences. 17 (2): 231-234

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Plant Biotechnology

Khoshoo, T.N. and Guha, I. 1976. Origin and Evolution of Cultivated Cannas. Vikas Publishing House, New Delhi, India. Khoshoo, T.N. and Mukherjee, I. 2004. Genetic Evolutionary Studies on Cultivated Cannas. Theoretical and Applied Genetics. 40 (5): 204-217. Kubitzki, K. and Huber, H. 1998. Flowering Plants: Monocotyledon Alismatanae and Commelinanae (except Gramineae). Springer, New York, USA. Ogden, S. 2007. Garden Bulbs for the South. Timber Press, Portland, Oregon, USA. Tanaka, N. 2001. Taxonomic Revision of the Family Cannaceae in the New World and Asia. Makino Botanical Garden. 1: 1-74. http://www.pfaf.org/database/plants.php?Canna+glauca (120909)

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Plant Biotechnology

Orange Jessamine, Murraya paniculata

Introduction Murraya paniculata is often sold as a jessamine plant that belongs in the Murraya genus. The Murraya genus contains 12 species in the family Rutaceae, which also includes curry tree. Orange jessamine belongs to the same species as Murraya alata (Drake). Botany Orange jessamine is an evergreen tree which usually heights to 2 to 3 metres. It bears pinnate leaves of three to nine ovate leaflets that are three to four centimetres and has a darn-green colour with a stiff texture. The tree produces white flowers borne in a small cluster near branch ends that have five petals each. A red elliptic fruit of about one centimetre develops to produce one or two seeds that are tear-drop shaped. Certain orange jessamine can form multiple roots and abundant fine roots. It is a plant that does not require of special pollinators as it can self-pollinate. However, the seeds are usually dispersed by the help of animal vectors: birds. Origin and Adaptation The plant is found from India and China through South East Asia to Malaysia and Northern Australia. It has an alluring fragrance due to which it is cultivated throughout the tropics and subtropics. Murraya paniculata adapts to a wide range of conditions. Naturalized plants in Puerto Rico grow in areas receiving 750 mm to 1900 mm of annual precipitation. It takes more likings to the alkaline soil. Orange jessamine can grow on most well-drained soils derived from both sedimentary and igneous rocks. It also can grow from nearly sea level to elevations of 1300 m. Under the shade, it can produce few flowers or fruits and are therefore known as moderately intolerant of shade.

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Plant Biotechnology

Seedlings do not compete well with grass or herbaceous vegetation. In the wild, orange jessamine contributes to the biodiversity, protects the soil, and furnishes food and cover for wildlife. The plant flowers throughout the years and produces small, fragrant flower clusters which attract bees, while the fruits attract small fructivorous birds. Cultivation Germination usually takes place hypogeneously where it has a floral part, while nursery production is by seed, cuttings, and air-layers. Seedlings quickly develop deep root systems and grow at moderate rate. Propagation is easily done by seeds and not so easily by softwood cuttings. Orange jessamine plants can live at least 15 years and need little care. The species has not yet been reported to be a weed in any area, but it can be killed with herbicides recommended for broad-leaf weeds, by girdling, or by grubbing out the plants. Murraya paniculata is vulnerable to soil nematodes, scales, sooty molds, and whitefiles. It is also the preferred host to the insect pest Diaphorina citri (citrid psyllid), which is responsible for the citrus greening disease. Uses Murraya paniculata is a popular ornamental plant in the tropics. It can be pruned into animal and other shapes, pruned into tree form, grown as a potted plant or cultivated as a bonsai. The leaves and other tissues have both stimulant and astringent properties and are used to treat diarrhoea, dysentery, cuts, joint pain, body aches, venereal disease, and as a abortive. In addition to essential oils, tissues of orange jessamine contain the indole alkaloid yuehchukene and at least eight highly oxygenated flavones. References Huang, K.C. and Williams, W.M. 1999. The Pharmacology of Chinese Herbs. CRC Press, Boca Raton, Florida, USA. Kimura, T and Paul, P.H. 1998. International Coalition of Traditional and Folk Medicine: Northeast Asia Part I. World Scientific Publishing Co, Singapore. http://www.gmbonsai.com/index.php?option=com_content&task=view&id=104&Itemid=40 (120909) http://hort.ufl.edu/shrubs/MURPANA.pdf (140909)

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Plant Biotechnology

Chris Plant, Euphorbia milii

Introduction Euphorbia milii, also known as Christ plant or Crown of Thorns is from Crassulacease and Euphorbiaceae family. This euphorbia, among the 2000 or more known species of the spurge family, is an old trooper. It is classified as a succulent, a plant with thick fleshy leaves and stems adapted for water storage. Botany The stems are 5-7 sided, greyish brown, branched and up to 2-3 inches in height with many prominent grey 1 inch spines. The leaves tend to be obovate (wider near the tip), up to 1½ inch in length, but much larger (up to 6 inch) in the Thai hybrids. They have a smooth edge, are spirally arranged on the stem, and range from bright green to greyish green. Foliage is produced on new stem growth. The inflorescence is composed of a specialized structure termed a cyathium comprising a cuplike involucre, within which is set a single much reduced female flower surrounded by three male flowers reduced to single stamens. The cyathia are borne in clusters (cymes) and each cyathium. They produce flower throughout the year. It also has tiny flowers which look like petal-like bracts and come with the color of red, yellow, white, pink, and orange. There are few serious pests: scale insects and mealy bugs are most frequently seen, with spider mites and thrips an occasional problem. These problems are easily combated with regular cleaning of dead and dried leaves. Origins and Adaptation Euphorbia milii is not fussy, and can produce cheery bracts of orange to salmon-pink and white-red all year round. It is native in Madagascar, where it grows happily in granite crevices, reaching up to 40 inches, though as a houseplant it rarely exceeds this height. Its long thorny branches are about as thick as a little finger and are easily trained over a hoop. The plant has adapted to dry conditions where little amount of water is available. Alike 6

Plant Biotechnology

cactus, it has thorns and tolerates the dry seasons well. It does not need watering often and grows well in dry well drained soils. Cultivation Crown of Thorns is usually propagated from tip cuttings. Euphorbia milii is a drought tolerant plant. It requires low humidity and the soil needs to dry before watering. It should be kept away from excessive rainfall. It can also tolerate a minimum temperature of 15°C. Meanwhile, Euphorbia milii grows and blooms better with maximum amount of sunlight, random tip cutting, moderate amount of fertilizer, and planting it with some distance between one and another. During the flowering period it will do well in average home temperature (20°-30°C). Uses Due to the ease in requirements, Euphorbia milii has been used fondly as a decorative plant. Euphorbia milii is poisonous, particularly the juice from its woody stems. Its latex is a potent plant molluscicide and a promising alternative to niclosamide. It has been used in human and veterinary medicine as a drug of choice to treat several tapeworm infections. References De-Carvalho, R.R., Maldonado, A., Oliviera-Filho, E.C., Ribeiro, A.C., Paumgartten, F.J.R., and Rey, L. 1998. Effects of Euphorbia milii Latex on Schistosoma mansoni Eggs; Miracidia and Cercariae. Memorias do Instituto Oswaldo Cruz. 93 (1): 235-237. Spencer, R. and Pearson, S. 2002. Horticultural Flora of South Eastern Australia. UNSW Press, Sydney, Australia. Zachos, E. 2005. Tempting Tropicals: 175 Irresistible Indoor Plants. Timber Press, Portland, Oregon, USA. http://miami-dade.ifas.ufl.edu/pdfs/ornamental/ornamental_publications/crown-of-thornshomeowner.pdf (140909) http://www.weekendgardener.net/2006/11/crown-of-thorns-euphorbia-milii.htm (140909) http://www.greenpatio.com/plantdatabase/euphorbiamilli.shtml (140909) http://www.skh.com/PlantCare/euphorbia_milli.pdf (130909)

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