Flora

Flora plant life of an area. More than 6,000 plant species occur in Bangladesh, of which about 300 are exotic and 8 are endemic. Of the total number of plant species 3611 are angiosperms (flowering plants), and 7 are gymnosperms. Ninety-five vascular plants have been rated as threatened, of which 92 are angiosperms, and 3 gymnosperms. About 300 species and varieties of algae have been recorded from freshwater habitats alone. There are many more in brackish water and seawater habitats. The fungal flora are about 275. There are about 250 species of bryophytes in the country. Of the 250 species of pteridophytes, 230 are ferns.

Exploration Botanical explorations in Eastern India, including intensive collections from Sylhet, the sundarbans and Chittagong, were consolidated by Joseph Dalton Hooker (1817-1911) and his companion Thomas Thomson. Hooker's travels were systematically recorded in his Himalayan Journals published in 1855, where he gave a graphic description of the flora encountered on his journey. He undertook a long boat journey from Calcutta on 1st May 1850 passing through Pabna, Dhaka and through meghna upto Chhatak and Sylhet. He also traversed this region partly on foot and partly by boat through Sitakunda, Chittagong, Hatia, Sundarbans and Dhaka on his way back to Calcutta in January 1851. Hooker was also a pioneer in the study of the phytogeography of the Indian subcontinent, and suggested, for the first time, the floristic areas of the region. With the cooperation of a number of eminent botanists, he published his monumental Flora of British India (1872-1897) in seven volumes. Sir George King (1840-1904), the first Director of the Botanical Survey of India, employed plant collectors from 1892 for the regions entirely to the east of bay of bengal. He also initiated a series of monographs on illustrated taxonomic research called Annals of the Royal Botanic Gardens, Calcutta.

Charles Baron Clarke (1832-1908), a teacher of Mathematics at Presidency College, Calcutta (1866), subsequently appointed as Inspector of Schools in Eastern Bengal, wandered two and a half years on boat and made more than 7000 botanic collections from Sylhet, Madhupur jungle and Comilla. He also made collection trips to Barisal, eastern Sundarbans, Dhaka, Jessore and Chittagong. When he was posted in Assam in 1883, he travelled the whole of the province on foot and made extensive collections. Despite shortsightedness, he studied field weeds belonging to Commelinaceae, Cyperaceae and Scrophulariaceae, which resulted in the production of excellent monographs on these groups.

Robert Lawrence Heinig arrived in India in 1895 and served as a forester at Chittagong and the Sundarbans. He collected vast information on the forest flora, which was ultimately incorporated in a working plan for the forests of the Sundarbans, and his compilation entitled, A List of Plants of the Chittagong Collectorate and Hill Tracts published in 1925. JM Cowan published The Flora of Chakaria Sundarbans in 1926 when it was a thriving littoral forest. In addition to serving the Botanical Survey of India in the capacity of an Economic Botanist, IH Burkill became associated with David Prain in a revision of the Asiatic species of yams (Dioscorea) published in the Annals of the Royal Botanic Garden, Calcutta in 1936 and 1938.

A 24-year old gardener, John Gibson, was sent from England by the horticulturist Joseph Paxton in quest of seeds of Amherstia nobilis, a tree from lower Burma (now Myanmar). After reaching Calcutta, he sailed on a boat through Mathabhanga to meet the Ganges, and then to Dhaka and through the Meghna and Surma rivers to Chhatak. From there he proceeded to Khasia hills where he collected a boatload of plants consisting chiefly of orchids. Instead of going to Burma to procure Amherstia he spent his time collecting more orchids as he was promised two saplings of Amherstia by Wallich from the Calcutta Garden itself.

tea plantation in the beginning was not carried out on a commercial scale in Bengal. While Nathaniel Wallich was the Superintendent of the Calcutta Garden, a delegation under his charge including a botanist, William Griffith, and a soil expert, John McClelland made their visit to the Assam Plateau in 1935 to study the conditions under which the tea plants grew there in wild. The first consignment of the seeds was procured from Canton, and a site for a nursery near Sadiya was selected. Later, tea plantations were handed over to the newly established Assam Company. In 1840, a tea garden was established in Chittagong. By 1855, wild tea plants were also discovered at Chandkhani Hills of Sylhet in Bangladesh. The first commercial tea garden in Bangladesh was, however, established in 1857 at Malnicherra Tea Estate, two miles away from Sylhet town.

During the latter part of the 18th century, freight vessels were built in Calcutta using Burma teak (Tectona grandis) brought from Burma. Robert Kyd, the Secretary to the Military Department of Inspection under the east india company, suggested in 1787 that a part of the Calcutta Garden by the side of the river Hughly near Calcutta be set apart for trial plantation of teak. The plantation of teak in the hilly areas of Kaptai and Chittagong was first started in 1871 with seeds brought from Burma; this was the first exotic tree species introduced in the forest.

Contribution of surgeons and missionaries Plant explorations initiated By william roxburgh, a Scottish surgeon of East India Company, resulted in the publication of Hortus Bengalensis in 1814. A revised edition of his Flora Indica came out in 1832. Because of his contribution, he is rightly remembered as the father of Indian botany.

William Carey, who arrived in Calcutta as a Danish Christian Missionary at the end of the eighteenth century, occupies a distinct position in the history of botanical and horticultural research in Bengal, and as a pioneer in paper manufacture and printing press. He edited the three volumes of Roxburgh's Flora India in 1832. While working as an indigo planter in Malda, he mastered the Bengali language. He also started the Agri-horticultural Society of India. His disciple, JO Voigt, took charge of Carey's garden and formed a herbarium, and later compiled a catalogue of Serampur and the Calcutta gardens under the title, Hortus Subarbanus Calcuttensis.

Nathaniel Wallich, the superintendent of Calcutta Garden (1815-1846), made a vast collection of plants of Eastern India and catalogued them himself through lithography. His collection is known as Wallich's Catalogue, and is considered a very important reference work to this day. Another Scottish surgeon, Francis Hamilton who was posted at Pattuahat, 9 km north of Laksmipur in Feni district, studied the vegetation of the Sundarbans. His main botanical survey was carried out in 1798 in the eastern part of the river Meghna and he collected materials from Chittagong. His notes during the survey contained extensive historical, ethnological and geographical information, which was later published in the Edinburgh Journal of Science in 1825-26. When he was promoted to the post of a surveyor in 1807, he was entrusted with the task of preparing a full topographical account. Accordingly, he described the climate, meteorology, history and antiquities of each district; the number and condition of the inhabitants, their food habits, and diseases; and the state of education. He commenced this stupendous task in 1807 with the district of Dinajpur and then the northeastern part of Rangpur.

Robert Wight, yet another British surgeon who entered the medical service of the East India Company in 1819, turned to the vegetable kingdom as a hobby. He learned the art of lithography and applied it in his Icones Plantarum Indiae Orientalis (Illustrations of the plants of Eastern India) which was published in six volumes in 1856. Hugh Cleghorn, a civil surgeon, was a pioneer in plant ecology in India. He studied ecology of different hedge plants and their use in various situations, and later published a paper on sand-binding plants.

William Griffith (1810-1845), an assistant surgeon commenced his collecting trip on boat from Calcutta and arrived at Pabna on the 9th September 1835, from where he passed through rivers and vast jheels and arrived in Sirajganj. From here he proceeded towards Jamalpur, and then down the brahmaputra to Mymensingh. Arriving at Habiganj, he entered the surma and reached Chhattak from where he left for Cheerapunji. During his boat journey, he recorded the marsh and aquatic vegetation of the jheels. He repeated the riverine cruise in 1838, this time arriving at Faridpur, Dhaka, Narayanganj and Laksmipur. He made his journey through Surma up to Terryaghat towards Assam. During his botanical career of twelve and half years he spent a large part of his time in exploring, collecting, studying, and drawing floral specimens.

Having qualified in medicine from Aberdeen and Edinburgh in 1883, David Prain was stationed mainly at the East India Company's factory at Laksmipur on the east coast of river Meghna. He is the author of Bengal Plants (1903) and Flora of Sundribuns (1903).

Plant diversity The Bengal province, according to Hooker (1854) contained only two phytogeographical regions, ie (i) the Gangetic plain, and (ii) the littoral-forests of the Sundarbans. It has been estimated that there are about five thousand angiosperm (flowering plants) species in Bangladesh.

Plainland plant diversity The Bangladesh plains are famous for their fertile alluvial soils which support extensive cultivation. Weed flora, both indigenous and exotic, thrive well in the marginal lands (eg isles, passageways) and waste places. Clerodendrum viscosum (Bhat), Glycosmis arborea (Dantmardan), Heliotropium indicum (Hatishud), Xanthium strumarium (Ghagra), Alternanthera sessiles (Sechi), Lippia nudiflora (Bhuiokda), and Croton bonplandianum (Panimarich) are frequently encountered in the region.

Tagar, Tabernaemontana coroneria

Ghaghra, Xanthium strumarium

Golpata, Nypa fruticans

Shaluk, Nymphaea stellata

Various water bodies and wetland ecosystems provide habitats for diverse kinds of aquatic plants (hydrophytes), eg Potomageton (Ghechu), Lemna (duckweed), Pistia (Topa pana), Hydrilla, Vallisneria (dog grass), and various insectivorous plants including Utricularia (Jhanji). Floating ferns like Salvinia and Azolla grow in profusion, particularly in ditches, canals and ponds. Almost throughout the country the introduced floating plant, water hyacinth (Eichornia crassipes) grows profusely and often becomes a troublesome weed in the agricultural land. The beautiful flowers of water lilies (both white and blue) and the sacred lotus (Nelumbo nucifera) depict a scenic beauty during the rainy season.

Tall grasses like Erianthes rivenae (Nal), Phragmites karka (Khagda), Arundo domax and Saccharum spontaneum (Kash), predominate in marshes, haors, baors and riverbanks. These are mixed up with varying proportions of Typha angustata (Hogla), Imperata cylindrica (Shon) and various species of sedges (Cyperaceae).

Forest plant diversity Village homesteads, sparingly distributed all over the country, provide a green scenario amongst the network of rivers and rivulets and can be designated as village or homestead forests. These are characterized by banana (Musa species) and bamboo (Bambusa species) thickets, associated with a few other fruit yielding trees (eg mango, wood apple, betel nut, coconut and palmyra palm), fuel (eg barun, koroi, etc) and timber-yielding (eg koroi, debdaru, chhatim, etc) tree species.

The littoral of Bangladesh, often known as the Sundarbans, lie in the southwestern parts of the country, in the confluences of Raimangal River and various other tributaries. Predominant species are sundari (Heritiera fomes) and Gewa (Excocearia agallocha), mixed with varying proportions of Kankra (Bruguiera gymnorhiza), Baen (Avicennia species), Possur (Carapaspp) and keora (Sonnerata species). Open places along the banks of rivers and creeks in less saline areas, a conspicuous feature of the forest, mark the gregarious occurrence of two palms eg Golpata (Nypa fruticans) and Hetal (Phoenix paludosa). Mudbanks and creeks harbour clumps of thorny Hargoza (Alanthus ilicifolius), while Bhola (Hibiscus tiliaceous) forms a dense mass of entangled growth on the forest floor. Although many grasses, epiphytic orchids, and ferns are quite common in this forest, absence of bamboos is a conspicuous feature of this mangrove ecosystem.

The occurrence of tree fern (Cyathaea species) in the natural forests of Sylhet district is a notable phenomenon. Haor vegetation of this region represents typical freshwater swamp forests, characterized by Hijal (Barringtonia acutangula), Karanja (Poungamia glabra) and innumerable free-floating submerged rooted, and rooted floating hydrophytes.

Plainland forests, represented by Dhaka-Tangail-Mymensingh 'Sal' forests, mostly belong to secondary coppice formations. This forest is dominated by Sal (Shorea robusta) trees, often admixtured with other minor tree species like Bahera (Terminalia belerica), Haritaki (T. chebula), Chalta (Dillenia pentagyna), Koroi (Albizia spp.), Sonalu (Cassia fistula), Kurchi (Holarrhena antidysenteria) and Kumbhi (Careya arborea). The undergrowths were once quite rich and diverse with Zingibers (mostly Curcuma zedoaria), ground orchids, palms (Phoenix acaulis), several grasses and other weedy species. Climbers are lofty, chief amongst them are Spatholobus roxburghii, Bauhinia vahlii, mixed with members of Kumarika (Smilax macrophylla), Chaprialu (Diosorea spp) and species of Vitaceae. Gradual encroachments and manifold anthropogenic activities (notably clear felling, leaf-litter collection and uncontrolled extraction) are major threats resulting in depleting and vanishing plant resources of these forests.

The forests of Chittagong and the Chittagong Hill Tracts are known to be evergreen and semievergreen types with a preponderance of deciduous species. Once famous for their storyed nature, species richness and diversity, the forest resources are now depleting at an alarming rate, owing to illegal felling, cutting, shifting cultivation and other anthropogenic activities. Topmost storey consists of Garjan (Dipterocarpus species.), Telsur (Hopea odorata), Chapalish (Artocarpus chaplasha), Chundul (Tetrameles nudiflora) and various species of Albizia (Koroi). Lower storey includes species of Lagerstroemia (Jarul), Toona (Toon), Syzygium (Jam), Elaeocarpus (Jalpai) and Glochidion. Lianas, epiphytes (mostly of orchids, asclepiads, ferns and leafy mosses) and harbaceous undergrowths are abundant. Kassalong Reserve is noteworthy for bamboo brakes in large areas, mainly occupied by Meloccana baccifera (Muli), Bambusa tulda (Mirtinga) and Dendrocalanus longispathus (Orah). Savannah formations can be met within open places, along the banks of rivers and swamps with common tall grasses like Saccharum spontaneum (Kans), Imperata cylindrica (Shon) and Vetiveria zizanoides (Bena).

Marine plant diversity Marine algae resources, particularly in the Bay of Bengal estuaries and st martin's island, are quite rich and diverse, but these are being indiscriminately extracted and over-exploited, causing serious depletion of these resources.

Agricultural crop diversity Bangladesh is predominantly agrarian and is rich in germplasm resources of some of the world's most important crops such as rice, jute, sugarcane, tea, potato, amaranth, banana, brinjal, chilli, cotton, bean, lime, litchi, taro, yam, bamboo, rattan, etc. The degree of genetic erosion, as a consequence of adoption of modern varieties (and of monoculture practices) and degradation of cultivable lands, has not yet been properly documented. Agroecotypes and their adaptability, land races and their characteristics through 'gene hunting` necessary for all these crop species have not been evaluated. The best known crop is rice, which is estimated to have about 10,000 different cultivars. On the other hand, the wild genetic resources, especially the wild relatives of the existing crop species of Bangladesh are not adequately known. [ABM Enayet Hossain]

Bibliography Jd Hooker, Himalayan Journals or Notes of a Naturalist in Bengal, The Sikkim, The Nepal Himalayas, etc, 1854.

Economic plant plant or plant products used in trade, commerce, or industry. The number of species of most economic plants in the world is estimated to be about 5,000. Of the flowering plants growing in Bangladesh, about 320 plants are economically important. Of them 150 crops are considered most economic. Among economic plants cereals such as, rice, wheat, barley and some millets are cultivated widely. After rice the most economic plants are jute, tea, and sugarcane. Jute and tea are major cash crops. The other economic crops are oil seeds, potato, sweet potato, tobacco, cotton and several pulses. A large number of plants are cultivated as fruit crops. jackfruit and mango are the most abundant and popular of these plants. The other common but economic fruits are blackberry, guava, pineapple, litchi, banana, coconut, Indian jujube, papaya, sapodilla, some citrus, watermelon and cucumber, custard apple, bullock's heart, wood apple, and pomegranate. linseed, rape, sesamum, niger, peanut, and safflower are the most important oil yielding plants.

The most common vegetable yielding plants are cucurbits, brinjal, tomato, okra, papaya, beans, spinach, radish, cabbage, cauliflower, amaranth, Indian spinach and yam. The economic timber-yielding plants are teak, garjan, sal, gamar, sundari, koroi, rain tree, civit, jarul, sisso and telsur. Areca nut and betel nut are also cash crops, mostly used as masticatories. Some spice plants are also used as cash crops. The common spice plants are ginger, garlic, onion, tarmeric, coriander, black cumin, chilli, black pepper, Indian cassia, and fenugreek. Many species of bamboo and rattan are used in making various household commodities. Several species of bamboo, gewa and koroi are used as raw materials for making pulp and paper. Kath, a dye, is extracted from kath plant. Many plants such as dahlia, rose, phlox, salvia, jasmine, gandharaj, merry gold, China rose, and zinnia are used as ornamental plants. Palmyara palm and wild date palm trees are also very popular for sweet exudate. Few non-flowering plants are also considered economic. These are some mushrooms and a marine algae, Hypnea. Few species of pteridophytes are used as vegetable or as ornamental plants, such as Selaginella, Nephrolepis, Adeantum and Asplenium. Recently, few economically important exotic plants such as maize, soybean, mahogoni, Acacia, sunflower, grape, and rubber plant are being cultivated in Bangladesh. [Mostafa Kamal Pasha]

Medicinal plants The total number of plants with medicinal properties in the subcontinent at present stands at about 2000. About 450 to 500 of such medicinal plants have so far been enlisted as growing or available in Bangladesh.

Some common medicinal plants of Bangladesh.
Ulatkambal, Abroma augusta	Nayantara, Catharanthus roseus Mehedi, Lawsonia inermis	Kurchi, Holarrhena antidysenterica

Table 1 Some common medicinal plants of Bangladesh.
Local name	Scientific name	Uses
Ulatkambal	Abroma augusta	Emmenogogue; used in amenorrhoea and dysmenorrhoea.
Muktajhuri	Acalypha indica	Expectorant, emetic, diuretic; used in bronchitis and asthma.
Apabg	Achyranthes aspera	Purgative, diuretic, ecbolic, hypoglycemic; used in renal dropsy, piles, anasarca, boils and other skin eruptions.
Basak	Adhatoda zeylanica	Expectorant, bronchodilator, used in cough, asthma, bronchitis, pneumonia, phthisis and respiratory problems.
Bel	Aegle marmelos	Digestive, stomachic, laxative, astringent; used in constipation and dysentery.
Rashun	Allium sativum	Carminative, diuretic, hypotensive, used in indigestion, hypertension and diabetes.
Chhatim	Alstonia scholaris	Febrifuge, antiperiodic, astringent, anthelmintic, hypotensive; used in fever, hypertension, diarrhoea and dysentery.
Kalomegh	Andrographis paniculata	Febrifuge, alterative, stomachic, anthelmintic, cholagogue; used in liver diseases, colic, fever, diarrhoea and dyspepsia.
Xatamuli	Asparagus racemosus	Roots aphrodisiac, alterative, diuretic; promotes lactation; also used in diabetes.
Neem	Azadirachta indica	Antiseptic; used in fevers, boils, ulcers, eczema and other skin diseases.
Brahmixak	Bacopa monniera	Blood purifier, brain-, nerve- and cardiac tonic, diuretic; also used for epilepsy.
Nayantara	Catharanthus roseus	Used in blood cancer, Hodgkin’s disease and diabetes.
Thankuni	Centella asiatica	Leaf juice is used in cataract and other eye diseases; plant is used in dysentery, internal and external ulcers, convulsive disorders.
Babchi	Cullen corylifolia	Seed extract is used in leucoderma, leprosy, psoriasis and inflammatory skin diseases.
Kalo Dhutra	Datura metel	Narcotic, anodyne and antispasmodic; leaves used in spasmodic asthma, colic, sciatica painful tumours, glandular inflammations.
Ayapan	Eupatorium triplinerve	Haemostatic and antiseptic; used in ulcers and haemorrhages and also as cardiac stimulant, emetic, diaphoretic and laxative.
Anantamul	Hemidesmus indicus	Alterative, sudurific, diuretic and blood purifier; used in abdominal tumours.
Kurchi	Holarrhena antidysenterica	Antidysenteric, astringent, stomachic and anthelmintic. Fruits are hypoglycaemic.
Chalmoogra	Hydnocarpus kurzii	Seed oil is used as a cure for leprosy and other skin diseases.
Mehedi	Lawsonia inermis	Paste of leaves and bark is used in burns and scalds, dandruff and various other skin diseases. Decoction in jaundice.
Sarpagondha	Raulwolfia serpentina	Roots are used as remedy for hypertension, insomnia, anxiety, excitement and insanity.
Ashoke	Saraca asoca	Strongly astringent and uterine sedative; used in menorrhagia, haemorrhoids and ulcers.
Arjun	Terminalia arjuna	Bark is hypotensive, cardiac tonic, astringent and febrifuge; has tonic effect on liver cirrhosis.
Methi	Trigonella foenum-graecum	Diuretic, carminative, emollient, tonic; used in menstrual disorders, diabetes, hypertension and sexual problems Axwagondha || Withania somniferum || Roots are used in headache, convulsions, insomnia, hiccup, coughs and dropsy.
Ada	Zingiber officinale	Rhizome is carminative, stomachic, digestive; used in dyspepsia, vomiting, loss of voice, coughs, sore throat and fever.

[Abdul Ghani]

Indigenous knowledge associated with herbal medicine In traditional systems, indigenous knowledge (IK) plays a central role in disease diagnosis and health care practices. Rapid westernisation and introduction of modern medicine, in many places, has affected not only the traditional system but also the IK associated with it. Especially in areas with rapid urbanization, IK the traditional medical system have become seriously vulnerable. The risk is not so great for well-documented and codified systems such as the Ayurvedic, Hekimi and Unani ones but many undocumented systems or folk medicine, which have been handed down from one generation to the next by word of mouth are in grave danger. The Kaviraji system in the villages is an example of the IK based folk medicine, which has been used and appreciated since prehistoric times.

Data reported from 10 villages in northern Bangladesh indicate that of the ailing persons surveyed, 30 percent adopted the traditional system; and of the 150 medical practitioners surveyed, 38 percent were herbalists using IK. In Bangladesh, there are over 5000 registered practitioners, in addition to about 3000 unregistered herbalists.

IK based folk medicine constitutes a very diverse stream in Bangladesh and is ecosystem and ethnic community specific; different localities have different characteristics. For example, elderly housewives or ladies administer home-based remedies through plants using IK on disease, poor health or especial conditions like pregnancy. The herbal healers, Kaviraj or Boydya, offer IK based remedies for diseases and ailments; there are thousands of them in Bangladesh averaging 4 to 5 in large villages; ethnoveterinary practitioners treat domestic animals following IK and local plants; bone setters are traditional orthopedics specializing in treating broken bones using IK; poison specialists are experts in treating snake bites, scorpion bites, dog bites, etc. Traditional birth attendants, or Dais, have IK on normal deliveries.

The rich heritage of IK associated with herbal medicine is considered as the root of all systems of traditional remedies in Bangladesh. During the course of development in the remote past, a particular remedy discovered became widespread, and subsequently tested, refined, revised, improved upon, and gradually incorporated in the traditional codified system among the practitioners. A vast number of the folk remedies, however, remained endemic to the societies of various ecological regions as their IK and often survived the ravages of time, and were transmitted only through words of mouth. But with the onset of modern medicine, and with people moving away from their indigenous plants, many such IK based remedies have been fast eroding. [M Iqbal Zuberi]