Addition of three new angiospermic taxa to the flora of Bangladesh

: During updating the plant holding database of the botanical garden, Bangladesh Agricultural University, the authors identified three species of the family Commelinaceae namely, Callisia fragrans (Lindl.) Woodson, Murdannia gigantea (Vahl) G.Brückn. , and Tradescantia sillamontana Matuda as new records to the flora of Bangladesh. This paper provides a comprehensive description and colour photographs of these species from Bangladesh.

The dayflower or spiderwort family Commelinaceae is widely distributed throughout tropical and subtropical regions comprising 41 genera and 731 species (Christenhusz & Byng 2016) and is characterized by several features including a distinct closed leaf sheath, a succulent leaf blade, deliquescent three-merous flowers with distinct petals and sepals and a lack of nectaries (Cronquist 1981). The members of this family are important for their valuable ornamentals such as dayflower, spiderwort, moses-in-the-bulrushes, and wandering Jew; young shoots and leaves as vegetables, as well as for their medicinal uses as a laxative, to treat inflammation of the eyes, fractured bones, burns, arthritis, skin & oncological diseases, tuberculosis & asthma, among others (Alam 2007;Tan et al. 2014). Khan & Alam (1977) reported 28 species under 13 genera of the Commelinaceae from Bangladesh. After some nomenclatural changes, later the family was exemplified from the country by 10 genera and 27 species (Alam 2007). Recently, Alam & Uddin (2018) recorded 23 species under 10 genera of Commelinaceae from the greater Chittagong and the Chittagong Hill Tracts. All these reports include taxa both from wild and cultivated states.
The Botanical Garden of Bangladesh Agricultural University (BAUBG) is located on the western bank of the old Brahmaputra River between 24.433°N and 90.263°E. Since its inception in 1963, the BAUBG has been involved in the collection and conservation of plant genetic resources from both local and international sources. With a land area of about 10 ha, approximately 1,150 plant species under 327 genera and 215 families are being conserved here over a period of time for the study by students, academicians, and researchers (Sarwar 2019). The garden's collections were primarily acquired through field / forest exploration; however, some species were acquired through exchange programmes and/or from commercial nurseries. Although BAUBG collection is enriched day by day and the database is well-managed, some of the plant collections have been J TT lost due to different natural calamities, diseases, insect predation, and theft. These necessitate initiating a new programme to update the plant holding database of the BAUBG (Sarwar 2019;Ashrafuzzaman & Sarwar 2021;Ashrafuzzaman et al. 2021).
This article includes taxonomic descriptions of the species, including the most recent nomenclature and the most frequently used synonyms, as well as information on flowering and fruiting time, ecology, mode of propagation, uses, global distribution, and conservation status.

Methods
A detailed survey on the plant genetic resources growing and conserved throughout BAUBG has been carried out through frequent visits. During these visits, fresh flowering samples were collected; herbarium specimens were prepared as vouchers by drying the fresh samples following standard procedure (Anonymous 1996). The dried specimens were mounted on the herbarium sheet and preserved in Prof. Arshad Ali Herbarium at the botanical garden, Department of Crop Botany, Bangladesh Agricultural University (AAHBAU). The collected fresh (or dried) specimens were identified in the field or by comparing with herbarium specimens or pertinent published literature. While updating the list of the family Commelinaceae, the authors came across a few interesting specimens which, after critical examination and with help of web resources and type specimens, were identified as Callisia fragrans (Lindl.) Woodson, Murdannia gigantea (Vahl) G.Brückn., and Tradescantia sillamontana Matuda. A comprehensive description and colour photographs are provided for easy identification of the species. The botanical names were updated following WFO-The World flora online <http://www.worldfloraonline.org> (older http://www. theplantlist.org) and Plants of the world online <https:// powo.science.kew.org/>.

Results and Discussion
While updating the list of Commelinaceae species conserved at BAUBG, we identified three new species to the flora of Bangladesh: Callisia fragrans (Lindl.) Three species of Commelinaceae recorded as new to the flora of Bangladesh are described below.
Uses: Planted as an ornamental in many parts of the world.
Distribution: Native range is Madagascar, tropical Asia to northern Australia, cultivated in India, Sri Lanka, Singapore, Cambodia, Viet Nam, Thailand, Lao People's Democratic Republic, Myanmar, Sri Lanka, Indonesia, Papua New Guinea, Philippines, China, Australia and Madagascar. In Bangladesh, it is so far recorded in cultivation only.
Conservation status: Murdannia gigantea is currently known only in cultivation state; hence no threat has been assessed and is considered as Least Concern.
The species can easily differentiate with tall flowering shoot terminal in the rosette with leafy internodes; broad leaves.
Ecology: Almost succulent and nearly xerophytic in nature.
Mode of propagation: Can be easily propagated through stem cuttings.
Uses: Grown as indoor pot plants. It can also be grown as a ground cover.
Distribution: Native to Mexico, Italy, USA, Brazil, Spain, Argentina, South Korea, Norway, Chinese Taipei, South Africa, Belgium, Greece, Nicaragua, El Salvador, India. In Bangladesh, it is so far recorded in cultivation only.
Conservation status: Tradescantia sillamontana is currently known only in cultivation state; hence no threat has been assessed and is considered as Least Concern.
Easy to recognize by its distinctive feature being the

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