Southeast Asia (Myanmar, Thailand, Cambodia, Laos, Vietnam, Malaysia, Singapore, Brunei Darussalam, Indonesia, Timor Leste, the Philippines and Papua New Guinea) is a region of high plant diversity with an estimated 50,000 flowering plant species. Estimates of plant diversity in the region continue to grow as large numbers of new species are described even though there have been suggestions that there are few new species to be Gard. Bull. Singapore 71 (2) 2019 268 found in some parts of Southeast Asia. It is likely that most estimates of species numbers in the countries of Southeast Asia are too low due to the lack of taxonomic work on groups which have many locally endemic species. Differing collecting densities across the region can profoundly affect our understanding of plant diversity and lead to large underestimates of species diversity in poorly collected countries and regions. Progress on each of the major Flora projects in Southeast Asia, Flora of Thailand, the Flora of Cambodia, Laos and Vietnam/Flore du Cambodge, du Laos et du Viêtnam, Flora Malesiana, Flora of Peninsular Malaysia, Tree Flora of Sabah and Sarawak, Flora of Singapore and Flora of Vietnam, along with floristic research in Myanmar, the only country not covered by at least one of these Flora projects, is discussed. In addition to the formal Flora projects, there is much floristic activity occurring in the countries otherwise covered by transnational Floras.

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Progress on Southeast Asia’s Flora projects

The Flora of the Malay Peninsula, Vol. III.

........................................................................................................................ ii Lay Summary ................................................................................................................. iv Acknowledgements ........................................................................................................ vi Chapter

Molecular species delimitation, taxonomy and biogeography of Sri Lankan Gesneriaceae

Aeschynanthus (Gesneriaceae), a genus comprising approximately 160 species in subtropical Southeast Asia, has red, tubular flowers, typical of a sunbird pollination syndrome. A. acuminatus, the species that is distributed extending to the northern edge of the genus, where the specialized nectarivorous sunbirds are absent, possesses reddish-green flowers and a wide-open corolla tube, flowering time shifts from summer to winter and the species achieves high fruiting success. This atypical flower led us to investigate the pollination biology of this species. Three species of generalist passerines, Grey-cheeked Fulvetta (Alcippe morrisonia, Sylviidae), White-eared Sibia (Heterophasia auricularis, Leiothrichidae) and Taiwan Yuhina (Yuhina brunneiceps, Zosteropidae), were recorded visiting A. acuminatus flowers. Pollination effectiveness was quantified via conspecific pollen presence on stigmas and natural fruit set. The significantly high natural fruit set (60%) and conspecific pollen transfer rate (94%) indicate high reproductive success facilitated by the accurate pollen placement on the birds. The existence of copious (61 µL) and highly diluted (7%) hexose-dominant nectar, together with a major reflectance peak of corolla lobe in the long-wavelength red color spectrum, is consistent with the pollination syndrome of generalist passerines. The high pollination effectiveness of A. acuminatus due to the recruitment of generalist passerines as pollinators, and the specializations of floral traits to match generalist bird pollination, appear crucial in the successful colonization on islands such as Taiwan that lack specialized bird pollinators.

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Effective pollination of Aeschynanthus acuminatus (Gesneriaceae) by generalist passerines, in sunbird-absent East Asia

. Damayanti F, Garvita RV, Wawangningrum H, Rahayu S. 2021. Flower development, pollen viability and pollen storage test of Aeschynanthus radicans. Biodiversitas 22: 1940-1945. Aeschynanthus radicans Jack. commonly-known as lipstick flowers, is an epiphytic plant in Gesneriaceae family. It has an attractive morphology and is easy to grow. Therefore A. radicans is used as mother species for hybridization by plant breeders. The flowers of A. radicans are dichogamous and strongly protandrous. The pollen matures before the stigma becomes receptive and bends away and down when the stigma becomes receptive. As a thought-after material for hybridization, little is known about the flower development, pollen viability, and storability. The purpose of this study was to observe the development phase of A.radicans flowers, determine the viability of pollen during flower development, and investigate the pollen storability at -20?C. Flower development was observed in phases from small buds to anthesis. Pollen viability was tested in 10%, 15%, and 20% sucrose solution for 4 hours. Pollen storage was tested at -20?C for 77 days and tested for viability every three weeks. The best sucrose concentration for the germination of fresh pollen was 20%. The highest pollen viability was at H0 was 58±3% and gradually decreased with flowerage. The lowest viability was 18±14% at flower stage H5, coinciding with the first day of stigma receptive. Pollen storage at -20?C decreased pollen viability to 30,2±2% after 42 days and to 13,54% after 77 days.

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Flower development, pollen viability and pollen storage test of Aeschynanthus radicans

The genus Aeschynanthus Jack is revised for Singapore and Peninsular Malaysia. Four species for Singapore and fourteen species for Peninsular Malaysia are recognised, keys to the species are given, al

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D.J. Middleton

Papers

A revision of Aeschynanthus (Gesneriaceae) in Singapore and Peninsular Malaysia