27 NATURE IN SINGAPORE 2020 13: 27–37 Date of Publication: 4 August 2020 DOI: 10.26107/NIS-2020-0004 © National University of Singapore Additions to the Flora of Singapore: New and overlooked records of exotic plant species (3) Lily M. J. Chen 1* , Hock Keong Lua 2 , Regina S. W. Yeo 3 , Le Min Choo 1 , Wei Hao Lim 1 , Parusuraman Athen 1 , Keng Soon Chua 4 , Sin Lan Koh 1 & Boon-Chuan Ho 1 1 Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, Singapore 259569, Republic of Singapore; Email: Lcmjchen@gmail.com ( * corresponding author) 2 National Biodiversity Centre, National Parks Board, 1 Cluny Road, Singapore 259569, Republic of Singapore 3 Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739- 8528, Japan 4 Lee Kong Chian Natural History Museum, National University of Singapore, Singapore 117377, Republic of Singapore Abstract. Four non-native plant species, Acalypha hispida Burm.f., Bixa orellana L., Bryophyllum tubiflorum Harv. and Calotropis gigantea (L.) W.T.Aiton from four families (Apocynaceae, Bixaceae, Crassulaceae and Euphorbiaceae), are added to the Flora of Singapore. Bixa orellana was previously overlooked as its record of naturalisation was listed in grey literature. Two genera, Bixa L. and Calotropis R.Br., and the family Bixaceae, are newly recorded for the Flora of Singapore. Key words. Asclepiadoideae, Nathaniel Cantley, casual, naturalised, new family records, new generic records, Straits Settlement reports INTRODUCTION This paper belongs to a series dealing with the naturalised and casually occurring flora of Singapore to better document its diversity with proper specimen records. 17 species have so far been added to the non-indigenous species list of Singapore in the first two parts of this series (Chen et al., 2018a; Chen et al., 2018b). In this third part, four more species, two genera, and one family are reported here for Singapore as part of this ongoing project. NEW RECORDS OF NATURALISED SINGAPORE PLANTS 1. Acalypha hispida Burm.f. Fl. Ind. 203, t. 61: f. 1 (1768) (Euphorbiaceae) (Fig. 1) Key reference. Sagun et al. (2010). Description. Shrub to c. 1.6 m tall. Leaves alternate; petiole 16.5–20.5 cm long; lamina simple, 25–28.2 × 15–19.8 cm; ovate to broadly ovate, margin serrate broadly serrate to ± crenulate, base rounded, obtuse or cuneate, apex attenuate or acuminate, pubescent/glabrous on both surfaces. Staminate inflorescences and flowers not seen (possibly dioecious). Pistillate inflorescences pendent, axillary, densely flowered, appearing bright red from the crowded mass of styles; peduncles 3.5–6.2 cm long; rachis 42.5–47 cm long. Pistillate flowers sessile; ovary c. 1 × 1 cm, ± trilobed, densely pubescent; styles 0.6–0.8 cm long, bright red, ± free at the base, laciniate. Fruits and seeds not seen. Distribution. The exact country of origin is uncertain, but it is thought to be native to the Bismarck Archipelago and Papua New Guinea (Radcliffe-Smith, 1996); it is widely cultivated elsewhere in Malesia, where it has also escaped into surrounding forests (Sagun et al., 2010). Occurrence in Singapore. This species appears to persist in abandoned areas as a remnant from former cultivation. It was previously recorded by Chong et al. (2009) as “Cultivated Only”. Local status. Casual; it is not known to set seed. This species is possibly dioecious as it is known only from cultivated pistillate plants; there are no records of the staminate plants and perfect flowers, fruits and seeds (Sagun et al., 2010). Plants are propagated exclusively from cuttings. Specimens examined. SINGAPORE: Area near Thomson Nature Park, 29 January 2020, Chen, L.M.J., Lim, W.H., Athen, P., Choo, L.M., Ho, B.C. et al., LCMJ 2020-057 (2 sheets) (SING).