Gardens'BulletinSingapore56(2004) 95-100. 95 Begonia sizemoreae Kiew (Begoniaceae), a Handsome New Begonia from Vietnam RUTH KIEW Singapore Botanic Gardens, Singapore 259569 Abstract Begonia sizemoreae Kiew (sect. Platycentrum) is describedfromthe BaVi NationalParkin NorthVietnam. CloselyrelatedtoB. rexPutzeys andwith similarlyfinevariegated leaves, it is strikingforthecrimsonreticulationofveins inthecentralandmarginalpartsoftheleaves. Introduction ThisattractivebegoniawasfirstdiscoveredbyMarySizemoreon6thNovember 1996 in BaVi National Park. c. 80 km westofHanoi, Vietnam. Itwas listedin the American Begonia Society's Unidentified Species List as Begonia U388 and, because of its beautiful leaves, was quite widely circulated among the Society's members (Keepin, 2003). Naming such a striking plant, which is a significant addition to the foliage begonias already in cultivation, is long overdue. It is here described and illustrated and is named in honour ofMary Sizemore. Begonia sizemoreae Kiew, sp. nov. A Begonia rege Putzeys petiolis quam laminis subduplo longioribus, venis tertiariisfoliorumrubrisetcymis 3-floris statimdignoscenda. Typus: Vietnam, BaVi National Park, HaTay Province, c. 80 km westofHanoi, Accession No. 20020399cult,inSingaporeBotanicGardensex PalmHammockOrchidEstate, Miami, U.S.A. R. Kiew 5304 (holo SING, iso HN). Plate 1 Begoniarhizomatous. Stem creeping, not branched, succulent, c. 2.5 cm long mm andc. 5 thick; reddish brown orpurplish; withoutatuber. Indumentum of mm white, c. 10 long, uniseriate hairs, scattered on the upper lamina surface mm (not on the veins), these c. 5 long and dense on the stem, stipules and mm petiole, 2-4 long anddense on thelaminamargin andon the undersurface 96 Gardens'BulletinSingapore56(2004/ of the midrib, secondary and tertiary veins. Stipules persistent, broadly triangular tapering to a setose point, 8-12 x 4-9 mm, reddish when young, becoming pale yellowish green with a reddish band along the midrib, margin entire. Leaves alternate, tufted;petiole terete, (4.5-)10.5-19 cm long, pale red or purplish; lamina oblique, asymmetric, broadly ovate, 6.5-11.5 x 5.5-10.5 cm. broad side 4-6.5 cm wide, base unequallycordate, largerbasal lobe 2.25- 3.5 cm long, margin entire, slightly undulate, apex slightly acute, sometimes rounded, lamina slightly velvety above and thinly succulent in life, papery when dried, variegated on the upper surface with the basal part (less than half mm the lamina width) and abandc. 10-15 wide around the marginjade green sometimes with a blackish hue and with the middle part pale silvery grey- green, secondary veins green in the basal part, white in the middle part and deep crimson in the marginal band, tertiary veins deep crimson in the basal and marginal parts and white in the middle part, on the lower lamina surface green with secondary veins greenish brown, tertiary veins deep crimson; venation palmate-pinnate with 2 pairs of secondary veins at the base and 2 pairs along the midrib with another vein in the basal lobe, secondary veins branching c. halfway to the margin, impressed above, prominent beneath. Inflorescencesaxillary, monochasialcymes,protandrouswithtwomaleflowers and one female flower, glabrous, 7.25-19.5 cm tall with two branches 2-3 mmlong, rosy red, greenish distally. Bracts narrowly ovate, 11-15 x4-5 mm. glabrous, pale green, almosttransparent, reddish along themidrib andtowards the tip, apex acutely pointed, margin entire, caducous. Maleflower, pedicel mm 18-20 long, pale pink or white; tepals 4, glabrous, margin entire, apex rounded, outer two tepals ovate, 18-25 x 13-14 mm, deep pink paler towards base, longitudinal veins slightly impressed; inner two tepals oval, 16-25 x 9- 11 mm, pale pink, veins not impressed; stamens many, joined into a more or less globose cluster, 5-7 x 5 mm; filamentsjoined into acolumn for 1-3.5 mm andfree forc. 1.25 mm, white; anthers narrowly oblong, c. 2.5 mm long, deep mm yellow, apex strongly apiculate, c. 1 long, thecae dehiscing throughlateral mm slits.Femaleflower: pedicel 15-25 long, slightlyreddish; ovarypalegreen, mm 7-8 x 20-23 mm, wings 3, unequal, long wing 12-17 wide, two shorter mm wings 3-5 wide, locules 2, placentas bifid; tepals 5. obovate taperedto an acute apex, more or less isomoiphic, 19-21 x 10-12 mm, deep pink at the tip. paler at the base, margin entire and undulate; styles and stigma golden yellow mm mm or yellowish green, styles 2, 8-9 long, joined for c. 2 at the base, bifurcating in the upper third; stigmas a spiral papillose band. Fruit and seed not known. Distribution: Endemic in N. Vietnam (Ba Vi National Park). Habitat: Locally common on earth banks beside the road in medium shade at m c. 800 altitude. BegoniasizemoreaefromVietnam 97 Plate 1. Begonia sizemoreae Kiew. A. The plant. B. Monochasial cyme with two male flowers and the developing female flower. C, D. Male flower. E, F. Female flower. Serena Lee 98 Gardens'BulletinSingapore56(2004) Other specimen examined: U.S.A., Palm Hammock Orchid Estate, Miami, Kiew s.n. 10 Feb 2002 (SING). Notes: Begoniasizemoreaebelongsto sect. Platycentruminbeingrhizomatous, protandrous, and having a male flower with four tepals and a female flower with an ovary with one wing much longer than the other two, two styles, and two locules each with a bifid placenta. This new species is very similar to Begonia rex Putzeys from Assam, India, in its leaf shape, the silvery band around the middle of the leaf and in flower structure. However, B. sizemoreae is distinct in its petioles being much longer(over 1.5 times longer) thanthelaminaanddensely hairy, whereas inB. rexthe petioles are shorterthan the lamina and are less hairy. The lamina ofB. rex is distinctly bullate, while that ofB. sizemoreae is not. The details ofthe variegation are significantly different: inB. sizemoreae thebasal and marginal parts ofthe lamina arejade green with striking deep crimson venation, while in B. rex the basal and marginal parts are dark green to bronzy green and the venation is concolorous. In addition, the leafbase is never overlapping, as is seen in wild collections ofB. rex (e.g. Griffith 2588, K). InB. sizemoreae, the inflorescence is a three-flowered, monochasial cyme with a single female flower, while in B. rex it is a dichasial cyme with four female flowers. TheintroductionofBegoniarexiswell documented-itwas inadvertently introducedfromAssamtogetherwithaconsignmentoforchids andwasbought by J. Linden for 10,000 francs (Thompson & Thompson, 1981). The original Frenchpublicationdescribeditas 'cemerveilleBegonia'(Hooker, 1859). Since then it has been hybridized with a wide range of species, both closely and distantly related, to produce an amazing variety of leaf shapes (some even spiral!), colours, patterns and leaf textures but most with the characteristic silvery sheen. It is doubtful now whether any 'pure'/?, rex plants exist in cultivation considering the ease with which it hybridizes. As Krempin (1993) records, the hybrids ofB. rex are 'never ending' and there are probably more than a thousand named and unnamed. Begonia rex is not recorded wild from Vietnam. Ho (1991, 1999) included it in his account ofVietnamese begonias as a cultivated species. Golding(2004)recently identifiedBegoniaU388, whichisheredescribed as Begonia sizemoreae, as B. longiciliata C.Y. Wu, a begonia from Guizhou, China. However, B. sizemoreae is different from this species in its variegated leaves, the larger basal lobe (one third as long as the midrib) and the entire margin; the inflorescence is a monochasial cyme with two much larger male flowers. In contrast, the lamina of B. longiciliata is plain deep green above and green beneath, the larger basal lobe is only one fifth to one sixth as long as the midrib, and the margins are denticulate; the outer tepals of the male flowers are 13 by 8 mm and the inner ones 9 by 3.5 mm. Although Wu in Wu Begoniasizemoreaefrom Vietnam 99 & Ku (1995) described the inflorescence as monochasial with two flowers, the illustration shows it to be dichasial with potentially six male flower and four fruits. In this latter character, it resembles B. rex. Apart from its stunning foliage, Begonia sizemoreae has the advantage that itis easy to grow in cultivation unlike many other wild species inAsia. In cultivation, itsleavescangrowupto26by 16.5 cm(M. Sizemore,/?<?rs. comm.). Itflowers freely and, in Singapore, itisnot seasonal. Itpropagates easily from the leaves. Keepin (2003)reports thatitis selfcompatible andproduces viable seed. This new species is therefore an important addition to the stable of cultivated begonias. Its charm lies in the deep crimson tracery of the fine network ofveins-a feature not seen in B. rex. No doubt, it too will prove easy to hybridise, but it is important to keep a pure line so that its identity is not lost. Acknowledgements I am grateful to Mary Sizemore who shared her discovery with other begonia enthusiasts and who provided habitat data; to the Institute of Ecology and Biological Research (NCST), Hanoi, Vietnam for giving M. Sizemore permission to collect plants and to Nguyen Van Du, who accompanied her; to TimAnderson, Palm Hammock Orchid Estate, who drew my attention to this species andprovidedme withmaterial; toNorhayati MohdDin, forhercare of the Singapore Botanic Gardens begonia collection; to Serena Lee for the photographs; to M.J.E. Coode for correcting the botanical Latin; and to the Keeper of the Herbarium, Royal Botanic Gardens Kew, for permission to examine specimens in his care. References Golding, J. 2004. Begonia U 388 is Begonia longiciliata C.Y.Wu. The Begonian. 71: 154- 156. Ho, P. H. 1991. Figure 2053 Begonia rex. Cay Co VietNam. 1: 739. Ho, P. H. 1999. Figure 2339. Begonia rex. Cay CS VietNam. 1: 585. Hooker, W. J. 1859. Begonia rex, Royal Begonia. Curtis's Botanical Magazine. 85: Plate 5101. Keepin, T. 2003. BegoniaU388 outofa terrarium in Houston. TheBegonian. pg. 128. Krempin, J. 1993. Know YourBegonias. Krempin Book,Australia. 100 Gardens'BulletinSingapore56(2004) Thompson, M.L. andEJ. Thompson. 1981. Begonia-The CompleteReference Guide. Times Books, U.S.A. Wu, C.Y. and T.C. Ku. 1995. New taxa ofthe Begonia L. (Begoniaceae) from China. Acta Phytotaxonica Simca. 33: 251-280. Note added in press: A begonia called 'Vietnamese hairy Begonia was illustratedin TheGarden(2004)Volume 129 (7): 515, afterithadbeenexhibited at the Chelsea Flower Show. From the photograph, it looks very like Begonia sizemoreae, which suggests that this species is beginning to enter the horticultural trade.