Revision of the genus EndospermumBth. (Euphorbiaceae) J. Schaeffer Rijksherbarium, Leiden, Netherlands Contents Summary 171 Historical survey 172 floral Morphology(anatomy, myrmecophily, phyllotaxis, pith, leaves, glands, hairs, domatia, organs) 172 Palynological remarks (by J. Muller) 174 Infrageneric and specific delimitation 175 Affinities 176 Uses 177 Acknowledgements 177 Taxonomy 177 Index 192 Summary The revision was undertaken because the latest monograph by Pax & Hoffmann, dating from 1912, did since time has been not provide a satisfactory key, and because that a very large amountof new material collected and several new species were described. In the present revision 12 species have been recognized, among which 2 are new; 7 names have been reduced to synonymy. One (E. Pax & Hoffm.) is here for the first time excluded from the and from species eglandulosum genus Vent. the Euphorbiaceae and was found to be conspecific with Sterculia macrophylla (Sterculiaceae). The variability of the characters used by Pax & Hoffmann for infrageneric and for specific delimitation Corner appears to be far greater than formerly understood. This was already stressed by (1939) in his of the review Malayan species. For example, the peltation of leaves has appeared to be constant in not some species, but in others. The same can be said about myrmecophily — ants inhabiting hollow is in twigs — which constant 2 species, but is facultative in 2 other ones. This mild form of ‘parasitism’ is far in in encountered only from Celebes eastwards as as the Solomons (doubtful Fiji). The variability number of cells ofthe also be than the of obser- ovary appears to more complicated formerly accepted on strength vations in The in a limited number of specimens. occurrence of stellate hairs, and of indumentum general, has for Remarks this made under diadenum. The number not emerged as important taxonomy. on are E. of basal and the is variation and is in nerves the occurrence and position of glands also liable to constant a few species only. Because of the variability of characters indicated above, the affinity of the species is reticulate and does not allow the distinction of clear infrageneric taxa. A encountered is that either flowers fruits of several difficulty or species are not or inadequatelyknown that and some species are known from one specimen only. in & mentioned the of E. Though 1867 Teysmann Binnendijk occurrence polygamy in moluccanum, and and in a tree a treewith some bisexual flowers, their observation wasneveragain recorded literature. I in the material this have not been able to confirm their observation abundant of species at hand. However, I have found that E. E. two species, banghamii and ronaldii from Sumatra and the Malay Peninsula respec- flowers. Both known tively, possess bisexual are from one collection only and more material must show the constancy of this feature which is almost unique in the Euphorbiaceae; recently it has also been recorded for two species of Aporosa by Airy Shaw. In should be collecting Endospermum one always aware of the necessity to preserve specimens with flowes and/or fruit, as sterile material or specimens are very difficult to identify. It is highly desirable that observations in in on variability and polygamy are made the field or botanical gardens. 172 BLUMEA VOL. XLX, No. I, 1971 Historical survey Bentham described of the In 1861 (Fl. Hongk., p. 304) a new genus Euphorbiaceae, material Endospermum, based on collected by Champion (n. 468) and Hance (n. 1946) in The his fruit. the Hongkong. specimens at disposal were only in To generic description of the characters flowers were added, taken from anEndospermum species from Borneo. This latter material is unknown to me. Bentham classified Endospermum in the tribe Crotoneae. In 1864 Miiller Argoviensis (Flora 47, p. 469) described two new species, E. borneense and E. malaccense. Teysmann & Binnendijk (Nat. Tijd. N. I. 29, 1867, 238) based founded a new monotypic euphorbiaceous genus, Capellenia, on specimens from the Kurz Moluccas. In the same year 0- Bot. 5, p. 23) reduced Capellenia toEndospermum. Kurz of the that the main difference with the known in was opinion 3 already species was the peltate leaves of the Moluccan plant. Beccari (Malesia 2, 1884, 38) published an the nature of interesting paper on Endospermum, especially on myrmecophilous E. formi- carum Becc. He agreed with Kurz on the reduction of Capellenia. The first Philippine Lab. species recognized was E. peltatum Merr. (Publ. Gov. Philip. 35, 1905, 35). revision & Hoffmann R. In 1912 the first of.Endospermum was composed by Pax (Pfl. Heft 52, p. 33 —39). They recognized ten species, but the key to these is unsatisfactory based variable characters such leaf absence of as it is on as shape, presence or glands, nervation, hairiness, and peltate or non-peltate leaves. the tribus subtribus Pax & Hoffmann put Endospermum in Gelonieae Pax & Hoffm., the Tetrorchidiinae Pax. They divided the genus into subgenera Euendospermum Pax and & Heft first Pacific Capellenia (T. B.) Pax. In 1914 (Pfl. R. 63, p. 418) the species, E. macrophyllum (M.A.) Pax & Hoffm. was recognized, based on Macaranga macrophylla the same Merrill described a second M.A. (1866). In year (Philip. J. Sc. 9, Bot. p. 481) Philippine species, E. ovatum. the second of Hoffm. Pfl. ed. In revision Endospermum Pax & (in E. & P., Nat. Fam. 2, still classified the the tribus but referred to 19c, 1931, 184) genus in Gelonieae, now it a subtribus both and separate Endosperminae; subgenera Euendospermum Capellenia were maintained; 13 species were accepted. Merrill Arb. described from In 1934 (Contr. Arn. 8, p. 89) E. banghamii N. Sumatra. close with chinense Hoffm. He pointed out its affinity E. Benth. var. malayanum Pax & Bull. Settl. a valuable critical In 1939 Corner (Gard. Str. 10, p. 296—299) pubhshed review of the Malayan species, precursory to his Wayside Trees; in Malaya he accepted only one species. Smith described from In 1947 L. S. (Proc. Roy. Soc. Queensl. 58, p. 52) two species New Guinea, E. medullosum and E. myrmecophilum. In Shaw Bull. diadena from i960 Airy (Kew 14, p. 395) reduced Melanolepis ? Miq. the Sumatra to Endospermum as E. diadenum which appears to be correct name for E. malaccense M.A. The latest paper on Endospermum is from R. Schodde (Blumea 15, 1967, 397—402), and describing a new species from New Guinea adjacent areas, E. labios. MORPHOLOGY Anatomy. No detailed anatomical investigations have been made on Endospermum, though some attention was paid to it by several authors. Metcalfe & Chalk (Anat. the the Dicot. 2, 1950, 1207—1235, passim) put genus in Gelonieae-Endosperminae. Myrmecophily. The symbiosis of Endospermum with ants is recorded from Celebes J. Schaeffeh: Revision of the genus Endospermum Bth. (Euphorbiaceae) 173 and eastwards to the Solomon Is.; the hollow twigs of the Fijian E. macrophyllum can not be with with certainty ascribed to a regular symbiosis ants. The symbiosis is mainly confined to two species, viz. E. moluccanum and E. myrmecophi- while Like other lum, it may occur in E. medullosum. in regularly myrmecophilous plants, single specimens may have been overlooked by the ants and we have occasionally found a specimen ofE. moluccanum without hollow twigs. Also very young plants may found them not yet have acquired ants; Rant (Trop. Natuur 18, 1929, 187) already in stems of 1 cm diameter. Cultivated specimens of otherwise obhgately ant-inhabited species often lack ants and therefore solid if these from seed. keep twigs, especially specimens are grown observed does Beccari already that the specific ant, Camponotus quadriceps F. Smith, not occur west of Celebes. Besides, Rant (I.e.) observed that when ant-inhabited seedlings the the are transplanted ants soon swarm out or specific ants are easily chased away by other ants. the ant-inhabited the branches are hollow and with In specimens provided pores. The cavities used the live in. Beccari mentioned are by ants to (Malesia 2,1884, 45) already that and bitten the themselves he that the cavities pores are out by ants though believed the branches are hollow by nature. Docters van Leeuwen actually observed, however, that the of carried Hasselt pith young stems was away by ants. F. J. F. van (Trop. Natuur and stated that the hollow from the base 18, 1929, 94) Rant (ibid. p. 186—189) trees are of the the are either connected with each other or are stem up to top. The cavities they separated in internodal compartments. The advantage the ants have from the host plant is of course the provision of food(gland secretion) and housing. The advantage the host has from the ants is not so clear, but it seems certain that Endospermum has no disadvantage from the ants. From the excellent growth of trees without ants we can conclude that does need the that the Endospermum not ants, conforming to von Ihering's opinion trees need the ants as much as a dog its lice. Obligate symbiosis is apparently out of question. considered ofharmless Therefore the phenomenon may better be as some kind parasitism. The leaves are either crowded the of branches which Phyllotaxis. in apical part stout narrowed at the or distributed slender are fairly abruptly conically apex, evenly along branches which are gradually narrowed towards the apex; in E. peltatum this distinctionis valid. characters be not Though these may helpful in distinguishing the species group at first that it is make of in sight, practice learns not always easy to use them, at least not safer these characters herbarium specimens, therefore it seems not to incorporate in the key. Pith. with the be said that In connection foregoing, it can pith is always present in branches the hollow. of slender type, while the stout branches are usually Leaves.