Nothofagus, key genus of plant geography, in time and space, living and fossil, ecology and phylogeny C.G.G.J. van Steenis Rijksherbarium, Leyden, Holland Contents Summary 65 1. Introduction 66 New 2. Caledonian species 67 of and Caledonia 3. Altitudinal range Nothofagus in New Guinea New 67 Notes of 4. on distribution Nothofagus species in New Guinea 70 5. Dominance of Nothofagus 71 6. Symbionts of Nothofagus 72 7. Regeneration and germination of Nothofagus in New Guinea 73 8. Dispersal in Nothofagus and its implications for the genesis of its distribution 74 9. The South Pacific and subantarctic climate, present and past 76 10. The fossil record 78 of in time and 11. Phylogeny Nothofagus space 83 12. Bi-hemispheric ranges homologous with that of Fagoideae 89 13. Concluding theses 93 Acknowledgements 95 Bibliography 95 Postscript 97 Summary Data are given on the taxonomy and ecology of the genus. Some New Caledonian in descend the lowland. Details the distri- species grow or to are provided on bution within New Guinea. For dominance of Nothofagus, and Fagaceae in general, it is suggested that this. Some in New possibly symbionts may contribute to notes are made onregeneration and germination Guinea. A is devoted a discussion of which to be with the special chapter to dispersal appears extremely slow, implication that Nothofagus indubitably needs land for its spread, and has needed such for attaining its colossal range, encircling onwards of New Guinea the South Pacific (fossil pollen in Antarctica) to as far as southern South America. Map 1. An is other chapter devoted to response ofNothofagus to the present climate. The possibility is envisaged inthe that it could have grown along the border of the Antarctic Continent during a milder climate Creta- ceous and Tertiary. The fossil record is ample, both by macrofossils and fossil pollen. Ofthe three pollen types, the brassii and in Cretaceous in New in fusca types are already found the Upper Australia, Zealand, and Antarctica, and the in the found hitherto earlier than the Lower Table Eocene Fuegia menziesii type being not Tertiary. 1. No There it is reliable Nothofagus fossils have ever been found on the northern hemisphere. represented its with which it forms the of the Macrofossils by counterpart, Fagus, subfamily Fagoideae family Fagaceae. also from the the northern hemi- ofFagus are known from the Tertiary and possibly Upper Cretaceous (on sphere to a fairly high latitude. Map 1. called for because it the three criteria for safe Nothofagus is a key genus plant-geography meets biogeo- viz. it has sound an fossil and for which graphical reasoning, a taxonomy, ample record, diaspores long distance dispersal is excluded. a remarkable with the contraction in the Fagoideae occupy hour-glass-shaped bi-hemispheric range, Malesian Whereas the of of tropics. Map 1. evenat present largest amount morphological diversity Fagaceae 65 BLUMEA No. 66 VOL. XIX, I, 1971 in the world is found in Malesia (Lithocarpus: various sections, Quercus, Castanopsis, Trigonobalanus, and Nothofagus), with Castanea and Fagus in the Sino-Himalaya, it is likely that the cradle of Fagoideae was somewhere in the region stretching from Yunnan to Queensland. It is reasonable to assume that from this initial Cretaceous matrix in the northern and in pre-Upper Fagaceous Fagus emerged part Nothofagus for which looks the the southern part, Queensland most likely. It is shown that the evolution and of be in unforced under the spread Nothofagus can explained an way steady stateprinciple, which implicates that certain oceanic areas in the South Pacific have been land in the Cretaceous or Early Tertiary. north-south of distribution is found in the rank This bi-hemisphere pattern many groups, sometimes in sometimes in rank in of family, the lower of genus or even rare cases of species. Ranges may be almost intact the be in which almost in tropical-montane zone, as happensto Euphrasia possesses a range replicating In the transition absent. The that of Fagoideae. Map 2. others tropical relicts are very rare or even rare ones isolated and unusual are sometimes taxonomically highly interesting by being systematically showing characters. advocated that the of this of distribution have their It is tropical montanerepresentatives pattern gained series is range synchronously or almost so, as the of opportunities enabling such ranges to develop supposed to have happened only ‘once’ in geological time. This implies that taxa belonging to ‘morphologically advanced’ groups are of greater antiquity than formerly often supposed. The main conclusions have been framed in a number of theses (Chapter 13). 1. Introduction A few words of introduction for those who have no ready access to my monograph and notes (van Steenis, 1953) subsequent (van Steenis, 1953a, 1954, 1955). & southern halfof the Southern beeches range (van Steenis van Balgooy, 1966) in the 0 0 Pacific in South America from c. 33 S southwards to c. 55 S, and occur further in New Zealand, Tasmania, East Australia, New Caledonia, and New Guinea (inch the d'Entre- casteaux Islands Goodenough and Normanby, and New Britain). confined There is the leaf-shedding section Nothofagus (7 or 8 spp.) which is to South for the America except Tasmanian N. gunnii (Hk. f.) Oerst. 28 South American The evergreen section Calusparassus (c. spp.) is, 3 species excepted, confined the this the to Old World. Within section 21 Papuan—New Caledonian species 1 a that are by occupy special taxonomieposition in they characterized 2-valved cupules ) and therefore accomodated in subsection series are a special Bipartitae. This comprises a New which the Triflorae, with 4 species in New Guinea and 4 in Caledonia, in cupule others in which the contains 3 nuts, the belonging to series Uniflorae cupule has I female flower, hence I nut. who the Baumann-Bodenheim (1953), referred New Caledonian species to a separate stated that all New Caledonian have female flowers genus Trisyngyne , species 3 per cupule, but this has turned out to be an erroneous generalisation: N. aequilateralis and N. codonandra indeed have but least discoidea has female flower 3, at N. only 1 per cupule. affinities The of the species within sect. Bipartitae run, however, across the distinction of these two series showing that this systematic division is artificial and shouldbe aban- doned. the of three female flowers a of course Morphologically, presence in cupule is than of more primitive one, but this reduction has obviously taken place independently in several specific lineages. 1 related the ofthis I mention in remarkable ) Thoughnot immediately to purpose essay, want to passing a morphologicalreplica of the Fagaceous cupule in a totally unrelated plant, Blepharocarya involucrigera F. v. M., belonging to the Anacardiaceae or closely related to these. The flowers in this dioecious tree are borne in a bracteate woody involucre which according to Shaw (1966) is formed 'by the flattened, externally grooved and partly concrescentultimate branches of the inflorescence', that is, exactly as I have formerly (1953) interpreted the Fagaceous cupule. This remarkable plant is found (by coincidence?) in N. and E. Australia. C. G. G. J. van Steenis: Nothofagus 67 2. NEW CALEDONIAN SPECIES In New Caledonia at least 5 well distinct species occur; all belong to the subsect. in New Guinea. Two of these Bipartitae which otherwise only occurs show a distinct resemblance to New Guinean species, viz. N. discoidea resembles N. perryi from New Guinea and N. aequilateralis resembles N. starkenborghii from New Guinea, emphasizing the ancient plant-geographical relation between New Caledonia and New Guinea. In passing it may be said that in spite ofintentional intensive research by Professor Corner c.s. turned Solomons. on Guadalcanal at suitable height, no Nothofagus has up in the This absence from the Solomons is shared by Araucaria and Agathis. The absence of these three if of these and genera is not unexpected the very poor dispersal capacities genera the of the Solomon taken consideration. relatively young age present Is. are into See chapter 8. difference from the The New Caledonian species exhibit a remarkable vegetative Papuan species, not realized before, namely that whereas the Papuan ones have a strictly distichous phyllotaxis, the New Caledonian ones share a spiral phyllotaxis. This dualism and in phyllotaxy is, however, also found in some other Fagaceous genera though remarkable, because clearly geographical in Nothofagus, need not alarm us about the In addition I the that in generic consistency. may point to fact Vink noted that young seedlings of N. rubra the first leaves are always spirally arranged, and that distichy starts the first to occur on lateral twigs (Vink 17473). The New Caledonian species have all thick large leaves with entire or crenate margin. In New Caledonia Nothofagus shows also an ecological behaviour slightly different from that in New Guinea, viz. in altitude. ALTITUDINAL OF NOTHOFAGUS IN NEW GUINEA 3. RANGE C.A. AND NEW CALEDONIA Nothofagus was hitherto assumed to be bound to rain-forest under cold to cool climatic conditions. Accordingly it is found towards the tropics at steadily increasing altitude. — of New Guinea proper. In New Guinea, at 7° S, 98 % the collections were made between and m. 1000 3100 All species ascend to various heights above 2000 m, two excepted, viz. N. nuda and known from N. cornuta which are both only their type specimens, collected at 1200 and Six found than five 1750m respectively. species are not higher 2400 m, others occur as the sofar recorded for high as 2800—3000 m, highest locality is 3100 m N. pseudoresinosa. viz. N. Besides N. nuda, there are four species descending below 1500 m, womersleyi, N. carrii,N. starkenborghii, and N. flaviramea. The first two of these are too rarely collected idea oftheir total The latter and to gain agood range.