Phylogenetic relationships among core taxa of the paleotropical bamboo clade placed in subtribe Bambusinae, comprising Bambusa s.l. (including Bambusa s.str. and its subgenera Leleba and Lingnania) and its allies (including Dendrocalamopsis, Dendrocalamus, Gigantochloa, Melocalamus and Thyrsostachys), and with Neosinocalamus and Oxytenanthera, were examined by separate and combined cladistic analyses of the nuclear GBSSI gene and plastid psbA‐trnH, rpl32‐trnL and rps16 intron sequences using maximum parsimony and Bayesian inference analyses. The taxa were strongly supported as a monophyletic group, which represents subtribe Bambusinae. Melocalamus and Thyrsostachys were confirmed as good genera. In the combined analysis, Bambusa s.l. and Dendrocalamopsis formed one of two clades with reasonable support, and Dendrocalamus clustered with Gigantochloa, Neosinocalamus and Oxytenanthera in the other. The topology also identified several taxa that were misplaced in Bambusa or Dendrocalamus. Sinocalamus (currently a subgenus of Dendrocalamus) appeared to be heterogeneous and contained taxa allied to Bambusa or Dendrocalamus. Except for Oxytenanthera, the alliance of Bambusa and allies appeared well characterized by a broadly conical, solid and typically hairy ovary summit. The taxonomic significance of rachilla and floret characters, considered useful in distinguishing subsets of genera, remains uncertain.

Breeding system characteristics of woody bamboo species are still little known although this knowledge is important for research on genetic improvement and conservation of bamboo forests. The present study is the first report on variation in breeding system from mass and sporadically flowering bamboo populations. The results demonstrate that two Dendrocalamus species have a mixed mating system with self-compatibility, predominant outcrossing, and no agamospermy. Pollen limitation and scarcity of wild pollinators influence sexual reproduction in sporadically flowering populations of both species.

The flowering periods of woody bamboos, seed set, natural regeneration and death after flowering have been rarely observed and evaluated in the field. Dendrocalamus membranaceus Munro, a tropical woody bamboo mainly distributed in the Yunnan, displayed both sporadic as well as gregarious (mass) flowering and fruited from 2006 to 2013 following severe droughts. The aim of this study is to examine potential differences in seed set and natural regeneration between the two flowering patterns in natural D. membranaceus forests. We investigated and analyzed seed set, seed germination, seedling growth and mortality in both mass and sporadic flowering populations. Observations were made over a period of three years to record changes in bamboo seedling density, height and culm diameter. We observed a low natural seed set ranging from 1.76% to 7.49%, and a relatively high seed germination rate in the nursery from 59.6% to 71.0% for both types of flowering populations. Seeds germinated in 5–7 days after sowing and the germination period lasted 10–15 days. Seed set and germination rates in mass-flowering populations were significantly higher than those of sporadically flowering stands. The seedlings within sporadically flowering populations died within two years. In comparison, seedling mortality in the mass flowering population increased over two periods of observation from 64.92% to 98.89%, yet there was good seedling establishment left over, which showed mean height and mean culm diameter increasing by 1053.25% and 410.71%, respectively, in the second year of observations, and 137.10%, and 217.48%, respectively, in the third year. There are significant differences in seed set, natural regeneration ability and sustainability of bamboo populations between the mass flowering and sporadically flowering populations of D. membranaceus. Sporadic flowering populations failed to produce effective regeneration, while mass flowering populations were able to regenerate successfully. This study provides useful insights for conservation and natural forest management of D. membranaceus. We consider the merits of introducing other genetic provenances towards long-term maintenance of the stand features at sporadically flowering sites; meanwhile, the most economic option for mass flowering stands is to allow natural regeneration to take place through protecting such sites from further disturbance.

We assessed the variability of chloroplast DNA sequences in populations of the dipterocarp forest tree, Shorea curtisii. This species is widely distributed in hill and coastal hill dipterocarp forests of the Malay Peninsula, whereas isolated populations are found in the coastal hills of north Borneo. Two chloroplast DNA regions (1555 bp of trnH-psbA-trnK and 925 bp of trnL-trnF) were sequenced from 123 individuals collected from six Malay Peninsula and two Bornean populations. There were 15 chloroplast haplotypes derived from 16 polymorphic sites. A haplotype network revealed two distinct haplogroups that correlate with two geographic regions, the Malay Peninsula and Borneo. These two haplogroups differed by a number of mutations, and no haplotypes were shared between populations from the different geographic regions. This suggests an ancient diversification of these haplogroups, and that long-distance seed dispersal was unlikely to have occurred during the Pleistocene when the Sunda Shelf was a contiguous landmass. Phylogenetic analysis of the haplotypes together with those found in other Shorea species showed that two haplogroups in S. curtisii appear in different positions of the phylogenetic tree. This could be explained by the persistence of ancestral polymorphisms or by ancient chloroplast capture. Low levels of genetic differentiation were found between populations within each geographic region. Signature of a bottleneck followed by demographic expansion was detected in the Malay Peninsula haplogroup. The presence of two distinct evolutionary lineages in the different regions suggests that they should be managed independently to conserve the major sources of genetic diversity in S. curtisii.

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