Species radiations, despite immense phenotypic variation, can be difficult to resolve phylogenetically when genetic change poorly matches the rapidity of diversification. Genomic potential furnished by palaeopolyploidy, and relative roles for adaptation, random drift and hybridisation in the apportionment of genetic variation, remain poorly understood factors. Here, we study these aspects in a model radiation, Syzygium, the most species-rich tree genus worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared against a chromosome-level reference genome of the sea apple, Syzygium grande. We show that while Syzygium shares an ancient genome doubling event with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics confirms that Syzygium originated in Australia-New Guinea and diversified in multiple migrations, eastward to the Pacific and westward to India and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies. Furthermore, some sublineages demonstrate genomic clines that recapitulate cladogenetic events, suggesting that stepwise geographic speciation, a neutral process, has been important in Syzygium diversification.

The fruits of Borasseae are pyrenaria of Latania-type. This type of pericarp differentiation is also found only in Eugeissona and Nypa. The fruits of other Coryphoideae dramatically differ from Borasseae by the pericarp anatomical structure and the mode of its development.

The growth and development of Cuscuta chinensis Lam., and the effects of the holoparasite on the growth and yield of tomato (Lycopersicon esculentum), chilli (Capsicum annuum) and rice (Oryza sativa) were investigated in pot experiments under glasshouse conditions. ‘Mature’ and ‘immature’ seeds of C. chinensis showed 15 and 47% germination, respectively. The independent life duration of seedlings from ‘immature’ seeds was 6 days shorter than ‘mature’ seeds (19 days). Cuscuta chinensis formed haustoria on chilli and tomato, but not on rice seedlings. Infection with three C. chinensis seedlings per host plant reduced leaf area, dry weight, carbon and nitrogen content by 78–84% and 27–44% in tomato and chilli plants, respectively. Dry weight of C. chinensis was 0.63 g per pot in tomato, and 0.24 g per pot in chilli. Carbon and nitrogen content of C. chinensis was 0.189 and 0.028 g per pot, respectively, when grown with tomato. When it was grown with chilli, the carbon and nitrogen content of C. chinensis was 0.001 and 0.007 g per pot, respectively. Cuscuta chinensis reduced the fruit yield of tomato and chilli by 72 and 29%, respectively. The results indicated that tomato is a preferred host of C. chinensis compared with chilli, and rice is not preferred. In the host–parasite associations, C. chinensis suppressed growth and yield of chilli and tomato by diverting the elaborated products of metabolism of the hosts.

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The new hexahydroazulenones hortonones A (1) to C (3) were isolated from the leaves of three representative species of the endemic Sri Lankan genus Hortonia that belongs to the family Monimiaceae. Hortonones A (1) and B (2) have the unprecedented rearranged hortonane sesquiterpenoid carbon skeleton, and hortonone C (3) has the unprecedented rearranged and degraded 13-norhortonane skeleton. Hortonone C (3) exhibited in vitro cytotoxicity against human breast cancer MCF-7 cells at 5 μg/mL.

Abstract:In the floriculture industry of Sri Lanka, the main operations are the production of cut foliage followed by rooted cuttings and potted plants for the export market. Cut foliage species include several genera and species of flowering plants and a few species of pteridophytes. The history of collection of pteridophyte flora in Sri Lanka dates back to 1672, however at present only a few of pteridophytes are used in the domestic and international floriculture markets. Sri Lanka is blessed with a high level of diversity of pteridophyte taxa, with an enormous diversity of plant form, appearance and foliage patterns. They thrive in many habitats and are suitable to be used in the floriculture industry of the country. Several species are suggested as suitable candidates for rational domestication and use in the floriculture industry. Effective domestication of the selected pteridophyte taxa will be useful for their in situ, ex situ and circa situm conservation through utilisation.

Although Curcuma L. (Zingiberaceae) is a conserved name, with C. longa L. as its conserved type, the type of C. longa is still uncertain. Numerous discussions about the identity of the taxon called C. longa by Linnaeus have been followed by various attempts to rename turmeric, suggestions as how to settle the type and proposals to conserve the name from a later author in order to stabilize the situation. Unfortunately, none of the previous proposals can be upheld for reasons which are discussed in this article. A lectotype is selected from extant material examined by Linnaeus and an epitype collected near the type locality is designated here. The identity of C. longa is discussed and a colour plate of the species is included. Synonyms of C. longa and their types are discussed and notes on the variability of C. longa are provided.

Two new species of Anzia are described from Sri Lanka: A. mahaeliyensis characterized by a white, single-layered medulla and pale tipped isidia, and A. flavotenuis by a two-layered medulla with the upper layer yellow and the lower part white, a central chondroid axis and isidia with brown-black tips. Morphological and chemical characters used to distinguish species of Anzia are discussed and DNA sequences (ITS) are provided for the two new species. Characteristic features and worldwide distribution of the genus are also outlined.