Predictive models of aboveground plant biomass derived from nondestructive measurements greatly assist in monitoring and surveying natural areas. Where invasive species are concerned, these models can provide insights to the impacts of invasions and efficacy of management strategies. Furthermore, tools that facilitate a rapid inventory allow for multiple assessments of impact over larger areas. Downy rose myrtle [Rhodomyrtus tomentosa (Aiton) Hassk.] is an invasive shrub in Florida and Hawaii that is native to southeastern Asia. Rhodomyrtus tomentosa was imported into Florida in the early 20th century through the ornamental plant trade and produces pink flowers and edible purple globe fruits. This woody shrub is particularly problematic in the understory of Florida’s mesic pine forests, where it forms dense, impenetrable thickets. To characterize the populations more accurately in Florida and build predictive equations for biomass that could be used to inform control methods, we established a network of sites from which we harvested individuals over 3 yr. Based on these measurements, we built a simple predictive equation for R. tomentosa dry biomass. Crown area strongly associates with biomass in a linear relationship (P < 0.001, R2 = 0.82). Fruit production is highly variable, but positively correlates to plant height in individuals that have reached reproductive size (plants below 1 m generally do not produce fruit), albeit weakly (P < 0.002, R2 = 0.27). We demonstrate here that two simple measurements—height and crown area—can accurately predict biomass and, to some degree, fruit production for R. tomentosa in Florida and may guide control methods by focusing on removing individuals larger than 1 m tall.

This paper provides detailed anatomy and histochemistry of the leaves and stems of Eucalyptus tereticornis illustrated with brightfield and scanning electron microscopy. The key microscopic features that can aid in the species identification include the presence of crust-like epicuticular waxes on the leaf surfaces, platy aggregations of cluster crystals in the epidermal cells, presence of prismatic crystals in the epidermal cells, in the parenchymatous sheath in the blade and petiole, and in the cortex and pith of the stems, and leaf homogenous mesophyll consisting of palisade cells. Histochemical analyses confirmed the presence of lipophilic and phenolic compounds in the contents of secretory cavities, starch grains in the xylem parenchyma of the stem, and lignified elements in the sclerenchymatous ring adjoining the phloem and in the xylem in the leaves and stems.

The nomenclature of a number of taxa that occur in Southeast Asia in Baeckea, Decaspermum, Leptospermum, Melaleuca, Psidium, Rhodamnia, Rhodomyrtus and Tristaniopsis is discussed: eight lectotypes are designated, six taxa are shown to have been previously lectotypified under Article 9.9 with second-stage lectotypification being deemed unnecessary for two of them, and comments are made on two species that we cannot yet typify.

Eugenia stipitata occurs along rivers in Western Amazonia and produces berry-type fruits with economic potential. Its large recalcitrant (i.e. desiccation-intolerant) seeds have been proposed as a model to study seed stress response, as no apparent differentiation between the embryonic axis and the fused cotyledons are visible. Here, the longevity of submerged seeds was analysed with a view to understanding adaptive mechanisms to seasonal flooding. Submerged seeds began germinating after 2 months. After 1 year, 87 and 96% total germination was reached when seeds were submerged under a water column of 6 cm (where seedlings could emerge from under the water) and 26 cm (where seedlings could not reach the water surface), respectively. Seedling morphology was altered underwater, with short internodes and rudimentary leaf blades, and when submersion was terminated, seedlings transplanted to nursery conditions recovered a normal phenotype. Furthermore, when seedlings were detached from the seeds, the ‘resown’ seeds produced a second, normal seedling within 9 months. Concentrations of the antioxidant glutathione, which was measured as a stress marker, increased with submersion time in water. Seeds that had developed roots and shoots underwater had higher concentrations of glutathione disulphide than non-germinated seeds, suggesting that the flooding stress was more intense for seedlings than seeds, although more oxidizing cellular redox environments are also consistent with the conditions required for differentiation. Submergence underwater is recommended for storage of the recalcitrant seeds of E. stipitata for up to 1 year.

Six new species of Syzygium Gaertn. from Sumatra are described and illustrated. Three are newly described, namely Syzygium abatakum Widodo, S. bengkulense Widodo and S. ketambense Widodo. The descriptions of the other three species, namely Syzygium angustovatum Widodo & Chikmawati, S. comosum Widodo and S. longipetiolatum Widodo are republished to validate their names. The conservation status of each species is proposed, following IUCN guidelines.

This study investigated the effects of light and soil fertility, on arbuscular mycorrhizal fungi (AMF) colonization, and the growth responses (height and dry mass) of Syzygium seedlings. Seedlings of four Syzygium spp. were grown for 2 y in six different light treatments at the research station of the Sinharaja Forest, Sri Lanka. The light treatments exposed seedlings to: (1) 3%; (2) 16%; (3) 50%; (4) 100% of full sun (control); (5) short periods (2 h d−1) of direct sunlight; and (6) long periods (6 h d−1) of direct sunlight. In the 16% of full sun treatment five sets of fertilizer applications supplied: (1) magnesium; (2) potassium; (3) phosphorus; (4) all three nutrients combined; and (5) no fertilizer (control). The Syzygium species had the greatest mycorrhizal colonization in brighter treatments that provided direct light. Comparison across species revealed S. firmum to have moderate mycorrhizal colonization but high total dry mass. Syzygium operculatum had high percentages of mycorrhizal colonization while S. rubicundum had low percentages of mycorrhizal colonization especially in deep shade. Syzygium makul showed moderate levels of mycorrhizal colonization and dry mass, but low height growth. Among fertilizer applications, phosphorus enhanced seedling growth and mycorrhizal colonization for all species. However, species showed decreased growth with high amounts of potassium and combined fertilizer applications. Results suggest that AMF colonization will be highest, and Syzygium spp. growth greatest, beneath canopy openings large enough to receive direct sun in phosphorus-rich soils.

Patterns of gene flow within 21 northern Australian populations of Syzygium nervosum a dominant, mass-flowering, monsoon rain forest canopy tree were investigated using 10 isozyme loci. S. nervosum was found to have relatively high genetic diversity within populations (He = 0.307, AP = 3.7, P = 65) but also to have significantly lower frequencies of heterozygotes than expected (Ho = 0.126) and high allelic fixation (F = 0.512). Heterozygosity and allelic fixation were not correlated with measures of genetic diversity within populations, nor were they correlated with rain forest patch size, plant size or population isolation. Within populations, trees, of the same genotype (at each loci tested) were significantly clumped at short distances (c. 20 m), whereas trees of unlike genotypes were negatively associated. S. nervosum trees however, were not clonal in origin and had unique multilocus genotypes. The results suggest that the high levels of homozygosity recorded are the result of restricted pollination, primarily among flowers within individual trees or among closely related neighbouring trees, rather than rectricted seed dispersal. High homozygosity, the large fruit crop produced by trees of this species and the lack of association between heterozygosity and plant size, indicate that, S. nervosum is self-compatible, its fecundity does not appear to be impaired by inbreeding depression.

Siphoneugena Berg (Myrtaceae, Myrteae) is a small eugenioid genus with eight species ranging from Puerto Rico to Northern Argentina with the centre of diversity in Southeastern Brazil. Keys to the species and varieties are provided, as well as synonyms, descriptions, illustrations and a map of geographical occurrence. Two new taxa are described from Brazil: Siphoneugena guilfoyleiana C. Proença, the only species to occur in sandy maritime vegetation on the Ilha do Cardoso, state of São Paulo and S. densiflora Berg var. cipoensis C. Proença, an endemic of the Serra do Cipó mountain range in the state of Minas Gerais. A new combination S. dussii (Krug & Urban) C. Proença based on Marlierea dussii, is made for a species that grows in Venezuela, Guyana, Surinam and the West Indies. This study confirms current opinions as to the low taxonomic value of open versus closed calyces in establishing natural genera within the Myrtaceae.