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• Premise of the study: Few studies have analyzed the physiological performance of different life stages and the expression of ontogenetic niche shifts in lianas. Here, we analyzed the photosynthetic and morphological acclimation of seedlings of Stigmaphyllon lindenianum, Combretum fruticosum, and Bonamia trichantha to distinctive light conditions in a tropical dry forest and compared their response with the acclimation response of adult canopy lianas of the same species. We expected acclimation to occur faster through changes in leaf photochemistry relative to adaptation in morphology, consistent with the life history strategies of these lianas.• Methods: Seedlings were assigned to the following light treatments: high light (HH), low light (LL), sun to shade (HL), and shade to sun (LH) in a common garden. After 40 d, HL and LH seedlings were exposed to opposite light treatments. Light response curves, the maximum photosynthetic rate in the field (Amax), and biomass allocation were monitored for another 40 d on leaves expanded before transfer.• Key results: Photosynthetic responses, Amax, and biomass of Stigmaphyllon and Combretum varied with light availability. Physiological characters were affected by current light environment. The previous light environment (carryover effects) only influenced Amax. Morphological characters showed significant carryover effects. Stigmaphyllon showed high morphological and physiological plasticity. Sun-exposed seedlings of this liana increased stem biomass and switched from self-supporting to climbing forms.• Conclusions: Acclimation in seedlings of these lianas is consistent with the response of adult lianas in the canopy in direction, but not in magnitude. There was no evidence for ontogenetic niche shifts in the acclimation response.

Phloem is one of the vital tissues of the vascular system that plays a crucial role in the conduction of photosynthates. In vascular plants, it develops external to the vascular cambium but in a small fraction of eudicots (formerly known as dicots), it occurs within (interxylary) and inside (intraxylary) the secondary xylem. Ontogenetically, it is classified as Strychnos, Combretum, Azima, and Calycopteris types. In all four cases, phloem islands remain enclosed within the secondary xylem but each has unique origins. Similarly, the deposition of the phloem at the pith margin is common in several plants. It develops from procambial derivatives or adjacent pith cells or by initiating an intraxylary phloem cambium. Functionally, this cambium can produce only phloem or both secondary xylem and phloem. In some instances, the deposition of the secondary xylem and phloem in the same direction has also been documented. Some experimental evidence is available on the role of phloem but is it applicable to inter- and intraxylary phloem? The presence of inter- and intraxylary phloem is attributed to a defence mechanism against insects or plants that show sudden and enormous flowering or it can correlate with high temperatures or an unconducive climate in a desert region where sieve tube elements have become nonfunctional due to high temperatures. The present review is an attempt to analyse the role of interxylary and intraxylary phloem.

Tree species diversity and distribution in forests, agroforests and other land uses have been continuously providing food and food-associated materials, medicinal, and livestock fodder, as well as multiple ecological services to human beings. However, unsustainable utilization of forest resources coupled with biotic and abiotic disturbances interrupt forest resources sustainability and ecological processes. A study was conducted in Abu Gadaf Natural Forest Reserve (AGNFR) in 2018 to assess the current status of tree species diversity and use, by surveying 554 sample circular plots (each having 35.7 m radius) with 0.5% sampling intensity distributed systematically throughout the reserve. We found a total of 32 tree species in the AGNFR that belonged to 16 families. The highest tree species frequency, occurrences and density recorded by Combretum hartmannianum followed by Lannea fruticosa and Anogeissus leiocarpus respectively. The highest Importance Value Index (IVI) was recorded by Combretum hartmannianum (51.28). The highest DBH of trees were reported in the range of 10–19.9 cm followed by 20–29.9 cm, additionally the Shannon diversity index and Simpson dominance index were 1.01 and 0.14, respectively and density was 48 tree/ha. Majority of the tree species was found unsustainably harvested affecting their regeneration potential. Different kinds of anthropogenic disturbances including forest fires were rampant in the reserve causing dwindling tree diversity. The study provides baseline information on tree species diversity, and distribution pattern for effective management and conservation of the forest reserve. A preservation action plan may be needed immediately to protect the vulnerable species, particularly those with high ecosystem service value.

A systematic treatment of the native Combretaceae in the Indo-Burmese region, including Sri Lanka, India, Pakistan, Nepal, Bhutan, Bangladesh and Myanmar, is presented in a synoptic way. Four genera, 50 species and seven varieties are recognized and treated with keys to the genera and species, nomenclature, relevant synonymy, typifications, habitat, and distribution. A total of 22 names have been lectotypified, including second-step lectotypes for two names. Neotypes are designated here for 11 names and an epitype for one name. New varietal combinations have also been proposed for three names, namely Terminalia coronata var. parviflora , T. pendula var. fischeri , and T. pendula var. phillyreifolia .

Key message Most effects of environmental variables on growth, wood stiffness, specific stiffness and density, and correlations between growth and wood stiffness, specific stiffness and density were not consistent among species. Wood stiffness is a key functional trait of woody plants, but variation in wood stiffness has not been studied in native tree and shrub species in Africa. We investigated variation in growth (height, stem diameter, height/diameter ratio, ring width), wood stiffness (dynamic modulus of elasticity in longitudinal and tangential axes), specific wood stiffness (dynamic modulus of elasticity divided by air-dry density) and air-dry density of Balanites aegyptiaca , Combretum glutinosum , Guiera senegalensis , Piliostigma reticulatum and Ziziphus mauritiana related to region, land use type, soil type, terrain type, latitude, longitude, elevation and mean annual rainfall, and correlations of growth with wood stiffness, specific wood stiffness and wood density in the Sahelian and Sudanian ecozones of Mali. Growth variables, wood stiffness and wood density differed significantly among some of the species, but specific wood stiffness did not differ significantly among any of the species. There were few consistent effects of the environmental variables on growth and wood variables of the five species. Geographical coordinates generally had stronger effects than mean annual rainfall on growth and wood variables of the species. Positive correlations between growth and wood density were significant in three of the species. Correlations between height and wood stiffness and/or specific wood stiffness differed in sign among some of the species. Results illustrate that different species may respond differently to environmental factors in the Sahelian and Sudanian ecozones of West Africa.

This paper reports the results of a study on the morphology, mode of secretion, ultrastructure and histochemistry of leaf secretory scales of Combretum molle using both light and electron microscopy. The density of the secretory scales is higher on the abaxial leaf surface in the intervein areas. Each secretory scale is made up of a basal epidermal cell, a short bicellular stalk and a multicellular umbrella-like head comprising 8–24 cells. The secretion is released from each head cell into the subcuticular space through a lateral ostiole, and then onto the leaf surface via a central pore on each scale. This secretion mechanism is described in this study for the first time in family Combretaceae. Ultrastructural characteristics of scale cells display the typically active metabolism of secretory systems. Preliminary histochemical investigations show that these scales contain lipids, terpenoids, phenolics, flavonoids and alkaloids which probably offer anti-microbial and anti-herbivore protection.