Positive pressure in bamboo is generated in stems and rhizomes, not in roots.

Bamboos stand out among other tall plants in being able to generate positive pressure in the xylem at night, pushing water up to the leaves and causing drops to fall from leaf tips as guttation that can amount to a steady nocturnal 'bamboo rain'. The location and mechanism of nocturnal pressure generation in bamboos are unknown, as are the benefits for the plants. We conducted a study on the tall tropical bamboo species (giant timber bamboo) growing outdoors in southern California under full irrigation to determine where in the plant the nocturnal pressure is generated, when it rises in the evening, and when it dissipates in the morning.

Do seedlings of larger geophytic species outperform smaller ones when challenged by drought?

Premise: In semiarid regions, decreasing rainfall presents a challenge to perennial seedlings that must reach sufficient size to survive the first year's seasonal drought. Attaining a large storage organ size has been hypothesized to enhance drought resilience in geophytes, but building larger storage organs requires faster growth, but paradoxically, some traits that confer faster growth are highly sensitive to drought. We examined whether tuber size confers greater drought resilience in seedlings of four closely related geophytic species of Pelargonium.

Lipids in xylem sap of woody plants across the angiosperm phylogeny.

Lipids have been observed attached to lumen-facing surfaces of mature xylem conduits of several plant species, but there has been little research on their functions or effects on water transport, and only one lipidomic study of the xylem apoplast. Therefore, we conducted lipidomic analyses of xylem sap from woody stems of seven plants representing six major angiosperm clades, including basal magnoliids, monocots and eudicots, to characterize and quantify phospholipids, galactolipids and sulfolipids in sap using mass spectrometry. Locations of lipids in vessels of Laurus nobilis were imaged using transmission electron microscopy and confocal microscopy.

Leaf margins in a deciduous lineage from the Greater Cape Floristic Region track climate in unexpected directions.

Premise: The functional significance of leaf margins has long been debated. In this study, we explore influences of climate, leaf lobing, woodiness, and shared evolutionary history on two leaf margin traits within the genus Pelargonium.

Methods: Leaves from 454 populations of Pelargonium (161 species) were collected in the Greater Cape Floristic Region and scored for tooth presence/absence and degree of lobing.

Divergent trait and environment relationships among parallel radiations in Pelargonium (Geraniaceae): a role for evolutionary legacy?

Functional traits in closely related lineages are expected to vary similarly along common environmental gradients as a result of shared evolutionary and biogeographic history, or legacy effects, and as a result of biophysical tradeoffs in construction. We test these predictions in Pelargonium, a relatively recent evolutionary radiation. Bayesian phylogenetic mixed effects models assessed, at the subclade level, associations between plant height, leaf area, leaf nitrogen content and leaf mass per area (LMA), and five environmental variables capturing temperature and rainfall gradients across the Greater Cape Floristic Region of South Africa.

Functional Traits in Parallel Evolutionary Radiations and Trait-Environment Associations in the Cape Floristic Region of South Africa.

Evolutionary radiations with extreme levels of diversity present a unique opportunity to study the role of the environment in plant evolution. If environmental adaptation played an important role in such radiations, we expect to find associations between functional traits and key climatic variables. Similar trait-environment associations across clades may reflect common responses, while contradictory associations may suggest lineage-specific adaptations.

Phylogenetic influences on leaf trait integration in Pelargonium (Geraniaceae): convergence, divergence, and historical adaptation to a rapidly changing climate.

Premise Of The Study: Trait integration may improve prediction of species and lineage responses to future climate change more than individual traits alone, particularly when analyses incorporate effects of phylogenetic relationships. The South African genus Pelargonium contains divergent major clades that have radiated along the same seasonal aridity gradient, presenting the opportunity to ask whether patterns of evolution in mean leaf trait values are achieved through the same set of coordinated changes among traits in each clade.

Methods: Seven leaf traits were measured on field-collected leaves from one-third of the species (98) of the genus.