Time series during hydration of an oriental spruce (Picea orientalis) pollen grain. Rhodamine B stains the exine (red) while fluorescein diacetate crosses plasmalemmae and indicates esterase activity in the living cells (green). Swelling of the tube cell reduces the volume of the saccate air space and results in a loss of pollen buoyancy. Confocal extended depth of focus sections taken at (top to bottom) 1, 8, and 15 min after start of hydration.
Aristolochia gigantea. Although the flowers of Aristolochia are highly specialized whereas those of Lactoris are less complex, recent phylogenetic analyses based on molecular data suggest an unexpectedly close relationship between the two genera. Stipule ontogeny and morphology are essentially the same in Piperaceae, Saururaceae, and Lactoris, while inflorescence morphology is very similar in Lactoris and Aristolochiaceae. See Gonzalez and Rudall: The questionable affinities of Lactoris: evidence from branching pattern, inflorescence morphology, and stipule development, pp. 2143-2150 in thisissue.
Scanning electron micrograph of wood of Marcgravia umbellata (Marcgraviaceae),
a lianous native of the neotropics, showing coalescent pits in the inner wall
of a vessel element (pit apertures ca. 2-3 ;gmm). Despite some characteristic
features related to the lianous habit, such as wide vessels that co-occur with
narrow vessels, axial parenchyma in proximity to vessels, and wide multiseriate
rays, the wood of Marcgraviaceae can be linked to its close relative Tetrameristaceae
About 75% of flowering plants produce calcium oxalate crystals in some or all
of their organs. Because these crystals occur in various shapes and hydration
states that are specific and consistent within each organ, they have been used
periodically as an internal taxonomic character. Since crystals and their macropatterns
are usually retained in the mature leaves and stems even after they die or drop
off the plant, such information should be useful for identification purposes,
possibly in forensics. Only a few studies have followed the development of the
crystals into what is called a macropattern in a mature organ such as a leaf.
Such a study can aid our understanding of how different crystals form and how
they relate to their specific organ tissues. Shown here are large, prismatic
crystals in cleared mesophyll cells of a pomegranate leaf, observed between
crossed polarizers. The prismatic crystal nearest the center of the image has
a central, nonpolarizing core, and two of the crystals display epitactic or
A scanning electron micrograph of a nearly mature flower of Lacandonia schismatica colorized to highlight the three central stamens (aqua), the surrounding carpels (steel blue), and styles (yellow). The six surrounding tepals are not shown. This paper is part of a larger project that in collaboration with local indigenous communities is aimed at collectively developing local capacity for documenting local flora and fauna and conservation of the Lacandon Rain Forest.
The cover was dedicated to Don Gabriel Aguilar, a scholar of Mesoamerican tropical flora, who collected thousands of plant vouchers for many important flora projects including Flora Mesoamericana and was instrumental in the discovery by Esteban Martinez and Clara Ramos of Lacandonia schismatica.
the AJB Abstract for the article: Comparative developmental series of the Mexican triurids support a euanthial
interpretation for the unusual reproductive axes of Lacandonia schismatica
by Barbara A. Ambrose, Silvia Espinosa-Matías, Sonia Vázquez-Santana,
Francisco Vergara-Silva, Esteban Martínez, Judith Márquez-Guzmán,
and Elena R. Alvarez-Buylla
Cluster of submerged buds from the water lily Brasenia schreberi at various stages of development surrounded by substantial mucilage. In the first comprehensive investigation of pollen ontogeny in Brasenia, new anatomical and ultrastructural data are used to assess the evolution of pollen characters and pollination biology among water lilies and basal angiosperms.
Air bubbles were digitally photographed as they streamed from a severed tertiary vein of a grape leaf submerged in water (inset). The camera was placed at the surface of the water. The air bubbles reveal the open, continuous xylem conduits that allow air to flow from the base of the petiole into tertiary leaf veins. Low-pressure air flow is one of the techniques used to elucidate the interconnectedness of xylem vessels across multiple organs within grapevine. Vineyardgrown Vitis vinifera cv. Cabernet Franc frames the inset.
the AJB Abstract for the article:
The structure of xylem vessels in grapevine (Vitaceae) and a possible passive mechanism for the systemic spread of bacterial disease
by Eleanor T. Thorne, Briana M. Young, Glenn M. Young, Joshua F. Stevenson, John M. Labavitch, Mark A. Matthews and Thomas L. Rost
Tyloses are shown in a tangential longitudinal view of a secondary xylem vessel
just under a wounded surface in a current-year stem of grape (Vitis vinifera
L. cv Chardonnay). Tyloses are induced outgrowths from paratracheal parenchyma
cells that block xylem vessels as a step in wound healing. The image is a bright
field digital micrograph of a section cut with a sliding microtome and stained
with safranin and fast green.
Light micrograph of the vein pattern of a New World endemic, Flaveria trinervia (Spreng.) C. Mohr., a pantropical weedy C4 species. Flaveria is of special interest because of its diversity in photosynthetic types; it has species classified as having C3, C4, or intermediate photosynthesis. This clearing of a mature leaf of F. trinervia, viewed with differential interference contrast optics, shows a reticulate pattern with high vein density and distinctive bundle sheath tissue. These two features are part of a critical suite of anatomical characteristics (Kranz anatomy) that has evolved independently many times to support C4 biochemical functioning; many variations of Kranz anatomy exist, especially in the eudicots.
Tension tissue in transverse hand section of internode 7 from unfixed wild-type
alfalfa (Medicago sativa), shown for the first time in an herbaceous
perennial using zinc chloro-iodide staining and differential interference contrast
to increase resolution of unstained cells (c. 100X). Tension tissue in angiosperms,
associated with mechanical strengthening of stems and branches to offset leaning
or other mechanical challenges, is sometimes correlated with the presence of
gelatinous fibers and/or reduced lignin content. The inner layers of the gelatinous
fibers stained dark red to purple, and the lignified outer cell walls stained
orange to yellow. Reaction phloem fibers were also identified above the reaction
xylem. The tension tissue was discovered not only in the wild type, but also
to a greater extent in alfalfa line pC3H-I with c. 64% less lignin. In addition,
tension tissue alters cell wall properties to help provide sufficient mechanical
support in the lignin downregulated line. Tension wood, however, is often viewed
as deleterious in pulp/paper and lumber manufacture; this study raises the possibility
of its increased formation in biotechnologically modified lignin-reduced woody
The tropical montane basidiolichen Dictyonema glabratum in Volcan Tenorio
National Park in Costa Rica (c. 3X actual size). The lichen symbiosis is one of
the predominant life forms in Fungi, but Basidiomycota have very few lichenized
species (e.g., in the genera Dictyonema, Lichenomphalia, and
Multiclavula), and most of them are rare and found in specific habitats.
Dictyonema glabratum is the most abundant and widespread species and
often found in large quantities on open road banks, but it is also epiphytic on
shrubs and trees. Discoveries of novel basidiolichens are rare, but a new species
of Multiclavula with a unique, previously unknown basidiocarp morphology
was discovered during the NSF-funded TICOLICHEN biodiversity inventory in Costa
The vegetative anatomy of root holoparasitic plants is difficult to interpret
because of its dramatic morphological reduction. This root holoparasitic plant,
Hydnora africana Thunb., parasitizing Euphorbia mauritanica
L. (background) in the Richtersveld of South Africa, only emerges from the soil
to flower. After the fleshy petals open, the flower emits an odor of rotting
meat to attract its pollinators, carrion flies and beetles. In anatomical investigations,
the vegetative body of Hydnora triceps Drège & Meyer was
revealed to be a rhizome with an unusual modified root-cap-like structure and
xylem characteristic of its Piperalean stock.
Leaf nectary of Prockia crucis P. Browne ex. L. (Salicaceae) with
a drop of sucrose-rich, high-energy nectar, which may be attractive to visitors.
Some species of aggressive ants get nectar from extrafloral nectaries, meanwhile
protecting the plant's leaves. This interaction may be an important strategy
to enhance the adaptive success of the species. These highly structured nectaries
are similar to the salicoids teeth of the Populus and Salix
species, lending strong support to the phylogenetic proximity of these clades.