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Premise of the Study: Fossilized seeds similar to Cissus (Vitaceae) have been recognized from the Miocene of Kenya, though some were previously assigned to the Menispermaceae. We undertook a comparative survey of extant African Cissus seeds to identify the fossils and consider their implications for the evolution and biogeography of Cissus and for African early Miocene paleoenvironments., Methods: Micro-computed tomography (µCT) and synchrotron-based X-ray tomographic microscopy (SRXTM) were used to study seed morphology and anatomy. Virtual taphonomy, using SRXTM data sets, produced digital fossils to elucidate seed taphonomy. Phylogenetic relationships within Cissus were reconstructed using existing and newly produced DNA sequences for African species. Paleobiology and paleoecology were inferred from African nearest living relatives., Key Results: The fossils were assigned to four new Cissus species, related to four modern clades. The fossil plants were interpreted as climbers inhabiting a mosaic of riverine woodland and forest to more open habitats. Virtual taphonomy explained how complex mineral infill processes concealed key seed features, causing the previous taxonomic misidentification. Newly sampled African species, with seeds most similar to the fossils, belong to four clades within core Cissus, two of which are early diverging., Conclusions: Virtual taphonomy, combined with X-ray imaging, has enabled recognition of the first fossil Cissus and Vitaceae from Africa. Early-divergent members of the core Cissus clade were present in Africa by at least the early Miocene, with an African origin suggested for the Cissus sciaphila clade. The fossils provide supporting evidence for mosaic paleoenvironments inhabited by early Miocene hominoids., (© 2016 Botanical Society of America.)

Premise of the Study: Recent reviews of reproductive isolation (RI) in plants propose that boundaries between closely related species are maintained predominantly through prezygotic mechanisms. However, few experimental studies have explored how boundaries are maintained in long-lived species. Hawaiian Cyrtandra presents an intriguing challenge to our understanding of RI, as it comprises 60 shrub or small tree species that are almost exclusively restricted to wet forests, where sympatry of multiple species is common., Methods: We assessed the relative strengths of pre- and postzygotic barriers among four species of Cyrtandra occurring at the extremes of the main Hawaiian Island's natural island-age gradient, Kaua'i (4.7 Myr) and Hawai'i Island (0.6 Myr), to contrast the strengths and stages of reproductive isolation among species at different stages of divergence., Key Results: A combination of F1 seed germination, F1 seedling survival, and F1 seedling growth isolated (61-91%) three of the species from sympatric relatives. In contrast, the fourth species was isolated (59%) from its sympatric relative through phenological differences alone. Significant postzygotic barriers in between-island crosses were also observed in one species., Conclusions: Results suggest that boundaries between sympatric Cyrtandra species in Hawaii are maintained predominantly through postzygotic barriers. Observations from between-island crosses indicate that postzygotic barriers can arise in allopatry, which may be important in the initial divergence of populations. Future studies of RI in Cyrtandra should include a broader range of species to determine if postzygotic isolating barriers are foremost in the maintenance of species boundaries in this large genus., (© 2015 Botanical Society of America.)

Premise of the Study: Despite the inferred Cretaceous origin of the Vitaceae, fossils of the grape family are relatively young, with the oldest previously known examples limited to the Paleocene of Europe and North America. New fossil evidence indicates that the family was already present in India in the Late Cretaceous (Maastrichtian), about 10-15 million years before the tectonic collision of India with Eurasia. •, Methods: Fruits and seeds were investigated by serial sections and peels of chert from the Deccan Intertrappean beds of central India, and compared anatomically with those of extant genera. •, Key Results: Indovitis chitaleyae gen. et sp. n. is described based on immature fruits bearing four to six seeds, and isolated mature seeds. The seeds possess paired ventral infolds and a dorsal chalaza, features diagnostic of the order Vitales. Characters of chalaza shape, infold morphology, and seed coat anatomy place I. chitaleyae within Vitaceae and favor a phylogenetic position either sister to the Vitis-Ampelocissus clade or sister to the Ampelopsis-Clematicissus-Rhoicissus clade. •, Conclusions: Presence of the oldest known vitaceous fossils in the latest Cretaceous of India indicates a previously undocumented Gondwanan history and a possible southern hemisphere origin for the Vitales. An "out-of-India" scenario might explain the relatively sudden appearance of diverse Vitaceae in the Late Paleocene and Early Eocene of the Northern Hemisphere.

Premise of the Study: The family Magnoliaceae s.l. is a basal angiosperm family with two subfamilies-Magnolioideae and Liriodendroideae, which differ by the types and structure of their fruits and seeds. The late Albian genus Archaeanthus shares many features of its reproductive organs with Magnoliaceae s.l., but its pericarp anatomy was never studied in detail. A broad-scale carpological investigation of Archaeanthus and Magnoliaceae s.l. was undertaken to reveal the nature of the similarities in fruit structure and to reconstruct Archaeanthus pericarp anatomy. These data are important to determine the early stages of fruit morphogenesis and thus to clarify relationships of Archaeanthus to the taxa of Magnoliaceae s.l., Methods: The pericarp anatomy was studied with light microscopy, SEM, and polarizing microscopy., Key Results: The dehiscent, polyspermous follicles shed from the receptacle of Archaeanthus share similarities with dehiscent follicles of Magnoliaceae s.s. and shedding nutlets of Liriodendron. The seeds of Archaeanthus are dorsiventrally flattened, ovoid, and encircled with a single circular wing. The pericarps of all the taxa studied are differentiated into exocarp (epidermis), multilayered mesocarp, and endocarp (fiber-like sclereids). The mesocarp consists of parenchyma with scattered secretory cells and sclereid clusters (Magnoliaceae s.s., Archaeanthus) or composed by sclerenchyma (Liriodendron)., Conclusions: The specializations of dehiscent multifollicles of unknown Cretaceous ancestors for different modes of seed and fruitlet dispersal formed the basis for the differentiation of two evolutionary lines with their divergence occurring more than 100 million years ago: Magnoliaceae s.s. and the Archaeanthus-Liriodendroidea-Liriodendron line (Liriodendraceae s.l.) within the order Magnoliales.

Premise of the Study: Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active role in postfire recovery of the foundation shrub Artemisia tridentata, yet conditions under which seeds persist are largely unknown., Methods: We investigated seed longevity of two Artemisia tridentata subspecies in situ by retrieving seed bags that were placed at varying depths over a 2 yr period. We also sampled naturally dispersed seeds in litter and soil immediately after seed dispersal and before flowering in subsequent seasons to estimate seed persistence., Key Results: After 24 mo, seeds buried at least 3 cm below the soil surface retained 30-40% viability whereas viability of seeds on the surface and under litter declined to 0 and < 11%, respectively. The density of naturally dispersed seeds in the seed bank was highly heterogeneous both spatially and temporally, and attrition varied significantly by region., Conclusions: Our study suggests that Artemisia tridentata has the potential to form a short-term soil seed bank that persists longer than has been commonly assumed, and that burial is necessary for seed longevity. Use of seeding techniques that promote burial of some seeds to aid in formation of a soil seed bank may increase restoration potential.