A Jurassic flower bud from the Jurassic of China

Angiosperms may be distinguished from their gymnosperm peers by their flowers, and thus a flower is a good proxy of fossil angiosperms. However, flowers and their parts are usually too frail to be preserved in the fossil record. This makes the origin of angiosperms and their flowers the foci of controversy in botany. Eliminating such botanical controversies can only be achieved by studying related plant fossils. Applying routine SEM, LM, and MicroCT technologies, we document a fossil flower bud, Florigerminis jurassica gen. et sp. nov., from the Jurassic of Inner Mongolia, China. This fossil includes not only a leafy shoot but also physically connected fruit and flower bud. The developmentally interpolated existence of a blooming flower between the flower bud and mature fruit in Florigerminis suggests that angiosperm flowers were present in the Jurassic, in agreement with recent botanical progress. Florigerminis jurassica underscores the presence of angiosperms in the Jurassic and demands a re-thinking on angiosperm evolution.

Zingiber calcicola (Zingiberaceae), a new species from a limestone area in south Yunnan, China

Zingiber calcicola Y.H.Tan & H.B.Ding, sp. nov. (Zingiberaceae) from a limestone area in south Yunnan, China is described and illustrated here. It belongs to Zingiber sect. Dymczewiczia due to the terminal inflorescence on the leafy shoot. The description, photographs, habitat, distribution, phenology and a comparison with the allied species are also provided.

An evidence-based 3D reconstruction of Asteroxylon mackiei the most complex plant preserved from the Rhynie chert

The 407-million-year-old Rhynie chert preserves the earliest terrestrial ecosystem and informs our understanding of early life on land. However, our knowledge of the 3D structure, and development of these plants is still rudimentary. Here we used digital 3D reconstruction techniques to produce the first complete reconstruction of the lycopsid Asteroxylon mackiei, the most complex plant in the Rhynie chert. The reconstruction reveals the organisation of the three distinct axes types — leafy shoot axes, root-bearing axes and rooting axes — in the body plan. Combining this reconstruction with developmental data from fossilised meristems, we demonstrate that the A. mackiei rooting axis — a transitional lycophyte organ between the rootless ancestral state and true roots — developed from root-bearing axes by anisotomous dichotomy. Our discovery demonstrates how this unique organ developed, and highlights the value of evidence-based reconstructions for understanding the development and evolution of the first complex plants on Earth.

The influence of explants type and orientation on growth and development of Mandevilla sanderi (Hemsl.) Woodson in vitro

Mandevilla sanderi is an important commercial ornamental pot plant. Traditional vegetative propagation is limited due to the low rate, therefore there is a need to develop an alternative, more efficient method. There is an interest in development of micropropagation technology for the species, as it allows to obtain a lot of offsprings in a relatively short time. The aim of the present work was to estimate an influence of explants type and position on regeneration of Mandevilla sanderi in tissue culture. Four different types of explants (leafy shoot tips, decapitated leafy shoot tips, defoliated shoot tips, decapitated and defoliated shoot tips) were used in the experiment, which were placed on the media vertically, while defoliated shoot tips were placed horizontally or vertically upside down. The explants were cultivated on a Murashige and Skoog (MS) medium supplemented with 1 mg·dm–3 benzyladenine (BA) and 0.5 mg·dm–3 indole-3-butyric acid (IBA). It was noted that both explants orientation and positioning, influenced the multiplication rate. Defoliated shoot tips placed horizontally were characterized by higher multiplication rate (6.8) in comparison to upside down vertical positioning (3.2). It was also observed that removal of shoot apex improved axillary branching, while defoliation of shoots placed in a normal position reduced multiplication rate.

Networks of highly branched stigmarian rootlets developed on the first giant trees

Lycophyte trees, up to 50 m in height, were the tallest in the Carboniferous coal swamp forests. The similarity in their shoot and root morphology led to the hypothesis that their rooting (stigmarian) systems were modified leafy shoot systems, distinct from the roots of all other plants. Each consists of a branching main axis covered on all sides by lateral structures in a phyllotactic arrangement; unbranched microphylls developed from shoot axes, and largely unbranched stigmarian rootlets developed from rhizomorphs axes. Here, we reexamined the morphology of extinct stigmarian systems preserved as compression fossils and in coal balls from the Carboniferous period. Contrary to the long-standing view of stigmarian systems, where shoot-like rhizomorph axes developed largely unbranched, root-hairless rootlets, here we report that stigmarian rootlets were highly branched, developed at a density of ∼25,600 terminal rootlets per meter of rhizomorph, and were covered in root hairs. Furthermore, we show that this architecture is conserved among their only extant relatives, herbaceous plants in the Isoetes genus. Therefore, despite the difference in stature and the time that has elapsed, we conclude that both extant and extinct rhizomorphic lycopsids have the same rootlet system architecture.

The early fossil history of Salicaceae: a brief review

SynopsisCurrent evidence for early fossil Salicaceae is summarised. Most data come from Europe and North America where revisionary studies are in progress in several laboratories. The earliest records of the modern genera are from North America with Populus section Abaso in the Late Palaeocene and Salix subgenus Salix in the early Eocene. This evidence is based mainly on leaves but the presence of Populus is confirmed by a leafy shoot with attached fruiting raceme. The two genera first occur later in Europe with Populus in the uppermost Eocene and Salix in the Middle Oligocene. Members of both genera in both continents apparently occupied riparian habitats early in their history.