Cross-sectioning to the core of conifers: pith anatomy of living Araucariaceae and Podocarpaceae, with comparisons to fossil pith

What is it about?

Despite all the hype about dinosaurs, there is still relatively little known about the ancient plants that nourished them and created the habitats in which they lived. The first step in understanding the Jurassic vegetation is to collect fossil plants and identify them. The most common plant fossil is wood, and we can use the cellular structures in wood to identify the ancient forest trees. One of the most poorly studied tissues in wood, even in living trees, is located in the very center of the stem and is called pith. Thus, a study of pith in living conifers can serve as the basis for understanding Jurassic conifer wood with pith. To this end, we have undertaken a study of pith in living conifers in two families that once dominated the Jurassic, the Araucariaceae (which include monkey puzzle trees) and Podocarpaceae (which include yellowwoods and Buddhist pine). The branches of 7 genera and 16 species were collected from botanical gardens, sectioned in the lab, stained with color, and their pith was studied with a light microscope. It turns out that there is a diversity of different kinds of cells that form patterns in the pith of each species. Even the shape of the pith, when cut cross-wise, can be quite distinctive. Not only has our study filled a huge gap in plant anatomy, we also hope that it will serve as a basis to identify conifer trees in future paleobotanical studies on fossil wood.

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