4/15/2023 0 Comments Metasequoia uv mappingAlso included are brief summaries of the expeditions that obtained the five collections, as well as a short account of earlier botanical collections from Central China, a description of the salient features of the metasequoia flora, an analysis of the gymnosperms that occur with metasequoia, and my interpretation of the metasequoia flora. glyptostroboides was later discovered growing in a 'natural population (see below). While the type locality of Metasequoia glyptostroboides is in eastern Szechwan, the specimens on which this work is based are from the general area (here referred to as the "metasequoia area") in Hupeh Province where M. A systematic enumeration of all identifiable species represented in the five collections (an assemblage of species here termed the "metasequoia flora") is presented below. In 1973 this herbarium material was turned over to me for identification, and this article is concerned with the information resulting from that undertaking. In addition to the seed, five shipments of herbarium specimens collected in southwestern Hupeh Province between 19 were received at the Arnold Arboretum by the late Professor Elmer D. glyptostroboides that had been collected during the summer of 1948. ![]() Cheng concerning the shipment was later placed with the unmounted specimens of M. These seeds, mailed from Nanking, China, on November 29, 1948, and totaling 500 grams, were the second shipment received at the Arnold Arboretum. At that time help was needed to place fresh, recently imported metasequoia seed into small envelopes for distribution to botanical institutions, forest experiment stations, and interested individuals around the world. ![]() MY FIRST ASSOCIATION with Metasequoia glyptostroboides Hu & Cheng was at the Arnold Arboretum of Harvard University during the winter of 1948-1949. The Metasequoia Flora and Its Phytogeographic Significance Thus, interpretations of physiological and environmental signals from conifer leaves in Lagerstätten are not likely impacted by early diagenesis.THE METASEQUOIA FLORA AND ITS PHYTOGEOGRAPHIC SIGNIFICANCE Together, these findings suggest that: 1) rapid burial and tissue stabilization is essential in the formation of Lagerstätte fossils, 2) polysaccharides play a key role in maintaining three-dimensional fossil leaf structures and thus polysaccharide preservation implies rapid burial and minimal microbial degradation, and 3) carbon isotope signals, including at the molecular level, altered little during diagenesis. Despite morphological and molecular changes, the stable carbon isotopic composition of bulk leaves and n-alkanes remained virtually unchanged. Both decay series demonstrate that microbial degradation of polysaccharides occurs on extremely short timescales and results in cell collapse, first in the exclusively cellulose-based primary cell walls and then much later in the lignin -strengthened secondary cell walls. ![]() Both experiments used modern leaves of the dawn redwood Metasequoia glyptostroboides, referred to as a “living fossil” due to the morphological stability of the genus Metasequoia over the past 100 million years. ![]() To better understand molecular, isotopic, and morphological changes during the early stages of diagenesis, degradation experiments were conducted in two time series: 1) a laboratory decay series using fungi on leaves over the course of a month and 2) a natural decay series with leaves collected from different stages of leaf senescence and early diagenesis. Sedimentary deposits yielding extraordinarily-preserved fossils (known as Lagerstätten) may provide significant insights into the physiology and environments of ancient plants, particularly when the fossils represent their original characteristics with limited diagenetic modifications.
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