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A re-investigation of Halle's Drepanophycus spinaeformis Göpp. from the Lower Devonian of Yunnan Province, southern China

Li, Cheng-Sen and Edwards, Dianne 1995. A re-investigation of Halle's Drepanophycus spinaeformis Göpp. from the Lower Devonian of Yunnan Province, southern China. Botanical Journal of the Linnean Society 118 (3) , pp. 163-192. 10.1111/j.1095-8339.1995.tb00468.x

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Abstract

New collections of microphyllous plants identical to those described by Halle almost 60 years ago and identified by him as Drepanophycus spinaeformis Göpp., 1852 have been made from the Emsian Xujiachong Formation, near Qujing City, eastern Yunnan Province. New information relates to orientation of leaves, epidermal and xylem anatomy, vegetative and fertile leafy shoots with roots and sporangia. The latter, dehiscing distally into two equal valves diat are elliptical to circular in face view, are attached directly to the stem by short stalks. They show no consistent relationship to leaves and are supplied by a separate vascular trace much wider than that to leaves. Detailed comparison is made with the cosmopolitan and stratigraphically long-ranging species D. spinaeformis. The Chinese specimens can be distinguished on leaf orientation, their anomocytic stomata and sporangial characters, although the latter remain conjectural in D. spinaeformis, and are therefore placed in a new species Drepanophycus qujingensis. Hypotheses relating to cooksonioids, zosterophylls and the origin of the lycopsids are reviewed and the phylogenetic position of the new taxon assessed. It is concluded that it has greatest affinity with Astewxylon mackiei, and that both exhibit the kind of fertile organization that might be anticipated in the ancestors of the lycopsids.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Q Science > QK Botany
Uncontrolled Keywords: anomocytic stomatayy; G type tracheids; Lycophytina; Zosterophyllophytina
Publisher: Linnean Society of London
ISSN: 0024-4074
Last Modified: 04 Jun 2017 02:12
URI: http://orca.cf.ac.uk/id/eprint/10842

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