Wang, Deming , Hao, Shougang , Xue, Jin-Zhuang .
Further study of Late Devonian sphenopsid Hamatophyton verticillatum from China.
HAMATOPHYTON verticillatum is one of the most widespread plants in Late Devonian (Famennian) of South China. Based on materials from coeval Yuelushan Formation, Yiyang District, north Hunan Province, we now reinvestigate this important plant. Its vegetative axes pseudomonopodially branch and possess ribbed internodes and nodes bearing undivided or once divided leaves. Linear leaves are in whorls. Their tips taper or slightly expand, and sometimes adaxially curve to form hook-like shape. Although H. verticillatum has been reported by many workers, knowledge of its fertile characters is still problematic. This paper shows that sporangial stalks at nodes of fertile axis lack any bracts. Each stalk is undivided, adaxially curves in distal part and terminates in a single spiny and elliptical sporangium. Stalks may occur with a fertile lateral axis at the same node of fertile main axis. This plant may represent the most primitive type in Sphenopsida and further proves the greater reproductive diversity of Sphenophyllales. Detailed anatomical study shows three-ribbed primary xylem of exarch maturation in protostele and secondary xylem lacking parenchyma cells. Anatomical comparison with other members suggests that Sphenophyllales are consistent in primary xylem architecture and moderately variable in secondary xylem structure.
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1 - Peking University, Department of Geology, Yiheyuan Road 5, Haidian District, Beijing, 100871, China
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 9:15 AM