The stem ofPachypteris papillosa(Thomas&Bose) Harris
作者:
TOM M. HARRIS,
期刊:
Botanical Journal of the Linnean Society
(WILEY Available online 1983)
卷期:
Volume 86,
issue 1‐2
页码: 149-159
ISSN:0024-4074
年代: 1983
DOI:10.1111/j.1095-8339.1983.tb00722.x
出版商: Blackwell Publishing Ltd
关键词: Mesozoic pteridosperm;Pachypteris stem
数据来源: WILEY
摘要:
Pachypteris papulosa(Thomas&Bose) Harris, leaves of a pteridosperm, are locally abundant in the Middle Jurassic of Yorkshire. Microsporophylls too are known but the stem has been represented only by a few puzzling fragments. Better‐preserved stem material is now described. When young the stems were thick (up to 15 mm) and largely composed of soft parenchyma and thus succulent. The leaves are borne sparsely, each at the end of a prominent mamilla. The stem surface is covered by hemispherical emergences with a thickly cutinized epidermis which, when isolated, are beret‐shaped. This cuticle is the only robust part of the young stem.Later the stem formed a thick cylinder of wood and the surface was stretched. A new surface i presumed to be cork), was formed and the ‘berets’ and mamillac were lost. Branching occurs at distant intervals, when the stem divides nearly equally into widely diverging parts.Pachypteris papillosais pictured as a large shrub forming a mangrove‐like thicket along tid
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