2017/11/01 by Zhuo Feng, Yong Lv, Yun Guo +2 · 2 citations
Agricultural and Biological Sciences · #Botany and Geology in Latin America and Caribbean #Plant Diversity and Evolution #Fern and Epiphyte Biology
paper · pdf · doi:10.1098/rsbl.2017.0456
openalex publication_date 2017/11/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Today, cycads are a small group of gymnospermous plants with a limited distribution in the (sub)tropics, but they were major constituents of Mesozoic floras. Fossil leaves sporadically found in latest Carboniferous and Permian floras have putatively been ascribed to cycads. However, their true affinity remains unclear due to the lack of anatomical evidence. Virtually all modern cycads have pinnate leaves, but this type of leaf morphology is by no means unique for cycads. Pinnate leaves of Plagiozamites oblongifolius Halle 1927 with well-preserved cuticles showing the epidermal anatomy are here described from the upper Permian Xuanwei Formation of Yunnan Province, Southwest China. The cuticles show a clear differentiation into costal and intercostal zones; stomata are confined to the intercostal zones on both the upper and lower leaf surfaces. The external morphology and the epidermal anatomy of these fossil leaves are closely comparable with those of extant cycads, particularly members of the family Zamiaceae.