The stomatal density of the Quercus delavayi complex may be a useful proxy for reconstruction of paleo-CO2 concentrations.

Photo credit: Google

Quercus delavayi

Evolution of stomatal and trichome density of the Quercus delavayi complex since the late Miocene.

by Hu Q., Xing Y. W., Hu J. J., Huang Y. J., Ma H. J., Zhou Z. K. (2013)

  • Qian Hu, Key Laboratory of Biogeography and Biodiversity, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
  • Yaowu Xing, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, 666303, China
  • Jinjin Hu, Key Laboratory of Biogeography and Biodiversity, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
  • Yongjiang Huang, Key Laboratory of Biogeography and Biodiversity, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
  • Hongjie Ma, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming, 650093, China 
  • Zhekun Zhou, Key Laboratory of Biogeography and Biodiversity, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China

in Chin Sci Bull, 2013, 58, doi: 10.1007/s11434-013-6005-x –

https://link.springer.com/article/10.1007/s11434-013-0038-z

Screen Shot 2017-09-15 at 11.52.21
Photo credit Researchgate – Quercus tenuipilosa – https://www.researchgate.net/profile/Yaowu_Xing/publication/255892023/figure/fig3/AS:341212864237570@1458362894121/Fig-5-Cuticular-structures-of-Quercus-tenuipilosa-sp-nov-and-Q-delavayi-under-the.png

Fig. 5 Cuticular structures of Quercus tenuipilosa sp. nov. and Q. delavayi under the light microscope. a Adaxial epidermis of Q. tenuipilosa. Holotype. Slide No. HST856-20120814-upper-01. Scale bar 50 lm. b Adaxial epidermis of Q. delavayi. Slide No. DH030- 3A-1. Scale bar 50 lm. c Abaxial epidermis of Q. tenuipilosa. Holotype. Slide No. HST856-20120814-lower-01. Scale bar 50 lm. d Abaxial epidermis of Q. delavayi. Slide No. DH030-4A-2. Scale bar 50 lm. e Anomocytic stomata of Q. tenuipilosa. Scale bar 10 lm. f Anomocytic stomata of Q. delavayi. Slide No. DH030-4A-2. Scale bar 10 lm. g Multicellular trichome base of Q. tenuipilosa. Slide No. HST856-20120814-lower-01. Scale bar 10 lm. h Multicellular trichome base of Q. delavayi. Slide No. DH030-4A-2. Scale bar 10 lm  

Abstract

A fossil oak species, Quercus tenuipilosa Q. Hu et Z.K. Zhou, is reported from the upper Pliocene Ciying Formation in Kunming, Yunnan Province, southwestern China.

The establishment of this species is based on detailed morphologic and cuticular investigations. The fossil leaves are elliptic, with serrate margins on the apical half. The primary venation is pinnate, and the major secondary venation is craspedodromous. The tertiary veins are opposite or alternate-opposite percurrent with two branches.

The stomata are anomocytic, occurring only on the abaxial epidermis.

The trichome bases are unicellular or multicellular. The new fossil species shows the closest affinity with the extant Q. delavayi and the late Miocene Q. praedelavayi Y.W. Xing et Z.K. Zhou from the Xiaolongtan Formation of the Yunnan Province.

All three species share similar leaf morphology, but differ with respect to trichome base and stomatal densitiesQ. tenuipilosaQ. praedelavayi, and Q. delavayi can be considered to constitute the Q. delavayi complex.

Since the late Miocene, a gradual reduction in trichome base density has occurred in this complex. This trend is the opposite of that of precipitation, indicating that increased trichome density is not an adaptation to dry environments.

The stomatal density (SD) of the Q. delavayi complex was the highest during the late Miocene, declined in the late Pliocene, and then increased during the present epoch. These values show an inverse relationship with atmospheric CO2 concentrations, suggesting that the SD of the Q. delavayi complex may be a useful proxy for reconstruction of paleo-CO2 concentrations.

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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