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A New Species of Ginkgo with Male cones and pollen Grains in situ from the Middle Jurassic of Eastern Xinjiang,China

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Acta Geologica Sinica(English Edition) 2017年第1期91卷 9-21页

作者： WANG Zixi SUN Fankai JIN Peihong CHEN Yingquan CHEN Jingwei DENG Peng YANG Guolin SUN Bainian School of Earth Sciences & Key Laboratory of Mineral Resources in Western China (Gansu Province) Lanzhou University Key Laboratory of Petroleum Resources Gansu ProvinceChinese Academy of Sciences

Well-preserved Ginkgo pollen organs are analyzed from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, and are described as a new species, Ginkgo hamiensis Z.X. Wang et B.N. Sun sp. nov. The immature male cones are cylindrical and catkin-like, with two longitudinal stripes on the stalk. The pollen sacs are shaped like a long oval with two pollen sacs fused together for each microsporophyll, and the microsporophyll tip is a triangular cystidium. The pollen grains are oblong or fusiform and monocolpate; both ends are blunt or sharp. By comparison with previously reported fossil records of Ginkgo plants, we determined that the current fossils are different from all other reported species; thus, the present fossil is referred to as a new species of Ginkgo. The reproductive organs of the Ginkgo fossils described herein can provide valuable information for the study of Ginkgo plants. Further, there are two probable evolutionary trends in the Ginkgo pollen cones. One trend is that the number of pollen sacs changed from three or four during the Jurassic and Cretaceous to two at the present day; the other is that the number of pollen sacs has remained two from the Middle Jurassic to the present day. In addition, the pollen cones described herein are similar to the pollen cones of the extant Ginkgo, which strongly indicates that the morphology of Ginkgo plants may have remained highly conserved over millions of years.

关键词： Ginkgo hamiensis pollen cones Middle Jurassic Xinjiang Uygur Autonomous Region Systematic evolution

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Wind pollination in Pinus roxburghii

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Progress in Natural Science:Materials International 2007年第1期17卷 32-38页

作者： Vinod Prasad KHANDURI Chandra Mohan SHARMA Department of Forestry Mizoram University Aizawl(Mizoram)India Department of Forestry HNB Garhwal University Srinagar Garhwal-246 174(Uttaranchal)India

Stigmatic pollen load and pollen concentration in the air were studied in the natural population of Pinus roxburghii at Ashtavakra (900 m asl), in the Pauri forest division of Garhwal Himalaya, India. The results reflect diurnal pollen occurrence in P. roxburghii , with the strong significant correlations between pollen concentrations in the air and wind speed, air temperature and relative air humidity. A significant correlation was also observed between microsporangium dehiscence and pollen occurrence in the air. The maximum concentration of pollen grains in the air and higher rates of pollen deposition onto the megasporophylls were between 12 pm and 16 pm of the day, which conforms the best time for pollination in a day in P. roxburghii. The receptivity of Ovulate strobili varied from 3 to 5 days, however, the bagged strobili remained receptive up to 6 days.

关键词： ovulate strobili pollen cones pollination receptivity wind speed P. roxburghii.

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