Pinus Pollen Cones from the Middle Eocene Princeton Chert (Allenby Formation) of British Columbia, Canada
Pinus Pollen Cones from the Middle Eocene Princeton Chert (Allenby Formation) of British Columbia, Canada
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DOI：
10.1086/297232
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发表时间：
1995-01
影响因子：
2.3
通讯作者：
C. J. Phipps;J. Osborn;R. Stockey
中科院分区：
文献类型：
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作者：
C. J. Phipps;J. Osborn;R. Stockey
加拿大不列颠哥伦比亚省中始新世普林斯顿硅质岩中描述了解剖保存下来的花粉球果。球果为椭圆形，长2.8至6.9毫米，直径1.6至3.5毫米，常有鳞片覆盖。锥体轴含有纵向的皮质树脂管和14-18个维管束。小孢子叶螺旋排列，每个具两个背面的花粉囊，其中许多含有花粉粒。颗粒为双硫酸盐和单硫酸盐，长50-70μm，宽27-43μm。近端，体部皱纹，有覆盖状蜂窝状的基础结构。SACCI具有明显的内网，外部纹饰呈鳞片状。球果大小、球果解剖和花粉形态的变化表明，有几个发育阶段被保存下来。硅质岩中存在大量的球果，特别是那些代表短暂的个体发生阶段的球果，以及球果的保存性质，支持快速埋藏和保存的沉积解释。这些因素还表明，产生花粉锥的植物在靠近湖泊环境的地方占据了边缘位置。四种松树，以木质树枝、矮枝、树叶和卵形球果为基础，目前在普林斯顿冰川中已知。这些花粉球果与樟子松叶片和华山松卵形球果的联合表明了这些物种之间可能的分类亲缘关系。普林斯顿硅质岩标本是被描述的最古老的松属花粉球果，也是第一个被描述化石花粉超微结构的属。
Anatomically preserved pollen cones are described from the Middle Eocene Princeton chert of British Columbia, Canada. Cones are ellipsoidal; range from 2.8 to 6.9 mm in length, 1.6 to 3.5 mm in diameter; and are often subtended by scale leaves. Cone axes contain longitudinally oriented, cortical resin canals and 14-18 vascular bundles. Microsporophylls are helically arranged, each bearing two abaxial pollen sacs, many containing pollen grains. Grains are bisaccate and monosulcate, ranging from 50 to 70 μm in length and 27 to 43 μm in width. Proximally, the corpus is rugulate with a tectate-alveolate infrastructure. Sacci have a well-defined endoreticulum and an external ornamentation that is psilate to scabrate. Variations in cone size, cone anatomy, and pollen morphology indicate that several developmental stages are preserved. The large number of cones present in the chert, especially those representing short-lived ontogenetic stages, and the preservational quality of the cones support depositional interpretations for a rapid burial and preservation. These factors also indicate that the pollen cone-producing plants occupied a marginal position in proximity to the lacustrine environment. Four species of Pinus, based on woody twigs, dwarf shoots, leaves, and ovulate cones, are presently known from the Princeton chert. The association of these pollen cones with Pinus similkameenensis leaves and Pinus arnoldii ovulate cones indicates possible taxonomic affinities among these species. The Princeton chert specimens are the oldest Pinus pollen cones to be described and are the first in the genus for which fossil pollen ultrastructure has been described.