The coast redwoods (Sequoia, Taxodiaceae) from the Eocene of Heilongjiang and the Miocene of Yunnan, China

Foliated shoots of Sequoia are reported from the Eocene of Yilan, Heilongjiang Province, NE China and from the Miocene of Lühe, Yunnan Province, South China. The leaves from both Yilan and Lühe are linear in shape, coriaceous in texture and the leaf base is decurrent and attached obliquely to the axis of shoots. The walls of the epidermal cells are straight, and the long axis of stomata is mostly parallel to mid-vein in our specimens. It suggests that the new specimens are assignable to Sequoia rather than to the similar genera Metasequoia, Taxodium and Glyptostrobus. The leaves from Yilan tend to be straight, but they are bent outwards in specimens from Lühe, very similar to those of Sequoia sempervirens. The leaves from Lühe are amphistomatic, while those from Yilan are hypostomatic. The stomata of the leaves from Lühe possess guard cells with polar lamellae, a feature missing in the leaves from Yilan. The gross morphology of foliated shoots, female cones, and the epidermal features from Lühe agree with those of S. sempervirens, so the specimens from Lühe are assigned to S. cf. sempervirens. The foliated shoots and epidermises of the specimens in Yilan are fit within the diagnosis of Sequoia chinensis, and therefore, the specimens are assigned to this species. The presence of Sequoia during the Eocene in Yilan and Miocene in Lühe is proven by the cuticle, which resolves some problems of identification.