J Integr Plant Biol. ›› 1963, Vol. 11 ›› Issue (3): -.

• Research Articles •    

Cyathea ordosica C. N. Chu, A New Cyatheoid Fern from the Jurassic of Dongsheng, The Inner Mongolia Autonomous Region

Chu Chia-nan   

Abstract: The Dongsheng fossil Cyathea ordosica sp. nov., described here, is obtained from the Jurassic coal series in the district Dongsheng (=Tungsheng, 39˚53′N, 110˚ E). The Inner Mongolia Autonomous Region. From the same bed the following plants have been found, namely, Raphaelia diamensis Thomas, Cladophlebis whitbiensis Brongn., Taeniopteris vittata Brongn., Nilssonia sinensis Yabe et Oishi, Podocarpites mentoukauensis Stockmans et Mathieu and Pityophyllum sp. Besides, many other species have been observed at other spots of the same series, such as Annulariopsis simpsoni (Phillips) Harris, Clathropteris obovata Oishi, Coniopteris hymenophylloides Brongn., Czekanowskia rigida Heer, Phoenicopsis speciosa Heer, Elatocladus manchurica Yok. and Sagenopteris philIipsi (Brongn.) Presl. The geological age of the series is assigned to the Middle Jurassic by Prof. J. Hsü. The diagnosis of this new fossil plant is as follows: Frond tripinnate, large and elegent. Texture very thin. Pinna-raches marked with small pit-like scars representing the bristles, more than 100 in number per square centimeter. Venation free, catadromic branching. Penultimate pinnae broadly ovate, deltoidovate or auriculate, about 7 cm long and 5 cm broad. Ultimate pinnae subopposite or alternate, closely set, lanceolate or subfalcate, about 1.5–3.5 cm long and about 1 cm broad, obliquely upward; tip slightly obtuse (Pl. Ⅰ, figs. 6, 7), base sessile, cuneate, unequal. Pinnuleraches slender and thinner than the ultimate pinna-raches, alternate and catadromic branching, with longitudinal striations on their surface (Pl. Ⅱ, fig. 8). Pinnules alternate, touching each other, oblong, about 4 mm long and 1.5 mm broad, entire in the upper part, lobed in the lower part, with lobes arising at an acute angle (about 50˚–80˚). Midrib distinct in the basal part, frequently shifting to the lower side; veins alternate, arising at an acute angle (about 60˚), 2 to 3 in number on both sides of the midrib, slightly arching, simple or rarely forked, all reaching the tip of each lobe. Epidermal cells of lower surface of the pinnules polygonal in shape; those on the lateral veins rectangular, with their long axis parallel to the veins (Pl. Ⅱ, fig. 11). Sori 2–8, arranged in two tiers, dorsifixed on the lateral veins, circular, about 50 in number per square centimeter. Indusium wanting. Sporangia elliptic or turbinate in shape, crowded, about 13–17 or more in number in each sorus, 10 μ in diameter, short-stalked. Annulus oblique, distinct, composed of one row of thickened cells (Pl. Ⅰ, figs. 2-4). Raciborski (1894, p. 29, tag. Ⅸ, figs. 3-4) first described a fossil plant as Alsophila polonica from the Liassic in Poland. Later Hirmer (1927, p. 641) changed its generic name to Alsophilites. But Alsophilites polonica (Raciborski) Hirmer appears to be not a member of Cyatheaceae, as the features of pinnae and venation, the number and arrangement of sori and the number of sporangia of this species are not of Cyathean type. The present fossil represents,, therefore, not only the oldest known cyathean species in China, but also in the whole world.

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