2 Description of the Specimens. 1 Materials and Methods. ZHOU Yi-Long 1, LIU Xian-Wei 2, WANG Shi-Jun 1*, CHEN Gui-Ren 3, TIAN Bao-Lin 3

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1 Acta Botanica Sinica 2004, 46 (11): On the Anatomical Structures of the Lepidodendralean Stem Lepidodendron tripunctatum from Coal Balls of Taiyuan Formation in Shandong Province, North China ZHOU Yi-Long 1, LIU Xian-Wei 2, WANG Shi-Jun 1*, CHEN Gui-Ren 3, TIAN Bao-Lin 3 (1. Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing , China; 2. North China Institute of Science and Technology, Beijing , China; 3. China University of Mining and Technology, Beijing , China) Abstract: An anatomically preserved lepidodendralean stem is described from coal balls of the early Early Permian or late Late Carboniferous Taiyuan Formation in Tao-Zao and Yanzhou coal fields from southern Shandong, North China. The stem bears leaf cushions previously assigned into Lepidodendron tachingshanense Lee, but is renamed as Lepidodendron tripunctatum Stock. et Math. based on the morphology of the leaf cushion in this study. Comparison and relationship between L. tripunctatum and other anatomically preserved lepidodendralean stems from the middle Late Carboniferous Euramerican and the late Late Carboniferous or early Early Permian Cathaysian floras is made and discussed. Key words: Cathaysian Flora; Taiyuan Formation; coal ball; lepidodendralean stem; Lepidodendron tripunctatum ; anatomy The coal balls in Coal Seam No. 16 of the early Early Permian or late Late Carboniferous Taiyuan Formation in Tao-Zao and Yanzhou coal-fields, southern Shandong Province, yield abundant anatomically preserved lepidodendralean plants. Among them one kind of leaf Lepidophylloides hippocrepicus Wang, Tian et Chen and two kinds of stem Lepidodendron pulchrum Zhang and Diaphorodendron rhombicum Wang, have been reported recently (Wang et al., 2002; Chen et al., 2003; Wang, 2004). The third kind of lepidodendralean stem is reported in this paper. It is studied in detail both on its morphology and anatomy and is assigned into L. tripunctatum based on the morphological features of the leaf cushion. The comparison between it and other known anatomically preserved lepidodendralean stems from the Euramerican and Cathaysian floras is made. 1 Materials and Methods The material in this investigation includes two specimens of the lepidodendralean stem. One of them was collected from Beisu Coal Mine of Yanzhou Coal-field and is numbered as YB-24. It is flattened with a long axis of 11 cm and a short axis of 4 cm. The other one was collected from Shanjialin Coal Mine of Tao-Zao Coal-field and is numbered as SS-26. It is also flattened and incompletely preserved. Its long axis probably can reach up to 9 cm and its short axis is 3.5 cm. In both specimens the outer cortex, periderm and leaf cushions are well preserved, but the stele is only preserved in YB-24, not in SS-26. No secondary xylem is developed in both specimens. In order to obtain the detailed morphological features of the leaf cushion, we knocked the coal ball containing the specimen SS-26 and the surface of the leaf cushion was exposed out. The peeling method is employed in this investigation (Phillips et al., 1976; Galtier and Phillips, 1999). The geological background of the coal ball localities was introduced in detail by Guo et al. (1990). 2 Description of the Specimens Lepidodendron Sternburg sensu DiMichele, 1983 L. tripunctatum Stock. et Math., 1939 (Figs.1-19) 1995 Lepidodendron tachingshanense Lee: Tian and Wang, Pl. 58, Figs.3, 4 Diagnosis emended Leaf cushion vertically elongated rhomboid with its top and basic angle more or less obliquely truncate. Leaf scar large and asymmetrically rhomboid in shape with its upper sides slightly longer than the lower ones and located at the middle and upper part of the leaf cushion. Parichnos scars and vascular scar small and circular. The most high-rising part of the leaf cushion just below the leaf scar and the upper part of the leaf cushion Received 16 Mar Accepted 20 Aug Supported by the Knowledge Innovation Program of The Chinese Academy of Sciences (KSCX2-SW-108), the National Natural Science Foundation of China ( ) and the Project of F orward Research Field from the Institute of Botany, The Chinese Academy of Sciences. * Author for correspondence. <wangsj@ibcas.ac.cn>.

2 (containing the leaf scar) inclined upward. Transverse plicate weakly developed or absent. Stem siphonostelic with mixed pith. Outer margin of the metaxylem smooth. Inner and middle cortex unknown. Outer cortex 9-10 mm wide and consisting of alternatively arranged radial thick-walled cell bands and thin-walled cell areas. In tangential section the outer cortex vertically anastomosing and in the center of each thin-walled cell area being a vertically elliptical leaf trace. The vascular bundle of the leaf trace consisting of an upper horizontally elongated xylem strand, a lower crescent-shaped sclerenchyma strand and a middle thin-walled cell area probably of phloem. Vascular bundle sheath consisting of small and nearly isodiametric parenchyma cells. A mass of larger and loosely arranged parenchyma cells enclosing the upper side of the leaf trace. Periderm consisting of phellem and phelloderm. Phelloderm wider than phellem and consisting of alternatively arranged tangential thicker-walled cell bands and thinner-walled cell bands. Phellem uniform and consisting of vertically elongated thickwalled cells. Leaf trace and parichnos strand extending at a horizontal course in the leaf cushion. Ligule large and stiff with a height and a largest radial diameter of more than 1 mm and a largest tangential diameter of µm. The aperture of ligule pit very close to the top angle of the leaf scar. 2.1 Stele Specimen YB-24 is siphonostelic and the stele is flattened with a long axis of 2.2 cm and a short axis of 1.1 cm (Fig.14). The primary xylem is exarch with a smooth outer margin or, in another word, the protoxylic poles are indistinct. The diameter of the metaxylic tracheids increases inward. The tracheids at the outer part are arranged contiguously, while in the center of the stele the tracheids are arranged loosely and mixed with small and thin-walled parenchyma cells (Fig.15), thus the stem possesses a mixed pith. There are scalariform thickenings with Williamson s striations on the metaxylic tracheid wall (Fig.10). The stele of specimen SS-26 is not preserved. 2.2 Cortex No inner and middle cortex have been observed in both specimens probably because of their poor preservation. Outer cortex is 7-10 mm wide in SS-26 and about 9 mm in YB-24. It consists of alternatively arranged radial thickwalled cell bands and cavities which represent the disappeared thin-walled cell areas (Figs.1-3). In SS-26, remnant of parenchyma tissue sometimes can be seen in the cavities. In tangential section through the outer cortex, the thickwalled cell bands are vertically anastomosing (Fig.11). In transverse section, the thick-walled cells are nearly isodiametric and triangular, square or polygonal in shape with their diameter increasing inward, from µm to µm or more in SS-26 and from µm to µm or more in YB-24. In longitudinal section, the thickwalled cells are vertically elongated with their length decreasing inward, from more than 100 µm long at the outermost part to only 10 µm at the innermost part. Parenchyma cells are nearly isodiametric in cross and longitudinal sections. Within some radial thick-walled cell bands there is a dark brown colored radial cell band consisting of smaller and thicker walled cells than the surrounding ones in YB- 24. In tangential section through the outer cortex, there is a leaf trace in each of cavity (Fig.11). The leaf trace is vertically elliptical in shape and consists of an upper horizontally elongated xylem strand, a middle horizontally elongated area consisting of thin-walled cells that probably is phloem and a lower crescent-shaped sclerenchyma strand with its concave side upward. Vascular bundle sheath consists of small and nearly isodiametric parenchyma cells. There is a mass of loosely arranged and large-sized parenchyma cells that enclose the upper side of the leaf trace (Fig.13). In radial section, leaf trace diverges at a very low angle from the outer surface of the primary xylem of the stem and is accompanied by some flattened sclerotic cells at its adaxial side. When, however, the leaf trace enters the outer cortex the sclerotic cells disappear. The leaf trace extends at a nearly horizontal course in the outer cortex and periderm till it enters the leaf cushion. 2.3 Periderm Periderm consists of two distinct parts: phellem and phelloderm. Phelloderm is mm wide in YB-24 and mm in SS-26. Phellem is weakly developed in YB-24 with the largest width of 0.5 mm. In SS-26 phellem is mm wide. Phelloderm consists of alternatively arranged tangential thicker-walled cell bands and thinner-walled cell bands and the latter are usually damaged into cracks (Fig. 16). Cells of phelloderm are nearly isodiametric or slightly radially elongated in cross section. In radial section they are vertically elongated with horizontal end wall (Fig.19). Phellem can be roughly divided into two zones: the inner one is in dark color due to the dark brown colored content in cells; the outer one, however, is in light color and cells are usually in poor preservation. In cross section cells of phellem are slightly smaller than those of phelloderm and are usually square in shape (Fig.16). In longitudinal section, cells of phellem are vertically elongated with tapered end wall (Fig.18). 2.4 Leaf cushion Morphology and size Figure 4 shows the surface

3 ZHOU Yi-Long et al.: On the Anatomical Structures of the Lepidodendralean Stem Lepidodendron tripunctatum from Coal Balls of Taiyuan Formation in Shandong Province, North China view of several leaf cushions of specimen SS-26. The leaf cushion is roughly rhomboid in shape with its height slightly larger than the width. Leaf scar is large and asymmetrically rhomboid in shape with its basic and lateral angles about 90 and its upper sides slightly longer than the lower ones. The most high-rising part of the leaf cushion is just below the leaf scar so that the surface of the leaf scar is inclined upward. There is a vertically elongated shallow depression in the middle part of the leaf scar (Fig.4). In the tangential section through the leaf cushion, the top and Figs.1-9. Lepidodendron tripunctatum Transverse section of the stem, showing leaf cushion (LC), periderm (Pd), outer cortex (OC) and stele (arrow). 4. Surface view of the leaf cushions, showing the shallow vertically elongated depression in the middle part of the leaf scar (arrow) Tangential section of the stem through leaf cushions, showing the form and arrangement of leaf cushions. Note that at the left lower part of Fig.6 only the lower part of the leaf cushions can be seen, which means that the lower part is higher-rising than the upper part of the leaf cushion. 8. Higher magnification of the vascular bundle (VB) in Fig.12, showing broad V-shaped xylem strand. 9. Higher magnification of a part in Fig.17, showing ligule (LG).

4 basic angles of the leaf cushion of both specimens are obliquely truncate which makes the leaf cushion into an unequal-laterally pentagonal or hexagonal outline (Figs.5-7). The leaf cushion is 8-9 mm high and 6-7 mm wide in SS-26 and a little smaller in YB-24, 6 mm high and 4-5 mm wide. They are contiguously and spirally arranged. In radial section through the middle part of the leaf cushion of SS-26, the maximum thickness, 3.5 mm, of the leaf cushion is just below the leaf scar and the thickness gradually decreases upward. Thus the leaf scar is inclined upward (Fig.17), which is consistent with the morphological feature (Fig.4). When making a series of tangential sections inward through the leaf cushion we shall firstly cut the lower part of the leaf cushion (Fig.6), which indicates that the lower part of the leaf cushion of the present specimens is most high-rising Anatomy Several layers of cells beneath the epidermis are usually with secretory contents and in poor preservation. Inside these cells are nearly isodiametric parenchyma cells without content. The leaf trace enters the middle part of the leaf cushion and extends outward at a nearly horizontal course. Parichnos strand is just below the leaf trace and in a V-shape with its concave side upward when it enters the leaf cushion. There is a small mass of thick-walled cells with very small diameter at the lower part of the leaf cushion (Fig.12). When the leaf trace and parichnos strand reach the base of the ligule pit, the parichnos strand is divided into two and the mass of small thick-walled cells is located between the two branches of the parichnos strand. Leaf trace is semicircular or nearly heart-shaped and consists of the lower arc-shaped or wide V-shaped sclerenchyma strand and the upper V-shaped xylem strand (Figs.8,12). Vascular bundle sheath is composed of 1-2 layers of small and usually poor preserved cells. Cells between the leaf trace and ligule pit are mostly radially elongated and rectangular in shape among which those close to the leaf trace with spiral thickenings are probably transfusion cells. Ligule pit is located at the outer part of the leaf cushion and is very close to the surface of the leaf scar (Figs.9,17). Ligule nearly fills up the whole pit and the both are nearly in same shape. In radial section, height of the ligule decreases from the outer side to the inner side, so that the ligule is in a shape of a right triangle (Fig.9). In tangential section the ligule is vertically elongated (Fig.12) and similar to the shallow depression in the middle part of the leaf scar in shape (Fig.4). The largest height of the ligule is mm in SS-26 and mm in YB-24. The largest radial diameter of the ligule is nearly the same as the largest height in SS-26 and the largest tangential diameter is µm in SS-26 and µm in YB-24. Ligule consists of small and slightly vertically elongated cells with dark brown content, so that the ligule is dark brown colored as a whole. Ligule is located at the bottom of the ligule pit by a broad base. The aperture of the ligule pit is probably very close to the top angle of the leaf scar. 3 Comparison 3.1 Comparison with the Cathaysian lepidodendralean stems in impression-compression preservation There are several leaf cushions on the stem of SS-26 bearing the morphological features (Fig.4) which make it possible to compare them with the Cathaysian lepidodendralean stems in impression-compression preservation. They resemble those of Lepidodendron tripunctatum Stock. et Math. in possessing the asymmetrically rhomboid leaf scar with its upper sides slightly longer than the lower ones and its basic and lateral angles of about 90. Furthermore, in some specimens of L. tripunctatum (including the present specimens) there is a shallow vertically elongated depression in the middle part of the leaf scar (Fig.4; Gu et Zhi, 1974, Pl.9, Figs.7-10). L. tachingshanense Lee is comparable to the present specimens in possessing the unequal-laterally pentagonal or hexagonal leaf cushion and large and rhomboid leaf scar, which caused the stem to be assigned into the species by some of the authors of this paper (Tian and Wang, 1995). However, the rhomboid leaf scar of L. tachingshanense has an equal upper and lower sides, and its basic angle is obviously less than 90 and lateral angles are larger than 90. Besides, there is not a shallow vertically elongated depression in the middle part of the leaf scar in L. tachingshanense (Li, 1963, Pl. 16, Fig.5, Pl.18, Figs.1-4). Moreover, leaf cushions of some specimens of L. tripunctatum in impression-compression preservation are also more or less unequal-laterally pentagonal or hexagonal in form (Gu et Zhi, 1974, Pl.9, Figs.9, 10). Thus, we prefer to assign the present specimens into L. tripunctatum rather than L. tachingshanense. 3.2 Comparison with the other anatomically preserved lepidodendralean stems T he a natomica lly pr ese rve d E ur ame ric an lepidodendralean stems with vertically elongated leaf cushion are assigned into five genera, including Lepidodendron Sternburg sensu DiMichele, Diaphorodendron (DiMichele) DiMichele et Bateman, Synchysidendron DiMichele et Bateman, Paralycopodites (Morey et Morey) DiMichele and Hizemodendron Bateman et DiMichele. Among these genera, Diaphorodendron and Synchysidendron are closely related to each other and belong to the same family

5 ZHOU Yi-Long et al.: On the Anatomical Structures of the Lepidodendralean Stem Lepidodendron tripunctatum from Coal Balls of Taiyuan Formation in Shandong Province, North China Figs Lepidodendron tripunctatum. 10. Scalariform thickenings with Williamson s striations (arrow) on the metaxylic tracheid wall. 11. Tangential section through the outer cortex, showing vertically anastomosing thick-walled cell bands. In each cavity there is a leaf trace (arrows). 12. Tangential section through a leaf cushion showing ligule (LG), vascular bundle (VB), parichnos strand (Par) and a mass of small thick-walled cells (arrow). 13. Higher magnification of a leaf trace in Fig.11, showing xylem strand (XS), V-shaped sclerenchyma strand (SS) and probable phloem between them. The lower arrow indicates the vascular bundle sheath consisting of small and nearly isodiametric parenchyma cells and the upper one indicates a mass of loosely arranged large-sized parenchyma cells that enclose the upper side of the leaf trace. 14. Stele consisting of the outer contiguously arranged tracheids (X1) and the central mixed pith (P). 15. High magnification of the mixed pith in Fig.14, showing large and elongated tracheids and small and poorly preserved parenchyma cells. 16. Periderm showing phellem (Pm) and phelloderm (Pr). 17. Radial section through the middle part of a leaf cushion showing high-rising lower part (large arrow) and tapered upper part (small arrow). 18. Radial section through the phellem. 19. Radial section through the phelloderm. Coal balls: YB-24 (Figs.1,5,8,10-15); SS-26 (Figs.2-4,6,7,9,16-19). Scales: 1 cm (Fig.2); 5 mm (Figs.4,7); 4 mm (Fig.14); 3 mm (Fig.11); 2 mm (Fig.13); 1 mm (Figs.1, 3, 5, 6, 17); 500 µm (Figs.9, 12, 16); 200 µm (Figs.8, 15, 18, 19); 20 µm (Fig.10).

6 Diaphorodendraceae (DiMichele and Bateman, 1992). Both of them possess the distinct bi-zoned periderm consisting of phellem and phelloderm. Phelloderm consists of alternatively arranged tangential thicker-walled cell bands and thinner-walled cell bands and the latter tends to be cracks or holes when the specimens are in poor preservation (DiMichele and Bateman, 1992). However the periderm of the other three genera consists of uniform thick-walled cells or, in other words, does not differentiated into phellem and phelloderm (DiMichele, 1980; 1983; Bateman and DiMichele, 1991). The periderm of the present specimens is comparable to that of Diaphorodendron and Synchysidendron in being distinctly bi-zoned or differentiated into phellem and phelloderm. In Diaphorodendron its outer cortex consists of alternatively arranged radial thick-walled cell bands and thin-walled cell areas which, however, is weakly developed in Synchysidendron. In other three genera, i.e. Lepidodendron, Paralycopodites and Hizemodendron, the outer cortex consists of uniform thick-walled cells. Thus the present specimens are consistent with Diaphorodendron in the histology of outer cortex. The type of stele is also one of the important diagnosis in distinguishing lepidodendralean stems. For example, only the stem of Diaphorodendron possesses a protostele or a siphonostele with the mixed pith. While the stems of the other four genera, i.e. Synchysidendron, Lepidodendron, Paralycopodites and Hizemodendron, typically possess the siphonostele with parenchymatous pith. The present specimens possess a stele with mixed pith, which is close to Diaphorodendron. Thus, from the states as above, the present specimens are comparable to Diaphorodendron in the histology of periderm and outer cortex and in the type of stele. There are four species in Diaphorodendron at present. Three of them, D. scleroticum, D. vasculare and D. phillipsii were distributed in the Euramerican Flora and only one species, D. rhombicum, was distributed in the Cathaysian Flora. D. rhombicum is quite different from the Euramerican species of Diaphorodendron in the morphology and anatomy of leaf cushions. The leaf cushion of D. rhombicum is in the form of diamond with nearly equal height and width. The aperture of the ligule pit is very close to the top angle of the leaf scar. Ligule is large and stiff with a length of more than 1 mm and a diameter of nearly 1 mm (Wang, 2004). The leaf cushion of the Euramerican species is fusiform with a large ratio of height:width, from 2:1 to 4:1. The aperture of the ligule pit is a little away from the top angle of the leaf scar. Ligule is small and delicate with its length of no more than µm and width of µm (DiMichele, 1979; 1981; DiMichele and Bateman, 1992). Obviously the present specimens are very close to D. rhombicum in possessing the leaf cushion with small ratio of height:width, large and stiff ligule and the aperture of the ligule pit very close to the top angle of the leaf scar. The only difference between D. rhombicum and the present specimens is in the shape of the leaf scar: horizontally elongated in D. rhombicum and rhomboid in the present specimens. The Euramerican species of Diaphorodendron, however, are quite different from the present specimens in the form of the leaf cushion, the size of ligule and the place of the aperture of the ligule pit as well as the shape of the leaf scar. Probably there is a close relation between the present specimens and D. rhombicum. 4 Discussion L. tripunctatum was erected by Stockman and Mathieu (1939) based on the impression-compression preservative specimens from Hebei Province. Its geological age was from Westphalian of the Late Carboniferous to the Early Permian. However, the reported specimens of the species up to date are all of impression-compression preservation. Thus our investigation in this paper is the first report on the anatomical features of L. tripunctatum. In some impression-compression preservative specimens of L. tripunctatum there is a shallow vertically elongated depression in the middle part of the leaf scar, however, no other researchers have given the explanation to it and we do not know how it has been formed. Now we can try to give the explanation to this. In Figs.9 and 17 of this paper we can see that the ligule pit is very close to the surface of the leaf scar, which make the ligule pit easy to collapse and form a shallow vertically elongated depression with the same form as the ligule pit or ligule (Fig.12). However, in other lepidodendralean stems such as D. rhombicum (Wang, 2004), L. pulchrum (Chen et al., 2003) and L. lepidophloides (Wang et al., 2002), between ligule pit and the surface of leaf scar there is thick tissue which makes ligule pit uneasy to collapse, thus no vertically elongated depression was formed in the middle part of the leaf scar of these stems in impression-compression preservation (Zhao et al., 1980; Zhang, 1987). U p to no w, four a na to mi c ally p r eser ve d lepidodendralean stems have been reported from Taiyuan Formation of North China and they are all distributed in Tao-Zao and Yanzhou coal-fields, soutern Shandong Province. They are L. pulchrum (Chen et al., 2003), L. posthumii (Tian and Wang, 1995), D. rhombicum (Wang,

7 ZHOU Yi-Long et al.: On the Anatomical Structures of the Lepidodendralean Stem Lepidodendron tripunctatum from Coal Balls of Taiyuan Formation in Shandong Province, North China 2004) and L. tripunctatum (in this paper). L. posthumii was published only by illustration (Tian and Wang, 1995, Pl.58, Figs.1, 2) without any description and comparison. The stem resembles the present specimens in the histology of periderm and outer cortex and the type of stele and only differs in possessing the leaf cushion with a larger ratio of height to width, about 2:1. L. posthumii is very close to Diaphorodendron but differs in the shape of the leaf scar. It is usually smaller and transversely elongated and located at the upper part of the leaf cushion in Diaphorodendron but is larger and slightly vertically elongated rhomboid and located at the middle part of the leaf cushion in L. posthumii. It is worthy to notice that L. pulchrum, L. posthumii, D. rhombicum and L. tripunctatum, although they possess different forms of the leaf cushion, are consistent with each other in many anatomical features such as the histology of the periderm and outer cortex and the type of stele. This means that there may be a close relation between these stems. There also is a close relationship between them and the Euramerican species of Diaphorodendron, which is not clear at present and need to be further studied in the future. References: Bateman R M, DiMichele W A Hizemodendron, gen. nov., a pseudoherbaceous segregate of Lepidodendron (Pennsylvanian): phylogenetic context for evolutionary changes in lycopsid growth architecture. System Bot, 16: Chen G-R, Wang S-J, Tian B-L Anatomical structures of Lepidodendron pulchrum Zhang in coal balls from the Taiyuan Formation (lower Lower Permian) in Shandong Province, North China. Acta Bot Sin, 45: DiMichele W A Arborescent lycopods of Pennsylvanian age coals: Lepidodendron dicentricum C. Felix. Palaeontographica B, 171: DiMichele W A Paralycopodites Morey and Morey, from the Carboniferous of Euramerica a reassessment of the generic affinities and evolution of Lepidodendron brevifolium Williamson. Am J Bot, 67: DiMichele W A Arborescent lycopods of Pennsylvanian age coals: Lepidodendron, with a description of a new species. Palaeontographica B, 175: DiMichele W A Lepidodendron hickii and generic delimitation in Carboniferous lepidodendrid lycopods. System Bot, 8: DiMichele W A, Bateman R M Diaphorodendraceae, fam. nov. (Lycopsida: Carboniferous): systematics and evolutionary relationships of Diaphorodendron and Synchysidendron, gen. nov. Am J Bot, 79: Galtier J, Phillips T L The acetate peel technique. Fossil Plants and Spores: modern Techniques. Bath: The Geological Society of London Gu et Zhi (Institute of Nanjing Geology and Paleontology, Institute of Botany of the Chinese Academy of Sciences) Fossil Plants of China. I. Paleozoic Plants of China. Beijing: Science Press (in Chinese) Guo Y-T, Chen G-R, Wang S-J Research on the coal balls from Taiyuan Formation, Late Carboniferous in Southern Shandong. Exploration Geosci, 3: Phillips T L, Avin M J, Berggren D Fossil Peat from the Illinois Basin: a Guide to the Study of Coal Balls of Pennsylvanian Age. Education Ser. ò, ó. Urbana: State Geological Surveys, Tian B L, Wang S J Paleozoic coal ball floras in China. Li X X. Fossil Floras of China Through the Geological Ages. Guanzhou: Guangdong Science and Technology Press Wang S-J, Tian B-L, Chen G-R Anatomical structures of leaf cushion of Lepidodendron lepidophloides Yao. Acta Bot Sin, 44: Wang S-J Diaphorodendron rhombicum sp. nov., a new anatomically preserved lepidodendralean stem from the Taiyuan Formation in southern Shandong Province, North China. Acta Bot Sin, 46: Zhang H Paleobotany. Institute of Geology and Exploration, CCMRI, Ministry of Coal Industry and Provincial Coal Exploration Corporation of Shanxi. Sedimentary Environment of the Coal-bearing Strata in Pinglu-Shuoxian Mining Area, China. Xi an: Shaanxi People s Education Publishing House (in Chinese with English abstract) Zhao X-H, Mo Z-G, Zhang S-Z, Yao Z-Q Late Permian flora from western Guizhou and eastern Yunnan. Nanjing Institute of Geology and Palaeontology, The Chinese Academy of Sciences. Stratigraphy and Palaeontology of the Upper Permian Coal Measures of West Guizhou and East Yunnan. Beijing: Science Press (in Chinese) (Managing editor: HAN Ya-Qin)