Fig 1.
Compressions of vegetative axes of Minostrobus chaohuensis.
(A) The widest stem. Rectangle indicating portion enlarged in Fig. 1E. PKUB12138. Scale bar = 10 mm. (B) Stem with the lower left part without epidermis, showing leaf cushions. Arrow indicating portion enlarged in Fig. 1K. PKUB12145. Scale bar = 10 mm. (C) Stem dichotomizing two times. PKUB12101. Scale bar = 10 mm. (D) Vegetative axis with leaf cushions arranged in helix. Arrow indicating portion enlarged in Fig. 1L. PKUB12137. Scale bar = 10 mm. (E) Enlargement of Fig. 1A (rectangle), showing parastichies of leaf cushions. PKUB12138. Scale bar = 5 mm. (F) Vegetative axis with leaf cushions arranged in helix. Rectangle indicating portion enlarged in Fig. 1I. PKUB12135. Scale bar = 5 mm. (G) Vegetative axis with long fusiform leaf cushions, showing leaf scars, ligule pits (Lp) and vascular scars (Vs). PKUB12171. Scale bar = 5 mm. (H) Vegetative axis showing interareas with vertical linear ornamentations among leaf cushions. PKUB12163. Scale bar = 2 mm. (I) Enlargement of Fig. 1F (rectangle), showing long fusiform leaf cushion and ornamentations on the interareas. PKUB12135. Scale bar = 1 mm. (J) Vegetative axis with leaf cushions, showing the oblanceolate leaf scars. PKUB12148. Scale bar = 2 mm. (K) Enlargement of Fig. 1B (arrow), showing leaf scar, ligule pit (Lp) and vascular scar (Vs). PKUB12145. Scale bar = 1 mm. (L) Enlargement of Fig. 1D (arrow), showing leaf scar and ligule pit (Lp). PKUB12137. Scale bar = 1 mm.
Fig 2.
Diagram of the leaf cushion of Minostrobus chaohuensis.
Oblanceolate leaf scar, ligule pit (Lp) and vascular scar (Vs). Scale bar = 1 mm.
Fig 3.
Compressions of leafy axes and leaves (A-D, G, H), limonite permineralized strobili (E, F, I-K) of Minostrobus chaohuensis.
(A) Dichotomous vegetative axes with persistent leaves. Rectangle indicating portion enlarged in Fig. 3H. PKUB12124. Scale bar = 10 mm. (B) Distal part of vegetative axis with persistent leaves. Rectangle indicating portion enlarged in Fig. 3C. PKUB12139. Scale bar = 10 mm. (C) Enlargement of Fig. 3B (rectangle), showing the lanceolate leaf in face view. PKUB12139. Scale bar = 2 mm. (D) Lanceolate vegetative leaf in face view. PKUB12159. Scale bar = 2 mm. (E) Limonite permineralized megasporangiate strobilus. Rectangle indicating portion enlarged in Fig. 3J. PKUB12188. Scale bar = 5 mm. (F) Limonite permineralized microsporangiate strobilus. Arrow indicating portion enlarged in Fig. 3I. Rectangle indicating portion enlarged in Fig. 3K. PKUB12189. Scale bar = 10 mm. (G) Detached vegetative leaves in the matrix. PKUB12160. Scale bar = 2 mm. (H) Enlargement of Fig. 3A (rectangle), showing vegetative leaves in lateral view and rhombus leaf bases. PKUB12124. Scale bar = 5 mm. (I) Enlargement of Fig. 3F (arrow), showing laminae of microsporophyll. PKUB12189. Scale bar = 2 mm. (J) Enlargement of Fig. 3E (rectangle). Arrow indicating megaspores. PKUB12188. Scale bar = 2 mm. (K) Enlargement of Fig. 3F (rectangle), showing strobilar axis and microsporangia on the adaxial surface of sporophyll pedicel. PKUB12189. Scale bar = 2 mm.
Fig 4.
Sections of the permineralized microsporangiate strobilus of Minostrobus chaohuensis in Fig. 3F, under LM.
(A) Longitudinal section of strobilus, showing sporophylls and sporangia. Arrow indicating portion enlarged in Fig. 4B. PKUB12189-3-4. Scale bar = 2 mm. (B) Enlargement of Fig. 4A (arrow), showing microsporangium with numerous microspores and alations (Al) of sporophyll. PKUB12189-3-4. Scale bar = 0.5 mm. (C) Radial section of strobilus, showing strobilar axis, sporophylls and microsporangia. Arrows indicating portions enlarged in Fig. 4D and Fig. 4J. PKUB12189-3-3. Scale bar = 2 mm. (D) Enlargement of Fig. 4C (upper arrow), showing sporangium containing microspores and subarchesporial pad. Rectangle indicating portion enlarged in Fig. 4I. PKUB12189-3-3. Scale bar = 0.2 mm. (E) Transverse section of strobilus, showing strobilar axis and microsporangia. Arrow indicating portion enlarged in Fig. 4F. PKUB12189-2-3. Scale bar = 1 mm. (F) Enlargement of Fig. 4E (arrow), showing exarch primary xylem of strobilar axis. PKUB12189-2-3. Scale bar = 0.1 mm. (G) Transverse section of strobilus. Arrows indicating transverse view of sporophylls. PKUB12189-1-4. Scale bar = 1 mm. (H) Transverse section of uniseriate sporangial wall, showing columnar cells and microspores in the sporangium. Rectangle indicating portion enlarged in Fig. 4K. PKUB12189-2-5. Scale bar = 0.1 mm. (I) Enlargement of Fig. 4D (rectangle), showing subarchesporial pad and microspores in sporangium. PKUB12189-3-3. Scale bar = 50 μm. (J) Enlargement of Fig. 4C (lower arrow), showing xylem strand of strobilar axis and metaxylem tracheids with scalariform thickenings. PKUB12189-3-3. Scale bar = 0.1 mm. (K) Enlargement of Fig. 4H (rectangle), showing microspore tetrads and the inner body. PKUB12189-2-5. Scale bar = 50 μm.
Fig 5.
Line drawing of Fig. 4C.
Radial section of microsporangiate strobilus of Minostrobus chaohuensis. Scale bar = 1 mm.
Fig 6.
SEM observations of microspores of Minostrobus chaohuensis.
(A) Tetrads of microspores. Arrow indicating portion enlarged in Fig. 6B. Scale bar = 50 μm. (B) Enlargement of Fig. 6A (arrow), showing a tetrad with four visible microspores. Scale bar = 10 μm. (C) A tetrad with one of the microspores broken in the distal face. Scale bar = 10 μm. (D) A microspore showing the trilete and cingulum. Scale bar = 10 μm. (E) A microspore showing the inner and outer exospores. Scale bar = 5 μm. (F) Foveolate outer exospore of the microspore. Scale bar = 5 μm.
Table 1.
Comparisons of main characters of Minostrobus chaohuensis (vegetative axis and microsporangiate strobilus) described by Wang et al. [8] and this study.