An unexpected noncarpellate epigynous flower from the Jurassic of China Author Fu, Qiang 0000-0002-6948-3747 CAS Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China Author Diez, Jose Bienvenido 0000-0001-5739-7270 Departamento de Geociencias, Universidad de Vigo, Vigo, Spain Author Pole, Mike Queensland Herbarium, Brisbane Botanical Gardens Mt Coot-tha, Toowong, Australia Author Ávila, Manuel García Departamento de Geociencias, Universidad de Vigo, Vigo, Spain & Facultade de Bioloxía, Asociación Paleontolóxica Galega, Universidade de Vigo, Vigo, Spain Author Liu, Zhong-Jian State Forestry Administration Key Laboratory of Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China zjliu@fafu.edu.cn Author Chu, Hang Tianjin Center, China Geological Survey, Tianjin, China Author Hou, Yemao Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China Author Yin, Pengfei 0000-0002-4520-5347 Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China Author Zhang, Guo-Qiang State Forestry Administration Key Laboratory of Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China Author Du, Kaihe Jiangsu Key Laboratory for Supramolecular Medicinal Materials and Applications, College of Life Sciences, Nanjing Normal University, Nanjing, China Author Wang, Xin 0000-0002-4053-5515 CAS Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China xinwang@nigpas.ac.cn text eLife 2018 e 38827 2018-12-18 7 1 24 https://doi.org/10.7554/eLife.38827.001 journal article 10.7554/eLife.38827.001 f8d4b5a9-d707-4d89-a64f-008bf33d9a76 5885020 Nanjinganthus dendrostyla gen. et sp. nov. Specific diagnosis the same as the genus. Description The flowers are frequently concentrated and preserved in groups on certain bedding surfaces ( Figures 1a–g and 2a–b ), although many of them are preserved as isolated individuals on other slabs. Flower bud Aflower bud is preserved as a coalified compression, 6.4 mm long and 3 mm wide, with characteristic longitudinal ribs on the sepals and petals ( Figure 2g ). The sepals are estimated to be 1.3–2.2 mm long and approximately 1.8 mm wide ( Figure 2g ). The petals (including the eclipsed portion) are estimated to be approximately 3.7 mm long ( Figure 2g ). The receptacle/ovary is approximately 3 mm in diameter ( Figure 2g ). Mature flower The flowers are preserved in various states (including coalification), with cup-form receptacle, epigynous with an inferior ovary, 8.4–10.7 mm in length and 6.8–12.8 mm in diameter, actinomorphic in the bottom and top views ( Figures 1 a-g , 2a-f,h , 3a-b,d-f , 4a-b,d,g , 5e-i , 6a,f,j,l and 7a,e ). The pedicel is approximately 0.76 mm in diameter ( Figure 6a,b ). Basally fused bracts 0.7–3.7 mm long are observed at the bottom in a few flowers, and a stoma is seen on a bract ( Figures 4 g-h , 7e,h, and 8h ). The receptacle is cup-form, 3–4.8 mm in diameter and 2–4.5 mm high, surrounded by a 0.3 mm thick wall in the bottom and sides, and covered by an ovarian roof from the above ( Figures 2h–i , 4d , 5h , 6a–b and 7a,e–f,i ). Scales are attached on the sides of the receptacle/ovary ( Figures 3a–b , 4a,g–h , 5i and 7a,e,i ). The sepals are 1.7–3 mm long and 2.7–4.3 mm wide, with two lateral rib-free laminar areas and usually four longitudinal ribs in the center, and attached to the receptacle rim with their whole bases ( Figures 2 c-f , 3d-f , 4a,b,d-e , 5i,l , 6l , 7e,i , 9a ). The elongated epidermal cells are, 44–156 µm x 33–54 µm, with straight cell walls in the middle region, while isodiametric epidermal cells 16–71 µm x 10–54 µm are seen in the lateral laminar areas of the sepals ( Figures 8g , 9 h-k and 10d-f ). The petals are 3.1–6.6 mm long, 1.9–5.4 mm wide, compressed to only about 11 µm thick, with two lateral rib-free laminar areas, a cuneate base, and 5–6 longitudinal ribs in the center, located inside the sepals on the rim of the receptacle ( Figures 2c–f,h,j , 4a,b,d , 6a,f , 7a,e,i , 8a–f , 9a– g ). The ribs are approximately 0.12 mm wide, forking only basally, with elongated epidermal cells with straight cell walls, 32–144 µm x 17–30 µm on the abaxial and 19–72 µm x 13–29 µm on the adaxial ( Figures 8 a-f , 10a-b ). The lateral laminar areas are free of ribs, and each is approximately 1.2 mm wide, with isodiametric epidermal cells 23–64 µm x 18–37 µm ( Figures 8e , 9g ). Apossibly immature stoma is seen on one of the petals ( Figure 10c ). An unknown organ (staminode?) is seen once on the rim of the receptacle ( Figure 6a,m ). The ovarian roof is horizontal, with smooth integral outer and inner surfaces, 0.14–0.22 mm thick, with a style vertically located on its center ( Figures 4c , 5h , 6f and 7a–c,e–g ). The style is 0.3–0.8 mm in diameter, with lateral branches that make the width of the style 3–6 mm ( Figures 2h–i , 3a–b , 5i–j , 6a,c and 7a–d ). The basalmost pair of the lateral branches appear oppositely arranged along the style ( Figures 2h and 3b ) while the upper ones appear irregularly arranged ( Figures 2i , 6a and 7c–d ). There are longitudinal faint striations on the surface of the style ( Figures 3c and 5j ). There are 1.6–3.6 mm long and 1.7–2.2 mm wide round-triangular scales on the sides of the ovary ( Figures 2g , 3b , 4a,g–h and 5i ). Each ovary contains one to three seeds that are 0.65–3 mm x 0.5–1.7 mm, elongated or oval-shaped ( Figures 2f , 5a,c and 6d,f– l ), hanged on the inner wall of the ovary by a 0.08–0.27 mm wide funiculus ( Figures 5e and 6d–e ). A micropyle-like depression 0.15 × 0.36 mm is seen on a seed ( Figure 5a,d ). Figure 1. Siltstone slabs bearing Nanjinganthus . All bars are 1 cm long. (A) Six flowers (1-6) on the same slab, and an associated triangular leaflet with parallel venation. PB22227. (B) Several flowers on the same slab. 1–3 are shown in detail in Figures 2f and 6d,e . PB22226. (C) Several flowers (1-8) on the same slab and the associated Nilssonia parabrevis (top). PB22220. (D) Several flowers (1-6) on the same slab. 1–3 are shown in detail in Figures 2h and 3a–c . PB22224. (E) Many flowers on the same slab. Some of the numbered ones are shown in detail in later figures. PB22222a. (F) A slab with numerous flowers. PB22221. (G) A slab almost fully covered with flowers. PB22228. DOI: https://doi.org/10.7554/eLife.38827.003 The following figure supplement is available for figure 1: Figure supplement 1. The type fossil locality of Nanjinganthus , Nanjing in China and isotopic dating. DOI: https://doi.org/10.7554/eLife.38827.004 Figure 2. Flowers of Nanjinganthus preserved in different states and their details. Bar = 1 mm except otherwise annotated. (A) Numerous flowers preserved on a single slab. Some of the numbered ones are detailed in later figures. PB22222B. Bar = 1 cm. (B) Numerous coalified flowers on the same slab. Some of the numbered ones are detailed in Figure 3d–e . PB22223. Bar = 1 cm. (C) Bottom view of Flower 1 in Figure 2a , showing five sepals (s) and five petals (p) with longitudinal ribs. PB22222B. (D) Bottom view of Flower 2 in Figure 2a , showing four sepals (s) and four petals (p) with longitudinal ribs. PB22222B. (E) Bottom view of the flower in Figure 3f , showing a sepal (s) and three petals (p) radiating from the center, which is obliquely broken to show the relationship among the sepals and petals as in Figure 2j . PB22278. (F) Top view of Flower 1 in Figure 1b with sepals (s), petals (p), and seeds (arrow, enlarged in Figure 6h ) inside the receptacle. PB22226. (G) Side view of a flower bud (Flower 1 in Figure 2b ) with longitudinal ribs (arrows) on the sepals (s) and petals (p). PB22223. (H) Side view of Flower 1 in Figure 1d , showing a receptacle (h), perianth (black arrows), and a dendroid style (white arrow). PB22224. (I) Side view of Flower 15 in Figure 1e , without sepals or petals. PB22222a. Bar = 1 mm. (J) Detailed view of the flower shown in Figure 2e , showing the arrangement of three petal bases (1-3) inside the sepals (s). These petals bases correspond to the three petals (1-3) in Figure 2e . PB22278. DOI: https://doi.org/10.7554/eLife.38827.005 The following figure supplement is available for figure 2: Figure supplement 1. Frequently observed palynomorphs associated with Nanjinganthus . DOI: https://doi.org/10.7554/eLife.38827.006 Figure 3. Individuals of Nanjinganthus . Bar = 1 mm except otherwise annotated. (A–C, PB22224) (A) Flower 2 in Figure 1d (before the dégagement), showing the petal (1) and style (2) still embedded in the sediments. (B The same flower as in Figure 3a , after dégagement, showing the exposed dendroid style (white arrow) and petal (1), and the scale (sc) on the side of receptacle. (C) Detailed view of the style shown in Figure 3b with faint striations (arrows). Bar = 0.5 mm. (D–E) Flower 2 in Figure 2b after and before the organic material of the sepals (white arrows) and petals (black arrows) were removed for cuticle analysis. PB22223. (F) Bottom view of a flower before processing. Internal details are shown in Figure 2e,j . PB22278. DOI: https://doi.org/10.7554/eLife.38827.007 The following figure supplement is available for figure 3: Figure supplement 1. Fossil plants associated with Nanjinganthus . DOI: https://doi.org/10.7554/eLife.38827.008 Figure 4. Nanjinganthus flowers preserved in various orientations and states. Bar = 1 mm except otherwise annotated. (A) An oblique longitudinally split flower (Flower 11 in Figure 1e ) with scales (sc), sepals (s), and petals (p). PB22222a. (B) Alongitudinally split flower (Flower 12 in Figure 1e ) with sepals (s) and petals (p). PB22222a. (C) Integral surface of an ovarian roof with a scar (arrow) left by a broken off style, from the flower shown in Figure 5h . PB22279. Bar = 0.5 mm. (D) Bottom view of a flower (Flower 14 in Figure 1e ) with three sepals (s) and five petals (p) visible. PB22222a. (E) One of the sepals in Figure 4d , showing longitudinal ribs forking (arrow). PB22222a. (F) One of the petals in Figure 4d , showing longitudinal ribs. PB22222a. (G) Side view of a flower, showing scales (sc) on the ovary side and connate bracts (b) at the bottom. PB22229. (H) Detailed view of the connate bracts (b) and scales (sc) in Figure 4g . Note the outline (white line) of the fused bracts. PB22229. (I) The locule surrounded by the ovary wall (arrows) of the flower shown in Figure 4d . PB22222a. DOI: https://doi.org/10.7554/eLife.38827.009 The following figure supplement is available for figure 4: Figure supplement 1. Fossil plants associated with Nanjinganthus . DOI: https://doi.org/10.7554/eLife.38827.010 Figure 5. In situ seeds and flowers. Bar = 1 mm except otherwise annotated. (A) Aseed (outlined) inside the ovary of Flower 16 in Figure 1e . Note the oboval micropyle (black arrow) and funiculus (white arrow). PB22222a. Bar = 0.2 mm. (B) Detailed view of the funiculus (between the arrows) of the seed in Figure 5a . PB22222a. Bar = 0.1 mm. (C) Aseed (detailed in Figure 6i ) inside the ovary of Flower 7 in Figure 1e . PB22222a. (D) Detailed view of the oval micropyle (arrows) of the seed in Figure 5a . PB22222a. Bar = 0.1 mm. (E) Aseed (arrow, detailed in Figure 6d–e ) inside the receptacle in Flower two in Figure 1b . PB22226. (F, G) Two facing parts of the same flower (Flower 10 in Figure 1e ). PB22222a. (H) Top view of a flower with organicallypreserved sepals (s), petals (p) and integral ovarian roof (fr), which is detailed in Figure 4c . PB22279. (I) Side view of a longitudinally split flower with scales (sc) on ovary side, sepals (s), petals (p) and partially preserved style (arrow). PB22489. (J) Detailed view of basal portion of the style (between arrows) arrowed in Figure 5i , with faint longitudinal striations. PB22489. Bar = 0.2 mm. (K) Detailed view of the narrowing base (between arrows) of the rightpetalin Figure 5i . PB22489. Bar = 0.5 mm.(L) Detailedviewofasepalin Figure 5i . PB22489. Bar = 0.2 mm. DOI: https://doi.org/10.7554/eLife.38827.011 The following figure supplement is available for figure 5: Figure supplement 1. Flowers of a living angiosperm and its details. DOI: https://doi.org/10.7554/eLife.38827.012 Figure 6. Dendroid style, in situ seeds, and details of flowers. PB22222a, Bar = 1 mm except otherwise annotated. (A) Alongitudinally split flower (counterpart of Flower 10 in Figure 1e , the same as in Figure 5f–g ) showing the sepal (s) and petals (p), style base (white arrow), and an unknown organ (black arrow). (B) Detailed view showing the pedicel (lower arrow) terminating at the bottom of the ovary in Figure 6a . Note the level of ovarian roof (upper arrow). Bar = 0.5 mm. (C) Detailed view of the basal portion of the style marked by white arrow in Figure 6a . Bar = 0.5 mm. (D) Aseed (white line) hanging by its funiculus (between arrows) on the ovarian wall of the Flower 2 in Figure 1b . PB22226. Bar = 0.5 mm. (E) Detailed view of the funiculus (between arrows) of the seed in Figure 6d . PB22226. Bar = 0.1 mm.(F) Top view of Flower 8 in Figure 1e with sepals and petals surrounding the ovary containing two seeds (s). Note the residue (arrows) of the ovarian roof. (G) Detailed view of one of the oval seeds (s) inside the ovary in Figure 6f . Bar = 0.2 mm. (H) Two seeds (white line), one overlapping the other, inside the ovary shown in Figure 2f . PB22226. Bar = 0.2 mm. (I) An oval seed (white line) inside the ovary of Flower 7 in Figure 1e . Bar = 0.2 mm. (J) Detailed view of Flower 1 in Figure 1g , showing seeds within ovary. PB22228. (K) Detailed view of three seeds (1-3) inside the ovary of the flower shown in Figure 6j . PB22228. Bar = 0.5 mm. (L) Top view of a flower showing petals (p), sepal (sp), seed (s) visible under the ovarian roof (fr). PB22222d. (M) Detailed view of the unknown organ (staminode?) marked by the black arrow in Figure 6a . Bar = 0.5 mm. DOI: https://doi.org/10.7554/eLife.38827.013 Figure 7. The flowers and their internal details. (A-C) (E-I) stereomicroscopy; (D), micro-CL. Bar = 1 mm except otherwise annotated. (A) Aflower carefully dégaged to expose the details of the gynoecium. Note the petals (p) and a style (arrow) in the center. PB22282. (B) Detailed view of the style in Figure 7a , showing its connection (arrows) to the ovarian roof (fr). PB22282. Bar = 0.5 mm. (C) Distal portion of the same style as in Figure 7b , showing its connection with the ovarian roof (fr) and dendroid form with lateral branches (arrows). PB22282. Bar = 0.5 mm. (D) Micro-CL slice 1169 showing a perianth element (black arrow) and branches (white arrows) of the style, embedded in sediments and thus invisible to naked eyes, of Flower 4 in Figure 1e . PB22222a. (E–I) PB22281. (E) Side view of an organically-preserved flower with sepals (s) and petals (p). Note the dark organic material in the ovary (o) and some sepals. The foreground portion of the receptacle has been removed (compare with Figure 7i ), to show the details in Figure 7f– h . (F) Detailed view of the receptacle/ovary in Figure 7e . Note the ovarian roof (fr) preventing the outside (above) sediment (yellow color) from entering the ovarian locule. Bar = 0.2 mm. (G) Detailed view of the solid organically-preserved ovarian roof (fr) with integral outer (upper arrow) and inner (lower arrow) surfaces. Bar = 0.1 mm. (H) Bottom portion of the flowerin Figure 7i , showing subtending bracts (br, arrows). Bar = 0.5 mm. (I) The flowerin Figure 7e , before removing the foreground portion of the ovary. DOI: https://doi.org/10.7554/eLife.38827.014 Holotype Figure 2d ( PB22222B ). Isotypes Figure 6a,f ( PB22222a ), Figure 7e–i ( PB22281 ), Figure 5h ( PB22279 ). Specimens PB22222-PB22229 , PB22236 , PB22238 , PB22241-PB22243 , PB22245-PB22247 , PB22256-PB22260 , PB22278-PB22282 , PB22489 . Figure 8. Details of the sepal and petal. (A-B) stereomicroscopy; (C) (E-G) fluorescence light microscopy; (D) TEM; (H) SEM. Bar = 1 mm except otherwise annotated. (A) Apetal with a narrowing base. PB22280. (B) A partial petal from the Flower in Figure 3d–e , with the longitudinal rib (to the left) forkingat thebase (arrow) andtherib-freelaminarareatotheright. PB22223. (C) Elongatedepidermalcells of thepetalin Figure 8b. PB22223. Bar = 0.1 mm. (D) Transmission electron microscope view showing the cuticle (left, light color) of a petal. PB22223. Bar = 2 µm. (E) Elongated epidermal cells not in strict longitudinal files in the laminar portion of the petal in Figure 8b. Note the two newly formed epidermal cells (arrow). PB22223. Bar = 0.1 mm. (F) Ribs with elongated epidermal cells (left and right) alternating the between region with less elongated cells (middle) of the petal in Figure 8b . PB22223. Bar = 0.2 mm. (G Elongated (above) andisodiametric (below) epidermalcellsonthesepalof Flowerin Figure 3d–e . PB22223. Bar = 0.1 mm. (H) Astoma on the bract of the flower (marked by white arrow in Figure 2h ). PB22224. Bar = 5 µm. DOI: https://doi.org/10.7554/eLife.38827.015 Etymology dendrostyla , for ‘tree-like’ ( dendri -) and ‘style’ (- stylus ) in Latin. Remarks The receptacle is ‘the axis of a flower on which the perianth, androecium and gynoecium are borne’ ( Stevens, 2018 ). This is the definition followed here. The important characteristic of the receptacle in Nanjinganthus is its cup form, a form frequently seen in more derived angiosperms according to the APG system. Adendroid style is seen in ten flowers (four in PB22224, Figures 2h and 3a–b ; four in PB2222a, Figures 2i , 5f–g , 6a and 7d ; one in PB22282, Figure 7a–c ; one in PB22489, Figure 5i–j ). The repeated occurrences of such an unexpected feature in the specimens of Nanjinganthus underscore its truthful existence. The dendroid-form distal portion of the gynoecium may be branched stigmas in Nanjinganthus . But it is possible that these lateral appendages on the style are actually pollen sac complexes, as are similarly attached on the style in extant Malvaceae ( Judd et al., 1999 ) . We have performed a meticulous fluorescence microscopic examination of this structure and found no trace of pollen grains, reducing the possibility that these lateral branches are clusters of pollen sacs, which is the case seen in some angiosperms ( Malvaceae ). Abranched distal projection is apparently lacking in all known gymnosperms, but it has been seen some derived angiosperms, such as Passifloraceae, Poaceae and Euphorbiaceae ( Heywood, 1978 ). One of the advantages of a branched style is the increased receptive area, which is conducive to anemophilous pollination. The occurrence of such feature in Nanjinganthus might suggest that Nanjinganthus had yet not established a close cooperation with animals (insects). However, it is noteworthy that this feature is not seen among extant basal angiosperms sensu APG ( Chase et al., 2016 ). Considering the extremely early age of Nanjinganthus , we refrain from correlating Nanjinganthus with assumed derived taxa ( Malvaceae and Rosaceae). We hope the future research may shed more light the nature of this part of Nanjinganthus . Figure 9. Petal and details of Nanjinganthus . (A-C) light stereomicroscopy; (D) (H) SEM; (E-G) (I-K) fluorescence light microscopy. PB22223. Bar = 1 mm except otherwise annotated. (A) Side view of Flower 3 in Figure 2b , showing the arrangement of the petals (p) and sepal (s). (B) The same flower as in Figure 9a . Note that some organic material of the petal has been removed for detailed observation. (C). Margins (arrows) of the petal (p) with cuneate base and their relationship to the sepal (s). (D) The petal removed from Figure 9a . SEM. Bar = 0.5 mm. (E) Cellular details of the petal in Figure 9d Bar = 0.5 mm. (F) Elongated epidermal cells arranged in files, enlarged from Figure 9e . Bar = 0.2 mm. (G) Isodiametric epidermal cells in the laminar area portion of the petal in Figure 9e . Bar = 0.1 mm. (H) Afragment of the sepal seen in Figure 9a . Bar = 0.5 mm. (I) Cellular details of the sepal in Figure 9h . Bar = 0.2 mm. (J) Elongated epidermal cells arranged in files on the sepal in Figure 9i . Bar = 0.1 mm. (K) Isodiametric epidermal cells on the laminar area of the sepal in Figure 9a . Bar = 0.1 mm. DOI: https://doi.org/10.7554/eLife.38827.016 Figure 10. Cuticular details of Nanjinganthus . A, D-E, Fluorescence light microscopy; B-C, F, SEM. PB22223. (A) Elongated epidermal cells in longitudinal files in the middle portion of the petal in Figure 8b. Bar = 0.1 mm. (B) Elongated epidermal cells on the rib of the petal in Figure 8b. Bar = 50 µm. (C) Apossible stoma on the petal shown in Figure 8b . Bar = 2 µm. (D) Elongated epidermal cells in files on the sepal of flower in Figure 3d–e . Bar = 0.2 mm. (E) Isodiametric epidermal cells on the sepal of flower in Figure 3d–e . Bar = 0.1 mm. (F) Isodiametric epidermal cells on the sepal of flower in Figure 3d–e . Bar = 20 µm. DOI: https://doi.org/10.7554/eLife.38827.017 We have not seen any trace of the carpels typical of Magnoliales, which were previously believed by some to represent ancestral angiosperms. The seeds are physically enclosed by the cup-form receptacle and ovarian roof in Nanjinganthus . This constitutes the foundation based on which we justify our interpretation of Nanjinganthus as an angiosperm. The lack of carpel typical of Magnoliales cannot prevent Nanjinganthus from being an angiosperm as many angiosperms are actually ‘acarpellate’ ( Heads, 1984 ; Sattler and Lacroix, 1988 ). It is noteworthy that, at least in some of basal angiosperms such as Nymphaea ( Nymphaeales ) ( Taylor, 1991 ; Taylor, 1996 ) and derived angiosperms such as Cactaceae ( Boke, 1964 ), the ovary is inferior and the seeds are attached to the ovarian walls. Whether the ovaries in these taxa share similar derivation pathway is a question worthy of further investigation. Four terms are used to describe the foliar parts in Nanjinganthus , namely, bract, scale, sepal, and petal. These terms are used according to the following demarcations and definitions. Bracts designate the foliar parts subtending the ovary. The scales are the foliar parts attached to the sides of the ovary. The sepals are those foliar parts attached to the rim of the receptacle with their whole bases. And the petals are foliar parts with narrowing bases attached to the receptacle rim and inside the sepals. Similar occurrence of bracts, sepals and petals is seen in some extant flowers ( Figure 5 —figure supplement 1 ). The enclosure of the seeds is fulfilled by the cup-form receptacle from the bottom and the structure here-called ‘ovarian roof’ (preserved complete in Figures 4c , 5h and 7e–g , but partially preserved in Figures 2f , 5c and 6f,j,l ) from the above. The intact ovarian roof is clearly seen in the side view ( Figure 7f–g ) and in surface view ( Figures 4c and 5h ), in the latter case the seeds inside ovary are fully eclipsed by the ovarian roof. The ovarian roof is partially lost in Figure 6l , in which a central portion of the ovarian roof broke off revealing one of the seeds inside the ovary. The ovarian roof is almost completely lost (but still with some of its residue) in Figure 6f , and finally fully lost in Figures 2f and 6j–k , in which the seeds are plainly visible. This series of varying preservation status of ovarian roof suggests that the ovarian roof has fully enclosed the ovules in its original status, and the loss of ovarian roof and exposure of seeds are artifacts due to preservation. We cannot recognize the maturity of the ovules/seeds in Nanjinganthus , the length about 1 mm suggests that they are most likely to be seeds rather than ovules, therefore we prefer to use the term ‘seed’ rather ‘ovule’ throughout this paper. The number of seeds in Nanjinganthus is variable. According to our observation, it may be one (not shown), two ( Figure 6f–i ), or even three ( Figure 6j–k ).