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Gymnosperms

      The gymnosperms are a group of seed-bearing plants that includes conifers, cycads, Ginkgo, and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos (γυμνόσπερμος), meaning "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilized state). Their naked condition stands in contrast to the seeds or ovules of flowering plants (angiosperms), which are enclosed during pollination. Gymnosperm seeds develop either on the surface of scale- or leaf-like appendages of cones, or at the end of short stalks (Ginkgo). The gymnosperms and angiosperms together comprise the spermatophytes or seed plants. By far the largest group of living gymnosperms are the conifers (pines, cypresses, and relatives), followed by cycads, Gnetales (Gnetophyta, Ephedra and Welwitschia), and Ginkgo (a single living species).

Source: http://en.wikipedia.org/wiki/Gymnosperms
Alethopteris bohemica YA1276
Alethopteris bohemicaŠimůnek (1989), Pl. 1, fig. 1foto YA1273
Alethopteris bohemica YA1280
Alethopteris bohemicaŠimůnek (1989), Pl. II, fig. 3. YA1283
Alethopteris bohemicaŠimůnek (2022), PL. 1, Fig. 7 ZŠ879
Alethopteris bohemicafoto YA1274
Alethopteris bohemicaŠimůnek (1989), Pl. I, fig. 2foto YA1275
Alethopteris davreuxiiŠimůnek (1996a), Pl. I, fig. 9 ZŠ1
Alethopteris decurrensŠimůnek (1996a), Pl. III, fig. 2 ZŠ3
Alethopteris decurrensŠimůnek (1996a), Pl. III, fig. 1 ZŠ2
Alethopteris distantinervosa (Wagner, 1968)Šimůnek (1988): Pl. III, fig. 1; Šim.-Cleal (2002) Fig. 2e,f; in prep. Šimůnek (2020)fig. 4A ZŠ850
Alethopteris grandiniŠimůnek (1996a), Pl. IV, fig. 7 ZŠ6
Alethopteris grandiniŠimůnek (1996a), Pl. IV, fig. 6 ZŠ5
Alethopteris grandiniŠimůnek (1996a), Pl. IV, fig. 4 ZŠ4
Alethopteris grandinioidesAD, Šimůnek (1988) YA1385
Alethopteris idaeŠimůnek (1996a), Pl. VII, fig. 1-4foto ZŠ7
Alethopteris jongmaniiŠimůnek (1996a), Pl. VIII, fig. 2 ZŠ8
Alethopteris lancifoliaŠimůnek (1996a), Pl. IX, fig. 6 ZŠ9
Alethopteris leonensis ZŠ512
Alethopteris lonchilifoliaŠimůnek (1996a), Pl. XIV, fig. 5foto ZŠ15
Virtual museum of the Czech Geological Survey, www.geology.cz, (C) Czech Geological Survey, 2011, v.0.99 [13.12.2011]