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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 lonchilifoliaŠimůnek (1996a), Pl. XIV, fig. 4foto ZŠ14
Alethopteris lonchilifoliaŠimůnek (1996a), Pl. XIV, fig. 2foto ZŠ13
Alethopteris lonchitica ZŠ790
Alethopteris lonchitica ZŠ788
Alethopteris lonchitica p4652
Alethopteris lonchitica ZŠ799
Alethopteris lonchiticain prep. Šimůnek (2020)fig. 4C ZŠ848
Alethopteris lonchitica ZŠ845
Alethopteris obligua ZŠ511
Alethopteris refractaŠimůnek (1996a), Pl. XV, fig. 1foto ZŠ17
Alethopteris refractaŠimůnek (1996a), Pl. XV, fig. 2 ZŠ18
Alethopteris refractaŠimůnek (1996a), Pl. XV, fig. 1foto ZŠ16
AlethopterisŠimůnek (1996a), Pl. XXI, fig. 8. ZŠ29
Alethopteris WA193
Alethopteris WA311
Alethopteris WA182
Alethopteris WA310
Alethopteris ZŠ793
Alethopteris urophylla BrongniartŠimůnek (1996a), Pl. XI, fig. 1foto ZŠ10
Alethopteris urophylla BrongniartŠimůnek (1996a), Pl. XIV, fig. 1foto ZŠ12
Virtual museum of the Czech Geological Survey, www.geology.cz, (C) Czech Geological Survey, 2011, v.0.99 [13.12.2011]