Evolution and Origin of Gymnosperms:
– Over 1,000 living gymnosperm species exist.
– Gymnosperms originated during the Early Carboniferous period.
– A genome duplication event around 319 million years ago contributed to gymnosperm radiation.
– Fossil evidence suggests pollination by scorpionflies and Kalligrammatid lacewings.
– Gymnosperms are seed-producing plants and are considered primitive plants.
Characteristics and Adaptations of Gymnosperms:
– Gymnosperms have needle-like or scale-like leaves.
– They usually have cones for reproduction.
– They are adapted to cold and dry environments.
– Gymnosperms have a dominant sporophyte generation.
– They have vascular tissue for nutrient transport.
Importance and Uses of Gymnosperms:
– Gymnosperms like pine, fir, spruce, and cedar are used for lumber, paper, and resin.
– Some gymnosperms have medicinal properties.
– They are used in landscaping and horticulture.
– Gymnosperms contribute to the Earth’s oxygen production.
– Gymnosperms play a crucial role in ecosystems.
Distribution and Habitat of Gymnosperms:
– Gymnosperms are found worldwide.
– They dominate in colder climates.
– Conifers are the most widespread gymnosperms.
– Some species thrive in tropical regions.
– Gymnosperms can adapt to diverse habitats.
Conservation and Threats to Gymnosperms:
– Many gymnosperm species are endangered.
– Habitat destruction threatens gymnosperms.
– Climate change impacts gymnosperm populations.
– Conservation efforts include seed banks.
– Protection of gymnosperm habitats is crucial for biodiversity.
The gymnosperms (/ˈdʒɪmnəˌspɜːrmz, -noʊ-/ ⓘ JIM-nə-spurmz, -noh-; lit. 'revealed seeds') are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος (γυμνός, gymnos, 'naked' and σπέρμα, sperma, 'seed'), literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, Ginkgo. Gymnosperm lifecycles involve alternation of generations. They have a dominant diploid sporophyte phase and a reduced haploid gametophyte phase which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to (the paraphyletic group of) all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.
Gymnosperm Temporal range:
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Various gymnosperms. | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Spermatophytes |
Clade: | Gymnospermae |
Living orders | |
The gymnosperms and angiosperms together constitute the spermatophytes or seed plants. The spermatophytes are subdivided into five divisions, the angiosperms and four divisions of gymnosperms: the Cycadophyta, Ginkgophyta, Gnetophyta, and Pinophyta (also known as Coniferophyta). Newer classification place the gnetophytes among the conifers. Numerous extinct seed plant groups are recognised including those considered pteridosperms/seed ferns, as well other groups like the Bennettitales.
By far the largest group of living gymnosperms are the conifers (pines, cypresses, and relatives), followed by cycads, gnetophytes (Gnetum, Ephedra and Welwitschia), and Ginkgo biloba (a single living species). About 65% of gymnosperms are dioecious, but conifers are almost all monoecious.
Some genera have mycorrhiza, fungal associations with roots (Pinus), while in some others (Cycas) small specialised roots called coralloid roots are associated with nitrogen-fixing cyanobacteria.