Chapter 17 summary from quizlet.docx

**Chapter 17 summary from quizlet** **Evolution of Vascular Plants** **Bryophytes and Vascular Plants** - Both bryophytes and vascular plants share multicellular embryos and form a monophyletic lineage called embryophytes, with common ancestors in charophycean-algal-like organisms. -...

**Chapter 17 summary from quizlet** **Evolution of Vascular Plants** **Bryophytes and Vascular Plants** - Both bryophytes and vascular plants share multicellular embryos and form a monophyletic lineage called embryophytes, with common ancestors in charophycean-algal-like organisms. - They exhibit an alternation of heteromorphic generations, with bryophytes having free-living gametophytes and nutritionally dependent sporophytes, while vascular plants have more prominent, ultimately free-living sporophytes. - Bryophytes emphasize the gamete-producing generation and require water for motile sperm, while vascular plants have specialized parts like roots, stems, and leaves for various functions. **Early Vascular Plant Sporophytes and Evolution** - Early vascular plants initially had dichotomously branched axes without roots and leaves, which later evolved into differentiated plant organs like roots for anchorage, stems for support, and leaves for photosynthesis. - The root system anchors the plant and absorbs water and minerals, while the shoot system raises leaves to sunlight for photosynthesis. - Vascular plants have a vascular system that conducts water and minerals, with plant cells organized into tissues and further into dermal, vascular, and ground tissue systems. **Vascular Plants: Ecological Success and Diversity** - Vascular plants dominate terrestrial habitats due to their adaptations, with seven phyla having living representatives and several extinct vascular plant phyla. - By the Devonian period, vascular plants were numerous and diverse, lacking seeds and relying on water for reproduction. - The chapter discusses characteristic features of vascular plants and five phyla of seedless vascular plants. **Seedless Vascular Plants** - Dominant from Middle Silurian to Middle Devonian (425-370 million years ago). - Monilophytes, Lycophytes, and Progymnosperms became dominant groups. - Dominated from Late Devonian to Carboniferous period. - Originated around 375-290 million years ago. **Seed Plants** - Originated in Late Devonian period, 380 million years ago. - Evolution of new lines by Permian period. - Gymnosperms dominated land floras until 100 million years ago. **Flowering Plants** - Identified at least 135 million years ago. - Became abundant within 30-40 million years. - Currently dominant globally. **Organization of the Vascular Plant Body** **Plant Body Structure** - Plant cells are organized into tissues, further into dermal, vascular, and ground tissue systems present in all plant organs. - Root, stem, and leaf structures differ based on the distribution of vascular and ground tissue systems, with the vascular system conducting water and minerals. - Primary growth involves apical meristems and extends the plant body, while secondary growth thickens stems and roots through lateral meristem activity. **Tracheary Elements and Vascular Tissues** - Tracheary elements in xylem are conducting cells with lignified wall thickenings, providing insights into vascular plant interrelationships. - Tracheids, the main water-conducting cells in most vascular plants, support stems and enable upright habits due to lignin in their walls. - Vessel elements, principal water-conducting cells in angiosperms, evolved independently in various vascular plant groups, showcasing convergent evolution. **Primary and Secondary Growth** - Primary growth forms the main part of the plant body through primary tissues initiated by apical meristems. - Secondary growth thickens stems and roots via lateral meristem activity, producing secondary vascular tissues like cork cambium and periderm. - Tracheary elements, including tracheids and vessel elements, play crucial roles in water and mineral conduction, supporting plant structures and habits. **Types of Vascular Plant Steles** - Protostele is the simplest and oldest type, consisting of a solid cylinder of vascular tissue found in extinct seedless vascular plants, lycophytes, and roots. - Siphonostele features a central pith surrounded by vascular tissue, providing structural support and nutrient transport in vascular plants. **Siphonostele** - Consists of a solid cylinder of vascular tissue. - Phloem surrounds or intersperses xylem. - Leaf gaps mark vascular strand departure from stem. - Parenchyma cells fill leaf gaps. - Leaf traces in seed plants differ from leaf gaps. **Eustele** - Characterized by discrete strands around a pith. - Eusteles evolved from protosteles. - First appeared among progymnosperms. - Siphonosteles evolved independently. - Roots likely evolved from lower parts of ancient plants. **Leafs as Stem Appendages** - Principal lateral stem appendages. - Arise from apical meristem. - Two leaf types: microphylls and megaphylls. - Microphylls have single vascular strand. - Megaphylls associated with siphonosteles or eusteles. **Reproductive Systems** **Homospory in Vascular Plants** - Found in most ferns, horsetails, and some lycophytes. - Basic condition for heterospory evolution. - Can produce bisexual gametophytes. - Fern sporophytes are often heterozygous. - Cross-fertilization mechanisms in ferns promote genetic diversity. **Heterospory in Vascular Plants** - Production of two spore types in different sporangia. - Microspores and megaspores produce male and female gametophytes. - Heterosporous plants develop within the spore wall. - Homosporous plants\' large gametophytes are independent. - Plant evolution involved gametophyte and sporophyte elaboration. **Phyla of Seedless Vascular Plants** - Key groups: Rhyniophyta, Zosterophyllophyta, Trimerophytophyta. - Extinct by end of Devonian period. - Progymnospermophyta may be ancestral to gymnosperms and angiosperms. - Early vascular plants dominated from Middle Silurian to Middle Devonian. - Monilophytes, Lycophytes, and Progymnosperms dominated from Late Devonian to Carboniferous period. **Phylum Rhyniophyta** **Characteristics and Origin** - Originated from the Middle Silurian, 425 million years ago. - Extinct in the Middle Devonian, 380 million years ago. - Simple, dichotomously branching stems with terminal sporangia. - Named after fossils from Rhynie, Scotland. **Rhynia gwynne-vaughanii** - Marsh plant with upright, dichotomously branched aerial system. - Short branches often bore sporangia. - Absence of leaves, aerial axes served as photosynthetic organs. **Internal Structure of R. gwynne-vaughanii** - Similar to many vascular plants with epidermis and photosynthetic tissue. - Center composed of solid strand of xylem surrounded by phloemlike cells. - Tracheids share features with moss water-conducting cells. **Aglaophyton major** - Originally known as Rhynia major, now Aglaophyton major. - Consists of extensive dichotomously branched rhizome system with limited upright stems. - Considered an intermediate stage in vascular plant evolution. **Phylum Zosterophyllophyta** **Characteristics and Evolution** - Found in Early to Late Devonian period (408-370 million years ago). - Leafless, dichotomously branched, covered with a cuticle. - Named after modern seagrasses of the genus Zostera. **Internal Structure and Relation to Lycophytes** - Kidney-shaped sporangia borne laterally on short stalks. - Ancestors of lycophytes. - Internal structure similar to rhyniophytes with centripetal differentiation. **Phylum Trimerophytophyta** **Evolution and Characteristics** - Likely evolved from rhyniophytes. - Larger, complex plants than rhyniophytes or zosterophyllophytes. - Branching is complex with massive vascular strand. - Xylem differentiates centrifugally. **Trimerophytes** - Larger and more specialized than rhyniophytes, lack leaves. - Homosporous with complex branching. - Phylum name means \'three-parted plant.\' **Phylum Lycopodiophyta** **General Overview** - Extends back to Devonian period with 10-15 genera and 1200 species today. - Basal split between lycophyte clade and euphyllophytes in Early to Middle Devonian. **Club Mosses and Characteristics** - Contain all but two genera of living lycophytes. - Possess microphylls, a characteristic of the phylum. - Tree lycophytes were dominant in coal-forming forests during the Carboniferous period. **Distribution and Structure** - Extends from Arctic to tropics, with most tropical species being epiphytes. - Sporophytes consist of a branching rhizome with aerial branches and roots. - Sporophylls are usually spirally arranged. **Morphology and Reproduction** - Sporophytes structure: rhizome with aerial branches and roots, protostelic stems and roots. - Sporophyll arrangement: spirally, opposite, or whorled; homosporous with sporangia on fertile microphylls. - Gametophytes: bisexual, green masses or subterranean structures; archegonia and antheridia maturation takes 6 to 15 years. - Fertilization process: water-dependent, biflagellated sperm to archegonium, zygote development, independent sporophyte growth. - Genera in the US and Canada: Huperzia, Lycopodium, Diphasiastrum, Lycopodiella; differences in sporophyll arrangement, rhizomes, and chromosome numbers. **Variety in Genera** - Huperzia: fir mosses, Lycopodium: tree club mosses, Diphasiastrum: club mosses and running pines, Lycopodiella: species with technical differences. - Spike Mosses (Selaginellaceae Family): Selaginella genus with 750 species, tropical habitat, some dormant in deserts, e.g., Selaginella lepidophylla. - Male and female gametophytes in Selaginella, heterosporous nature, male gametophytes lack chlorophyll, female gametophytes may develop chloroplasts. - Isoetes: heterosporous, specialized cambium, some obtain carbon from sediment, lack stomata, and have a thick cuticle. - Isoetaceae (Quillworts and Tree Lycophytes): Isoetes genus, aquatic or dry plants, short stem with quill-like microphylls, each leaf a potential sporophyll. **Phylum Monilophyta** **Ferns and Horsetails** - Diversity: over 12,000 species, 3/4 in tropics, 380 in US and Canada, 1000 in Costa Rica. - Variety in species: Lygodium climbing fern, tree ferns like Cyathea, Botrychium unique vascular cambium, Eusporangia vs. Leptosporangia. - Spore characteristics: nourished by tapetum, catapult-like discharge, homosporous vs. heterosporous nature in water ferns and extinct species. - Psilotopsida Class: Ophioglossales and Psilotales orders, Botrychium and Ophioglossum genera, leaf and fertile segment variations. - Psilotales Genera: Psilotum in the US, Tmesipteris in Australia, simple plants with tiny leaves and no roots. **Evolutionary Groups and Classification** - Tropical Marattiopsida: ancient group with fossil records from the Carboniferous period, resemblance to familiar fern groups, extinct tree fern Psaronius. - Polypodiopsida Classification: 10,500 species, leptosporangiate, unique features like siphonostelic rhizomes, megaphyll fronds, and subterranean gametophytes. - Rhizome characteristics in temperate ferns, true root production in embryo, megaphyll fronds as the prominent sporophyte part. **Fern Morphology and Reproduction** **Rhizome and Frond Structure** - Ferns in temperate regions have siphonostelic rhizomes producing new leaves annually. - Fronds are compound, divided into leaflets or pinnae attached to the rachis. - Young leaves exhibit circinate vernation, uncoiling due to rapid growth mediated by auxin. - Leaves are megaphylls, the most conspicuous part of the sporophyte. - Ferns are the only seedless vascular plants with well-developed megaphylls. **Sporangia and Taxonomy** - Sporangia are found on leaves\' margins, in clusters called sori. - Sori are covered by indusia, which shrivel when sporangia are ripe. - Sorus characteristics are crucial in Polypodiopsida taxonomy. - Sori appear as yellow, orange, brownish, or blackish lines, dots, or patches. **Gametophytes and Fertilization** - Fern spores give rise to free-living, potentially bisexual gametophytes. - Antheridia and archegonia develop on the prothallus\'s ventral surface. - Gametangia appearance is genetically controlled and influenced by special chemicals. - Water is essential for multi-flagellated sperm to reach eggs. **Sporophyte Production and Diversity** - Sporophyte is the perennial stage in ferns, while gametophyte is short-lived. - Some fern species reproduce via vegetative outgrowths called gemmae. - Eusporangiate ferns like Trichomanes speciosum can have long-lived gametophytes. - Ferns with strap-shaped gametophytes reproduce distinctively through gemmae. **Water Ferns and Horsetails** **Salviniales and Marsileaceae** - Water ferns consist of Salviniales order and Marsileaceae and Salviniaceae families. - Marsilea leaves resemble a four-leaf clover, with sporosocarps for reproduction. - All water ferns are heterosporous, unique among living ferns. - Marsileaceae alone has about 50 to 70 species. **Equisetophytes and Equisetum** - Equisetophytes date back to the Devonian period, represented by Equisetum today. - Equisetum horsetails are recognized for jointed stems, scale-like leaves, and ribbed internodes. - Aerial stems of Equisetum have complex anatomical structures with hollow pith. - Equisetum reproduces homosporously through sporangia borne in groups along sporangiophores. **Common Local Ferns and Their Characteristics** **Deer Fern, Western Sword Fern, Lady Fern** - Deer Fern has evergreen, once-pinnate leaves and dark leaf stalks. - Western Sword Fern features large, scaly rhizomes and sharp-toothed leaflets. - Lady Fern has feathery fronds tapering at both ends and elongated, curved sori. - Oak Ferns, Western Maidenhair Fern, Bracken Fern - Oak Ferns have broadly triangular, hairless fronds and uncovered, round spore cases. - Western Maidenhair Fern spreads by rhizomes and has triangular, hairless fronds. - Bracken Fern exhibits large, upright triangular fronds growing from underground rhizomes. - Spiny Wood Fern - Spiny Wood Fern has triangular to oblong-triangular fronds with sparsely glandular pinnae. - Fronds are 2- to 3-pinnate, with the lowest pinnae longer than the upper ones.