* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Seedless Vascular Plants
Plant secondary metabolism wikipedia , lookup
Photosynthesis wikipedia , lookup
Plant stress measurement wikipedia , lookup
Plant tolerance to herbivory wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Plant use of endophytic fungi in defense wikipedia , lookup
Venus flytrap wikipedia , lookup
History of botany wikipedia , lookup
Plant nutrition wikipedia , lookup
History of herbalism wikipedia , lookup
Plant morphology wikipedia , lookup
Plant breeding wikipedia , lookup
Plant physiology wikipedia , lookup
Flowering plant wikipedia , lookup
Plant ecology wikipedia , lookup
Historia Plantarum (Theophrastus) wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Sustainable landscaping wikipedia , lookup
+ Seedless Vascular Plants Ferns and Their Relatives + Introduction Once plants like bryophytes became adapted to living on the land, evolution continued to select for plants that had traits favorable to this strange, dry territory. Today’s descendants of these early plants reveal the traits that made them successful. + Successful Land Traits Better control of internal water concentration. Plants developed thicker cuticles, providing better waterproofing. Plants also developed stomata that could open and close became the norm, rather than pores like those in bryophytes that stay open all the time. + Successful Land Traits Development of roots to increase water and mineral uptake from the soil. Scientists think roots evolved in ancient vascular plants from stems that grew along or just under the surface of the soil. Once these surface branches started growing under the surface of the soil, they were exposed to different conditions than the branches above the ground. + Successful Land Traits Plants whose underground branches were able to absorb water had an advantage over other plants, leading to the evolution of a more root-like structure over time. + Successful Land Traits Internal vascular tissue for conducting water and sugar throughout the plant body. In particular, the development of waterconducting tracheids helped change the way plants grow. Because of their strong, lignified cell walls, tracheids provide greater structure and support to plants, enabling plants to grow more erect. + Successful Land Traits A more erect, branched pattern of growth. Branching let the early land plants produce multiple sporangia per plant, increasing their chances of reproductive success. Once plants started producing leaves, branching allowed plants to spread their leaves out so that they didn’t shade each other, maximizing the capture of sunlight for photosynthesis. + Successful Land Traits The evolution of leaves, allowing better capture of light. Small simple leaves called microphylls, evolved in a group of plants called lycophytes. Microphylls are simple leaves with a single unbranched vein of vascular tissue. In addition, larger, more complex leaves called megaphylls developed in almost all other vascular plants. + Successful Land Traits Megaphylls have branching veins. Scientists think megaphylls evolved when leaf tissue grew around small, flat clusters of branches, joining them together in a leaf-like structure. Over time, the branches became the branching veins within the leaf. + Successful Land Traits The combination of these new traits gave plants much better control over their internal water content, increased their reproduction, and improved their ability to effectively harvest light for photosynthesis. + Successful Land Traits Another important characteristic of plants that first appears in the seedless vascular plants is heterospory. Heterosporous plants produce two different types of spores. Megaspores are larger and grow into female gametophytes. Microspores are smaller and grow into male gametophytes. + Successful Land Traits Within the plant kingdom, heterospory evolved may times, so scientists think it must have given plants a real advantage. Many plant groups today, including the very successful flowering plants, are heterosporous. + Devonian Periods + Successful Land Traits After these evolutionary innovations occurred, groups of land plants expanded and evolved into many different species, creating a burst in plant diversity between 417 and 354 million years ago (the Devonian Period) that eventually led to the development of the first forests between 354 and 290 million years ago (the Carboniferous period). + Carboniferous Forest + Successful Land Traits Over these time periods, the relationship between the gametophyte and sporophyte generation changed. Sporophytes became the more dominant plant generation. Gametophytes got progressively smaller and more protected by the sporophyte. + Successful Land Traits Botanists think that the reason sporophytes became dominant is that all the adaptations that allow plants to survive in dry environments evolved in sporophytes. + Successful Land Traits All seedless vascular plants have several characteristics in common: The sporophyte is the dominant phase of the life cycle, but the gametophyte is independent and photosynthetic. The sporophyte makes and disperses spores from sporangia. The gametophyte makes gametes in gametangia. They require water for sexual reproduction so the sperm can swim to the egg. The sporophyte has vascular tissue, a cuticle, and stomates. + Phylum Psilotophyta: the whisk ferns Whisk ferns loosely resemble small, green whisk brooms. Whisk fern structure: Evenly No forked stems which are photosynthetic roots or leaves Enations (tiny, green leaf-like outgrowths on the stems) present Step 2 Step 6 Step 3 Step 5 Step 4 Phylum Psilotophyta: the whisk ferns Step 7 + Step 1 + Phylum Psilotophyta: the whisk ferns Reproduction: 1. Small sporangia are borne on short stubby branches. 2. Meiosis occurs in sporangia producing meiospores. 3. Meiospores germinate slowly on soil or bark of tree ferns. 4. Gametophytes found beneath the soil are very small (2mm x 6mm). + Phylum Psilotophyta: the whisk ferns 5. Archegonia and antheridia are produced on this colorless gametophyte. 6. Fertilization occurs in the archegonium. 7. Sporophyte develops from the zygote.