Plant Diversity PDF

# Plant Diversity ## The Kingdom Plantae In order to be classified as a plant, an organism MUST be: - Multicellular - Eukaryotic - Cell walls made of cellulose (sugar) - Autotrophic (photosynthesis) ## Plant Life Cycles Plants, like the protists and fungi we've talked about before, go through a...

# Plant Diversity ## The Kingdom Plantae In order to be classified as a plant, an organism MUST be: - Multicellular - Eukaryotic - Cell walls made of cellulose (sugar) - Autotrophic (photosynthesis) ## Plant Life Cycles Plants, like the protists and fungi we've talked about before, go through alternation of generations during their life cycles. - Plants have both a haploid and a diploid stage. - In plants, these stages have special names. - **Gametophyte** - a haploid individual that produces gametes. - These gametes will combine to form the diploid sporophyte. - **Sporophyte** - A diploid individual that produces haploid spores through meiosis. - The spores then grow into gametophytes. ## Evolution of Plants - The first plants evolved from algae. - Algae spend their whole lives in water, while plants evolved to live on land. - In order to survive on land, plants needed to be able to do three things. ## Three Adaptations for Land - Plants need to be able to absorb nutrients from their surroundings. - Plants evolved roots for just this purpose. - The very first plants did not have roots. Instead, they got their nutrients from symbiotic fungi (mycorrhizae). - Plants need to be able to prevent water loss to keep from drying out. - Plants evolved a waxy, watertight covering called a cuticle. - Plants need to be able to disperse (spread) themselves across dry land. - Several ways plants can do this: - Wind - Water - Other organisms ## Plant Groups - Plants evolved to form 4 main groups: - Nonvascular plants - Vascular plants - Nonseed plants - Seed plants - Conifers - Flowering plants - We will look at in terms of seedless plants and seed plants. ## Streptophytes: The Green Plants | | Non Vascular | Vascular | | --------------- | ---------------------- | ----------------------------------- | | Charophytes | | | | | Seedless Plants | Seedless Plants | | | Bryophytes | Lycophytes | | | | Pterophytes | | | | Seed Plants | | | | Spermatophytes | | Liver-worts | Liver-worts | | | Horn-worts | Horn-worts | | | Mosses | Mosses | Club Mosses | | | | Whisk Ferns | | | | | | | | Gymnosperms | | | | Angiosperms | | | | | | | | Quillworts | | | | Horsetails | | | | | | | | Spike Mosses | | | | Ferns | ## Seedless Plants - Seedless plants are the most primitive plants. - They can be divided into two smaller groups: - Nonvascular (bryophytes) - Vascular - The very first plants were nonvascular seedless plants, and vascular plants evolved from there. ## Nonvascular Plants - Bryophytes - These plants do not have vascular tissue (veins) to transport water throughout the organism. - Examples include mosses, liverworts, and hornworts. - Water is transported through the plant by osmosis and diffusion. - This means water moves very slowly and over short distances. - This limits the size of these plants - they simply can't move water far enough quickly enough to grow large. ## Vascular Plants - An important step in the evolution of plants was the development of vascular tissue (veins). - This is what makes it possible for plants to move food and water over great distances, allowing them to grow tall. - The most well-known member of this group are ferns. - Two types of vascular tissue: - **Xylem** - transports water through a plant - **Phloem** - transports food (nutrients and sugars) through a plant ## Seed Plants - Groups - Seed plants are divided into two smaller groups - gymnosperms and angiosperms. - Both of these groups are vascular plants, and they all produce seeds to aid in the survival and dispersal of their offspring. - The difference between the two groups is how they develop their seeds - angiosperms have fruit, while gymnosperms do not. - Gymnosperm = "naked seed" - Angiosperm = "covered seed" ## Gymnosperms - Cone Bearers - Gymnosperms are conifers. - Any plant that does not have its seeds inside of fruit falls in this classification. - Many types of trees, but not all. ## Angiosperms - Angiosperms develop unique reproductive organs known as flowers. - Thus, they are known as the flowering plants. - These attract insects and animals to aid in pollination. - Flowers have ovaries which surround and protect the seed. - After fertilization, these ovaries swell up and develop into fruit. - This aids in dispersal - the plant wants it to get eaten so that it can be carried far distances before getting pooped out. ## Classifying Angiosperms - Angiosperms are divided into two classes based on their seeds - the monocots and dicots. - **Monocots** - have one seed leaf (called a cotyledon) - **Dicots** - have two seed leafs ## Monocots vs. Dicots - Besides the difference in the number of seed leaves, there are other differences between these two groups as well. - Monocots usually have parallel venation, while dicots have net venation. - Monocot flowers tend to have their parts in multiples of 3, while dicot flower parts tend to be in multiples of 4 or 5. - Monocots tend to have fibrous root systems, while dicots tend to have one large taproot.