New Characteristics of Seed PlantsNo longer require water for reproductionGametophyte greatly reducedFemale gametophyte is an ovuleMale gametophyte is pollenSeed replace sporesHeterosporousMale and FemaleThe ability of pollen to be dispersed by wind or animals allows the seeded vascular plants to break their ties to waterGametophytes of seed plants develop within the walls of spores retained within tissues of the parent sporophyte.The gametophyte is no longer independentTwo types of spores are seen in the seed plants. They are heterosporous.MegasporesGives rise to the female gametophyteAn ovule containing an eggThe outer layer of the ovule is the integument and the tissue of the ovule is diploidMicrosporesGives rise to the male gametophyteA pollen grain containing spermMicrospores develop into pollen grains which can be dispersed by winds or animals, eliminating the need for water in fertilizationA pollen grain can give rise to a pollen tube that allows for passage of sperm into the female gametophyteThe seed develops from the ovuleThe integuments becomes the seed coatThe zygote becomes the embryoThe seed also contains tissue that acts as food for the new plantThe seeded vascular plants can be divided into two major groupsNon-flowering Plants (Gymnosperms)ConiferophytesThe most successful because of their ability to live under a wide variety of conditionsEvergreens including pine, fir, spruce, cypress, redwood, and cedarCycadophytesHave lag cones and palm-like leavesThrived during the Mesozoic era (dinosaurs)GinkgophytesThe only living species today is the Ginkgo biloba.It tolerates air pollution wellThe fleshy seeds smell rancid as they decayGnetophytesSome are tropical, others live in desertsThree generaGnetumEphedrawelwitschiaThe seeds are referred to as naked seeds, meaning that there is no outer coveringThe stored food in the seed is haploid and arose directly from the female gametophyteLife cycle shows two of the key characteristics of seed plantsPollenDominant SporophyteFlowering Plants (Angiosperms)The seeds have additional covering which is the fruitThe stored food is triploid and arises from a combination of female and male gametophytesMake up the majority of modern land plantsMain characteristicsFlowersSpecialized shoot with modified leaves which are specific for sexual reproductionComplete FlowersMain PartsSepalsModified leaves in angiosperms that help enclose and protect a flower bud before it opensPetalsModified leaves of a flowering plant.Often colored to attract pollinatorsStamensThe male reproductive part and consists of the filament (stalk), which holds the anther.The anther contains the pollen grainsCarpelThe female reproductive part and is a vase shaped structure made up of the stigma, the style, and the ovaryStigma is the top of the vase. It’s a sticky structure designed to catch the pollenStyle is the neck of the vase. The pollen must grown through the style to reach the eggOvary is the bottom of the vase. The ovary contains the ovules, which become seeds. The outer layer of the ovary becomes the fruit.Seeds enclosed in fruitThe main function of the fruit is to aid in seed dispersal.Wind dispersalMechanical dispersalWater dispersalAnimal dispersalBroad leavesAdvanced vascular tissueAngiosperm pollination and Fertilization1. Pollination starts when pollen from an anther lands on a stigma2. The pollen grain grows a tube down through the style towards the ovary3. The 2 sperm cells from the generative cell moves down the tube to the ovary where a double fertilization occursDouble Fertilization:One sperm fuses with the egg cell to form a zygoteThe other sperm fuses with polar nuclei in the primary endosperm cell making this triploid endosperm (3 sets of chromosomes) tissueThe angiosperms include:MonocotsHave one embryonic seed (cotyledons)DicotsPlants that have two embryonic seed leaves (cotyledons)Basil angiosperms (ex: water lilies)MagnolidsEudicotsMonocotsDicotsFlower StructureArranged in groups of 3Arranged in groups of 4 or 5LeavesNarrow with parallel veinsWider with branching netlike veinsVascular TissueScattered vascular bundlesRing of vascular bundlesRootsMany smaller rootsOne main taprootPollenSingle openingThree openingsSeedOne cotyledonTwo cotyledonsThe plant embryo contains the cotyledons (seed leaves)The similarities in the overall seed structure for Flowering and Nonflowering groups includes:EmbryoStored foodSeed coatFlower AnatomyLeaf AnatomyPlant Growth OverviewThe basic design of land plants has two parts: root system and the shoot system.Root SystemThe root is an organ thatAnchors the vascular plantAbsorbs mineral and waterStores organic nutrientsAs a seed begins to grow, the first root is the primary rootIn monocots this primary root is replaced by a fibrous root system composed of many roots about equal sizeIn dicots the primary roots turn into the taproot system, which has one main root that had lateral roots branch offThe epidermis of the root is very thin and has no waxy cuticle. In addition, the epidermis forms roots hairs to increase the surface area. These characteristics make the root very permeable to water.The Shoot SystemAs the shoot of a plant grows ar the apical bud, it gives rise to different specialized tissuesStemsBudsLeavesFlowersAll of the shoot structures come from small groups of cells which are left behind by the apical budThese groups of cells form leaf primordia (leaf producing group) and axillary buds (branch producing group)These groups of cells are clustered at sites of nodes and are usually distributed at regular intervals along the stem. These intervals are known as internodes (the space between two nodes on the same side of the stem)The formation of branches from lateral buds is triggered by hormones (or lack of certain hormones)LeavesLeaves of a plant have two main parts; the blade and the petiole (the leaf stem).Plants have three main tissue systemsDermal Tissue SystemOutside covering, from the protodermTwo tissues make up the dermal tissue systemEpidermal tissueForms the epidermis (skin) that covers the outside of the plantMade up of thin-walled cell with a waxy cuticlePeridermCan replace the epidermis in older woody stems, branches, and trunksMade up of thick-walled cork cellsGround Tissue SystemThe in-between stuff, from the ground meristemVascular Tissue SystemThe pipes, from the procambiumPlant Diversity II: The Evolution of Seed Plants Test 3New Characteristics of Seed Plants- No longer require water for
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