I II III IV Evolution A evolved from spore bearing plants known as progymnosperms B seeds 1 protect and feed embryo a integument 1 extra layer of sporophyte tissue 2 hardens into seed coats C two types of gametophytes 1 male a pollen grains b dispersed by wind or a pollinator c external water not needed 2 female a embryo sac b develop within an ovule c enclosed within sporophyte tissue Phyla of Extant Seed Plants A gymnosperms naked seeds 1 Coniferophyta 2 Cycadophyta 3 Gnetophyta 4 Ginkgophyta B angiosperms flowering plants 1 Anthophyta Gymnosperms A naked seeds 1 ovule is exposed on a scale at pollination B lack flowers and fruits Angiosperms A flowering plants 1 ovules are enclosed in diploid tissue at pollination 2 carpel a modified leaf that covers seeds b develops into fruits B flower morphology 1 primordium develops into a bud at the end of a stalk called the pedicel 2 pedicel expands at the tip to form a receptacle to which other parts attach 3 whorls a circles of flower organization b from outer to inner c sepals d petals e stamens androecium 1 has a pollen bearing anther and a filament stalk f gynoecium 1 carpels that contain the female gametophyte 4 carpels a ovary 1 contains ovules 2 later develops into fruit b stigma 1 tip where pollen lands c style 1 stalk C life cycle 1 megaspore mother cell undergoes meiosis a produces four megaspores b one megaspore divides mitotically other three disappear 1 produces eight haploid nuclei two groups of four 2 embryo sac a eight nuclei in seven cells b one from each group of four migrates to center 1 polar nuclei may fuse c egg 1 one cell in group closest to micropyle 2 other two are synergids d antipodals 1 three cells at other end 2 no function 3 pollen a diploid microspore mother cells in anthers undergo mitosis 1 produces four haploid microspores b binucleate microspores become pollen grains 4 pollination a transfer of pollen from anther to stigma b may or may not be followed by fertilization c pollen grains form a pollen tube that grows toward embryo sac d generative cell 1 one of the two pollen grains that lags behind 2 divides to produce two sperm cells e double fertilization 1 pollen tube enters embryo sac 2 one sperm joins with egg to form diploid zygote 3 other sperm joins with two polar nuclei to form triploid endosperm a provides nutrients to embryo D seeds 1 importance a growth of embryo stays dormant under unfavorable conditions b protect young plant c provide food for embryo d dispersal of embryo 2 seed coat a most of the embryo s metabolic activities stop once it forms b germination cannot take place until water and oxygen reach the embryo 1 different plants require different things for germination to occur a tough cones that only open when exposed to fire b water can dissolve inhibitory chemicals from seed coat c pass through intestines of animals E fruits 1 mature ovaries carpels a ovary begins to develop into fruit during seed formation b pericarp ovary wall has three layers 1 exocarp 2 mesocarp 3 endocarp 2 fruits may develop without seed development 3 types of fruits a simple 1 single carpel b aggregate 1 multiple carpels c multiple 1 multiple flowers 4 contain three genotypes a fruit and seed coat are from prior sporophyte generation b developing seed contains remnants of gametophyte generation c embryo represents next sporophyte generation Coniferophyta A largest and most familiar phylum B uses 1 timber 2 paper C locations 1 colder and drier regions of the world D examples 1 pines 2 spruces 3 firs 4 cedars V 5 cypress E pines 1 leaves a tough need like b grow in clusters c have a thick cuticle and recessed stomata 1 reduce water loss d canals with resin to prevent insect and fungal attacks 2 reproduction a male gametophytes pollen grains develop from microspores in male cones by meiosis b two ovules develop on each scale of female cones c each ovule contains a megasporangium 1 becomes the female gametophyte d pollen grains go between open scales and are drawn down into micropyle Scales then close 1 two sperm go between each scale e female gametophyte develops a year later f pollen tube is digesting its way to the egg g 15 months after pollination pollen tube reaches archegonium and releases its contents 1 one sperm unites with the egg and becomes a zygote 2 other sperm degenerates h female cones are larger than male cones and have woody scales Cycadophyta Cycads A grow slowly B sporophytes resemble palm trees C largest sperm cells of all organisms D tropical and subtropical regions Gnetophyta A only gymnosperms with vessels in xylem B three genera 1 Welwitschia 2 Ephedra 3 Gnetum Ginkgophyta A only one living species remains 1 Ginkgo biloba B dioecious 1 male and female reproductive structures develop on different trees C flagellated sperm VI VII VIII