Vascular Seed Plants Angiosperms

Angiosperms Flowering Plants Largest group of plants on Earth All species produce a flower of some type Use insects, animals and wind for pollination Largest group of plants on Earth 250 000 species

Angiosperm Seeds Vary in size Often enclosed e.g. coconut to banana! Often enclosed usually in a fruit. Can remain dormant for long periods of time until environmental conditions are right for germination Often spread using animals or insects

Angiosperm Seeds This is the most successful group of plants. Turn and talk…..Why??? Enclosed seed protects seed in early development Flower/Fruit Encourages pollination and seed dispersal by insects or animals Angiosperms evolved along with insects

Angiosperm Groups Arranged in two groups: Cotyledon = seed leaf Monocotyledons “Monocots” Dicotyledons “Dicots” Fig 29.1 in text Cotyledon = seed leaf First leaf to appear

Monocots – Key features Embryo one cotyledon Root Vascular tissue forms a ring Stem Vascular tissue scattered

Monocots – Key features Leaves Leaves have parallel veins. Flower parts are in multiples of three.

Dicots – Key Features Embryo Root Stem Two cotyledons Vascular tissue forms a cross Stem Vascular tissue arranged in a ring

Dicots – Key Features Leaves Flower Leaves have ‘net-like’ veins. Parts in multiples of four or five.

Monocot or Dicot?

Plant Structure 2 Main Systems Root system Shoot system Functions: Water and mineral absorption, anchorage and support, carbohydrate storage, production of hormones Main Organs: Roots Shoot system Functions: Photosynthesis, gas exchange, reproduction Main organs: Stems, Leaves, Flowers/Fruits

Structure cont’d Systems connected by vascular tissue Tissues for the transport of materials throughout the plant body. Xylem Conduct water and minerals from roots to leaves Dead at maturity Phloem Conducts glucose from the leaves to rest of the plant Alive at maturity

Reproduction: Flowers Sexual reproductive structure In alternation of generations, still a diploid structure Is it a girl or a boy? Male produce the mobile gametes Females produce the non-mobile gametes

Reproduction Flowers cont’d Dioecious male and female reproductive organs are carried on separate individual plants of the same species. Monoecious have both male and female reproductive organs borne on a single plant.

Reproduction Flowers cont’d Male Reproductive Organs Stamen Anther contains tissue that gives rise to pollen grains Filament Pollen Male gamete

Reproduction Flowers cont’d Female Reproductive Organs Carpel Stigma Style Ovary hollow area that encloses one or more ovules. Ovule contains an embryo sac, the structure that gives rise to the female gamete, the egg. In most flowers, the carpels are fused together to form a pistil.

Flower Structure (Fig. 29.16) Receptacle base of the flower specialized region of the stem Calyx consisting of a ring of sepals Can be many colours or small green and leaf-like

Flower Structure (Fig. 29.16) cont’d Corolla composed of petals primary function of attracting insects to serve as pollinators Stamen Carpel

Angiosperm Lifecycle Fig. 29.17

Angiosperm Lifecycle cont’d Anther Many mother cells divide by meiosis to create haploid microspores Called Pollen Each grain of pollen contains two haploid nuclei

Angiosperm Lifecycle cont’d Ovule Mother cell divides by meiosis to form 4 haploid megaspores Only one megaspore develops into an egg in each ovule. Ovule also contains a diploid nucleus

Angiosperm Lifecycle cont’d Pollination Transfer of pollen from anther to stigma Pollen attaches to the stigma, and travels down the style to the ovary Self – fertilization is possible in plants Doesn’t increase genetic variability, so often the stigma is not ‘ready’ at the same time as the pollen

Angiosperm Lifecycle cont’d Fertilization Pollen has two haploid nuclei Angiosperms exhibit double fertilization Fertilization 1 Fusion of microspore and egg Produces diploid zygote Fertilization 2 Fusion of microspore and a diploid cell Produces endosperm Has 3 sets of chromosomes = triploid (3N) Nutritive tissue of seed

Angiosperm Lifecycle cont’d Seed Development Zygote  embryo Endosperm  nutritive tissue Ovule  mature seed. Ovary fruit.

Seed dispersal mechanisms Hooks and spines Attach to and are carried by animals. Explosion Throws seeds from parent Wind Lightweight seeds, parachutelike or winglike structures

Seed dispersal mechanisms cont’d Water Seeds contain air pockets to allow them to float. Fleshy fruits Nutritious for animals Pass unharmed through the digestive system and are deposited in the animal’s waste (ideal fertilizer)