Unit 7 Plants Ch. 24 Reproduction of Seed Plants

Structure of Flowers  Flowers are reproductive organs composed of 4 kinds of specialized leaves: sepals, petals, stamens, & carpals

Sepals & Petals  Sepals - green leaves that enclose the bud before it opens, & they protect the flower while it is developing  Petals - often brightly colored, found just inside the sepals –Attract insects & other pollinators to the flower

Stamens & Carpels  Stamen - the male parts, consist of an anther & a filament  Filament - a long, thin stalk that supports the anther  Anther - found at the tip of each filament, where pollen grains are formed

Stamens & Carpels  Carpels - (pistils) - the female parts, consists of an ovary, style, & stigma  Ovary - contains 1/more ovules where eggs are produced  Style - stalk connecting the ovary to the stigma  Stigma - top of the style, where pollen grains land

Pollination  Most gymnosperms & some angiosperms are wind pollinated, whereas most angiosperms are pollinated by animals

Seed & Fruit Development  As angiosperm seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds

Seed Dispersal  Dispersal by Animals –Seeds dispersed by animals are typically contained in fleshy, nutritious fruits

Seed Dispersal  Dispersal by Wind & Water –Seeds dispersed by wind or water are typically lightweight, allowing them to be carried in the air or to float on the surface of the water

Seed Dormancy  Dormancy - when the embryo is alive but not growing  Environmental factors such as temperature & moisture can cause a seed to end dormancy & germinate

Seed Germination  Germination - early growth stage of the plant embryo

Vegetative Reproduction  Vegetative reproduction - type of asexual reproduction  Vegetative reproduction includes the production of new plants from horizontal stems, from plantlets, & from underground roots

Vegetative Reproduction  Stolons - long, trailing stems that produce roots when they touch the ground –Ex.) strawberry plants

Plant Propagation  In plant propagation, horticulturists use cuttings, grafting, or budding to make many identical copies of a plant or to produce offspring from seedless plants

Plant Propagation  Cutting - cut part of the plant stem & plant it in the ground  Grafting - when a piece of stem or bud is cut from a parent plant & attached to another plant –The cut piece is called the scion

Plant Propagation  Budding - when buds are used as scions

Agriculture  Most of the people of the world depend on a few crop plants, such as wheat, rice, & corn, for the bulk of their food supply

Agriculture  Between 1970 & 2000, the amount of corn grown per acre in the US increased more than 60%