Unit 7 Plants Ch. 24 Reproduction of Seed Plants.

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%