National Geographic - Plants Kingdom Plantae National Geographic - Plants

Kingdom Plantae What are plants? most are autotrophs eukaryotic have cell walls containing cellulose mostly land dwelling organisms they are the foundations of almost all ecosystems.

Plants Non-flowering Flowering 1 seed-leaf 2 seed-leaves Spore-bearing Naked seeds Monocots Dicots Gymnosperms No roots with roots Mosses Ferns

Evolution of Plants ancestors of modern day plants were aquatic organism similar to green algae. to grow on land, plants have developed: an embryo – reproductive structure which develops directly into a plant. ability to stand upright and reach for the sun tissues to transport water, nutrients and wastes. strategies to reduce water loss strategies to disperse seeds without relying on water currents. flowering plants are the youngest in plant evolution.

Alternation of Generations most plants have a life cycle that alternates between diploid and haploid forms. diploid (2 sets of chromosomes – 1 from each parent) haploid (1 chromosome set)

Classification of Plants: there are 5 major groups of plants: green algae mosses and relatives ferns and relatives seed plants flowering plants

Green Algae – modern relatives of plant ancestors many species are found in shallow fresh water – edges of ponds Mosses and Relatives – seedless non-vascular plants (Bryophytes) grow close to the ground in damp locations where can easily obtain water. no seeds or stems – no rigid support structures in cell walls, so can’t grow tall. non-vascular – can’t transport water or nutrients within. male and female gametes are produced in separate reproductive structures - sperm have flagella and swim through water to the eggs.

Spore-producing capsule Mosses

Ferns and Relatives – seedless vascular plants have vascular structures to carry water. gives advantage: can grow taller – reach the sunlight vascular structures (veins) connect shoots above ground to roots below seedless: reproduce much like mosses – sperm swims to egg on a film of water on the underside of the plant.

Gymnosperms – seed plants conifers (pine, fir, cedar, ginko) ‘naked seeds’ – not protected or enclosed in an ovary. seeds are plant embryos packaged in a protective coat along with a food supply. pollen grains are small male gametophytes that contains cells that develop into sperm. wind carries the pollen grains to female cones – where eggs develop.

Angiosperms – flowering plants reproductive structures are flowers 2 groups: monocots and dicots ovaries within flowers completely protect the seeds. gametophytes of angiosperms develop within the flowers flowers have many adaptations to disperse pollen and seeds. insects, animals, birds (and wind) all transfer pollen from one flower to another. once pollination occurs the ovary develops into a fruit – the ripened ovary of a flower. fruits are a good way to disperse seeds: if ingested, the seed survives and drops elsewhere burrs stick to animal fur. maple keys are suited to wind dispersal coconuts are well suited to water dispersal

Flowering Plants Monocotyledons Dicotyledons