Colonization of Land

Characteristics of Fungi

• Heterotrophs like animals - cannot carry out photosynthesis

  • Utilize external digestion and absorb materials in their hyphae

  • The above ground “parasol” is only a tiny part of the actual organism

• Eukaryotic

• Cell walls made of chitin

• DO NOT store carbohydrates as starch

• Reproduce sexually or asexually

Fungal Body

• composed of hyphae - network of branched filaments adapted for absorption

  • essential for nutrient absorption, growth, reproduction, structure

• Mycelium - hyphae woven into a mat-like structure

General Life Cycle of Fungi

Plasmogamy - union of cytoplasm from two different haploid mycelia, occurs first

Karyogamy - fusion of haploid nuclei to form diploid cells, occurs hours/days/or centuries later

Origin of Fungi

Microsporidia - unicellular parasites, identified as early diverging group of fungi (primitive fungi)

Groups of Fungi

• Cryptomycetes - parasites of other fungi

• Microsporidians - parasites with harpoon like spores

• Chytrids - fungus attacking frogs and salamanders

• Zoopagomycetes - parasites or symbionts of animals

• Mucuromycetes - molds implicated in food storage

• Ascomycetes - sac fungi which produce ascocarps

• Basidiomycetes - club fungi; decomposers and mushrooms

Seedless Plants

• adapted to life on land

• Plants on land needed structural support and protection from drying out

• Carbon dioxide more available

• Fewer things to eat plants at first

• First plants colonized high humidity areas

New Plant Structures for Land

• Alternation of generations

  • Diploid Sporophyte (2n) to produce haploid spores

  • Haploid Gametophyte (n) to produce haploid gametes

• Apical meristem in shoots and roots

• Waxy cuticle protects leaves from drying out

• Cell walls with lignin to strengthen them

Gymnosperms

• No flowers or fruits

• “Naked” seeds that are not enclosed in chambers

• Often bear cones for seed production

• Primarily wind pollinated

• Less sophisticated vascular system than angiosperms

• Smaller, more ancient

Angiosperms

• Enclosed seeds, protected within a fruit which develops from the ovary of a flower

• Flowers/fruits

• Diverse pollination methods, wind/water/insect

• More sophisticated vascular system

• Largest and most diverse group of plants

• Cluster of flowers called an inflorescence

• Double fertilization to give endosperm

General Structure of a Flower

• Sepals (sterile) - enclose the unopened flower

• Petals (sterile) - attract pollinators with bright colors

• Stamens (fertile) - produce pollen

• Carpels (fertile) - produce ovules, term pistil refers to single or two or more fused carpels

Seed Plants

Always see the sporophyte form. Only non-vascular plants have the haploid gametophyte as the most important form.

Heterosporus Plants

• Produce two kinds of spores

• Megasporangia

  • Produce megaspores which produce female gametophytes

• Microsporangia

  • Produce microspores which produce male gametophytes

Monocots vs Dicots

Gymnosperms_

• came first

• naked seeds on scales on cones

• ovule but no ovaries

• never fruits or flowers

• Male and Female cones

  • Microsporocyte (male)

  • Megasporocyte (female)

• ex. Cycads, ginkgophytes, Gnetophytes, conifers

Conifers

• Cone bearing

• Male and female cones

• Needle-like leaves

• No fruits or flowers

• ex. Pine tree, Douglas Fir

Cycads

• Resemble palms but have cones

• Large compound leaves

• ex. Sago Palm

Ginkgophytes

• High resistance to pollution

• Male and female trees

• ex. Ginkgo Baloba

Gametophyte - Sporophyte Relationships