bio 126 nature study & conservation plants & fungi
TRANSCRIPT
Bio 126 Nature Study & Conservation
Plants & Fungi
Plants: Evolved from green algae Have evolved more terrestrial modes of
reproduction. Are the primary producers on land Determine how many animals can be
supported in an ecosystem Limited by water, sun, nutrients (like
Nitrogen), weather extremes, soil types,etc.
Green Algae at seashore
Green Algae Have aquatic (swimming) gamete = sperm
and egg Lack transport tissues - (like wood)
No Xylem – carries water No Phloem – carries sugar
No true roots or leaves Some can dry out at low tide
Green Algae gave rise to: Mosses and liverworts, which gave rise to: Ferns and related plant groups which gave
rise to: Conifers and related plant groups which
gave rise to: Angiosperms (flowering plants) which
have form two groups: Monocots Dicots
Mosses No hard parts (no xylem , no phloem) Still has sperm and eggs (needs a film of
water to reproduce) Disperse by spores: single plant cells that
can dry out, move in air currents Have no roots or leaves Many can dry out
Ferns and related groups Still have sperm and eggs Still disperse with spores Have Xylem, phloem
Can grow taller, like tree ferns Can pull water from deep in the soil
Gymnosperms - Conifers “naked” seeds – a protected embryo for
dispersal, no spores Pollen – male gamete, dry in air - wind Many have needles Some can tolerate very dry, cold conditions Have male and female cones
“pine cone” is female cone with seeds Cone size may be linked to seed size Protected, no water needed for fertilization
Angiosperms: Flowering plants Coevolved with pollinators
Flowers structure evolved to attract, work with pollinators
Seeds form inside a fruit Fruit coevolved with dispersal agents:
animals, wind
The flower
Sepals Petals Stamens (male)
Anther - pollen Filament
Carpel (female) Stigma Style Ovary - fruit Ovule-eggs- seeds
Figure 30.13 Flower-pollinator relationships
A flower pollinated by honeybees.This honeybee is harvesting pollen and Nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping Mechanism that arches the stamens over the bee and dusts it with pollen, some of which will rub off onto the stigma of the next flower the bee visits.
(a) A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Common adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate.
(c)A flower pollinated by hummingbirds. The long, thin beak and tongue of this rufous hummingbird enable the animalto probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive.
(b)
Butterfly Flower
Butterfly Flower
Butterfly Flower
Hummingbird
Bee flower
Fungi
Fungal Characteristics:
Feed by Absorptive Nutrition Tubular cell shape, called Hyphae
Septate or aseptate hyphae Chitin cell walls Reproduce by making spores
Sexual & Asexual No sperm or egg
Nutrition and Habits Saprobes- decomposers
exoenzymes Parasitic fungi- Mutualistic Fungi-
Molds – rapidly growing, asexually reproducing fungi
Most also have non-mold sexual stages The mycelia of these fungi grow as
saprobes or parasites on a variety of substrates
Often breakdown simple sugars etc.
Yeasts- unicellular fungi growing in liquid substrates Form new cells by budding Some can sexually reproduce, many form asci Some can ferment sugar to alcohol
Mycorrhizae Mutualism of Tree root and
fungus. Gives tree water and minerals
(desert plants) and fungus gets carbohydrates.
Make most of your forest mushrooms
Plant growth withoutmycorrhizae is often stunted
Mycorrhizae
Pathogenic Fungi Attack plants
Rusts -red spores on multiple hosts Smuts –yeast like fungi rot plant Aflatoxins, Ergot –on rye.
Attack People – Mycosis Ringworm, athlete’s foot San Joaquin Valley Fever Yeast, lung infections
Attack insects, fish, etc.
Examples of fungal diseases of plants
(a) Corn smut on corn (b) Tar spot fungus on maple leaves (c) Ergots on rye
Lichens Symbiosis of
Phycobiont, algae / cyanobacteria Mycobiont - fungi.
Not individual organisms Primary colonizers of new land in
succession, and in tundra areas Soredia asexually reproduce lichen
Fungi often reproduce on their own.
Fig. 31.17
Three growth forms:1. Crustose – flat on
stones2. Foliose- leaf-like as
in picture3. Fruticose- upright
growing
Phycobiont in inner layers protected by fungi on top and bottom
(a) A fruticose (shrub-like) lichen
(b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichens