Plant Diversity and Classification

Study Notes

Plant Diversity

Kingdom Plantae: eukaryotic, multicellular, autotrophic, and has cellulose cell walls.
Plants live on land and water and are divided into three categories: non-vascular, vascular seedless, and vascular seed plants.

Non-Vascular Plants

Bryophytes (mosses): small, non-vascular, and rely on diffusion for nutrient uptake.
Must live in moist, humid habitats, and need water for reproduction.

Vascular Plants

Vascular seedless plants: ferns, which have a transport system and can grow bigger.
Vascular seed plants: cone plants (gymnosperms) and flowering plants (angiosperms).

Algae

General term for autotrophic, non-vascular, unicellular or multicellular organisms that are mainly aquatic.
Three groups of algae: Chlorophyta (green), Rhodophyta (red), and Phaeophyta (brown).
Chlorophyta: every green plant evolved from green algae, and they have the green color from photosynthetic pigment chlorophyll.
Examples of Chlorophyta: Chlamydomonas (unicellular), Spirogyra (filamentous), Volvox (colonial), and Ulva (foliaceous).

Origins of Plants

Plants evolved from chlorophyta in water and then adapted to land.
Chlorophyta have the same photosynthetic pigments as modern plants.

Adaptations to Land

Absorption system (roots or rhizoids) required for plants to survive on land.
Waxy cuticles prevent desiccation but also prevent gas exchange, so stomata (small openings) allow gas exchange to occur.
Pollen, a male gamete, evolved to allow for gamete transportation on land.

Plant Support System

In water, buoyancy means woody support systems are unnecessary.
On land, xylem and phloem provide structural support, transport water and dissolved minerals, and sugars up and down the plant.

Alternations of Generation

Basis of all plant and fungal life cycles.
Haploid (n) generation: one copy of every chromosome.
Diploid (2n) generation: two copies of every chromosome.
Mitosis: nuclear division resulting in an exact copy of itself.
Meiosis: cell division that reduces chromosome number, halves ploidy.
Spores: haploid reproductive cells used in asexual reproduction.
Gametes: haploid reproductive cells used in sexual reproduction.
Fertilization: fusion of two gametes, forms a zygote.
Gametophyte: haploid generation that produces egg and sperm.
Sporophyte: diploid generation that produces spores.

Life Cycle of Bryophytes

Dominant generation is gametophyte.
Sporophyte is small and delicate on gametophyte.
Need water for reproduction, so they live in moist, humid habitats.

Life Cycle of Ferns

Sporophyte (2n) is dominant.
Gametophyte is small but independent.
Prothallus: mature gametophyte.
Antheridium: male part of the gametophyte.
Archegonium: female part of the gametophyte.
Sorus: unique to ferns, a cluster of plant reproductive bodies.
Sporangium: shell that bursts open to release spores when conditions are dry.

Description

Test your knowledge of the kingdom Plantae, including non-vascular plants, vascular seedless plants, and vascular seed plants. Learn about the characteristics of different plant groups and their classification.