Introduction to the plant kingdom

What Is a Plant? Plant – multicellular autotroph in which the embryo develops within the mother plant Autotroph – organism capable of producing its own food source Plants are a special kind of autotroph called phototrophs – organisms that use energy from sunlight to create their own food through photosynthesis

Reserve food stored as amylose (starch) What Is a Plant Cont. Photosynthesis – process where energy from sunlight is used to produce sugar (glucose) Reserve food stored as amylose (starch)

Early Aquatic Ancestor Group of aquatic multicellular green algae called Charophytes Closest living species to a possible land ancestor Adaptations that allowed permanent life on land accumulated 475 million years ago

Benefits of Aquatic Environment Plants are surrounded by water so they don’t dry out Water helps support the plant (counters gravity) Plants absorb nutrients from water Sperm is able to swim to egg Plants stay in upper surface near sunlight

Adaptations to Life on Land Problems: Obtaining Minerals Gravity Dryer Environment Reproduction Solutions: Roots absorb water and minerals Lignin and cellulose (sturdy framework) Waxy cuticle and stomata w/ guard cells Pollen containing sperm

Algae & Land Plant Similarities Both contain chlorophylls a and b Have chloroplasts with stacks of thylakoids Store starch in plastids (organelle containing food) Contain cellulose in cell walls Go through Alternation of Generations life cycle

Taxonomy Plants are divided into two groups: Vascular Nonvascular Groups are categorized by the presence or absence of an internal transport system Vascular System – transports water and dissolved materials

Vascular System Xylem Tissue – carries water and minerals upward from roots Phloem Tissues – carries sugars made by photosynthesis from leaves to where they will be stored or used Sap – fluid carried inside the phloem or xylem Vascular Bundles

Plant Cell Types Parenchyma Cells Least specialized Thin, flexible and living Carry out metabolic processes Collenchyma Cells Thicker primary cells Living at maturity Sclerenchyma Cells Thick secondary (cell walls) Dead at maturity

Nonvascular Plants Called Bryophytes Do not have vascular tissue for support or conduction of materials Require a constantly moist environment Can’t grow as tall Materials move by diffusion (cell-to-cell movement) Sperm must swim to egg through water droplets

Nonvascular Plants Includes: 1. Mosses (Bryophyta) 2. Liverworts (Hepatophyta) 3. Hornworts (Antherophyta)

Also called Tracheophytes Contain xylem and phloem Vascular Plants Also called Tracheophytes Contain xylem and phloem Subdivided into two groups: Seedless Vascular Plants Seed Bearing Vascular Plants

Anatomy of Vascular Plant Shoots Found above ground Have leaves attached Photosynthetic part of plant Roots Found below ground Absorb water and minerals Anchor the plant

Plant Growth Plants grow through areas of rapidly dividing, undifferentiated cells called meristems. Apical Meristem : Located at tips of roots and shoots Increase plant length (primary growth) Lateral Meristem: Located at periphery of plant Increase girth (secondary growth)

Seedless vascular Plants Includes: 1. Moss (Lycophyta) 2. Horsetails (Sphenophyta) 3. Whisk Ferns (Psilophyta) 4. Ferns (Pterophyta)

Seed Bearing Vascular Plants Gymnosperms – produce naked seeds in cones Angiosperms – have flowers that produce seeds to attract pollinators

Gymnosperm means “naked seeds” = not enclosed within an ovary Gymnosperms Gymnosperm means “naked seeds” = not enclosed within an ovary Includes: Conifers (Coniferophyta) Cycads (Cycadophyta) Ginkgo (Ginkgophyta)

Produce seeds when egg is fertilized by pollen in the ovary Angiosperms Flowering plants Produce seeds when egg is fertilized by pollen in the ovary Produce fruit to attract organisms that help disperse seeds

Monocots and Dicots Dicots: Monocots: Two cotyledons Angiosperms are subdivided into two groups: Dicots: Two cotyledons Flower parts in multiples of 4’s or 5’s Netted leaf venation Vascular bundles arranged in a ring Monocots: One cotyledon (primary leaf) Flower parts in multiples of 3 Parallel leaf venation Scattered vascular tissue