Kingdom Plantae Lower Plants, Organization, Morphology and Reproduction

Plant Evolution Ancestor = Charophytes  member of the green algae

Problems associated with movement to land 1.Desiccation (dehydration) 2.Gas exchange 3.Support of multicellular structures 4.Reproduction 5.Spore or seed dispersal

Alternation of Generations

Alternation of generations Diploid Full # chromosomes 2n All non-gamete cells Can’t be gametes Human = 46 Haploid ½ # chromosomes n Gametes At fertilization become diploid zygote Human = 23

Alternation of generations Two Generations: 1.Sporophyte stage (spore-plant) a.Diploid stage (2n) b.Produces haploid spores by meiosis c.Spores grow into gametophyte containing male or female repro structures.

Alternation of Generations

Alternation of generations con’t. Two Generations: 2. Gametophyte (n) (gamete plant) a. haploid stage b. Male: has antheridia, makes sperm c. Female: has archegonia, makes eggs d. gametes produced via MITOSIS e. Sperm swim f. Fertilization produces zygote g. Grows into Sporophyte

Alternation of Generations

Bryophytes (nonvascular land plants) Hepatophyta Liverworts Anthocerophyta Hornworts Bryophyta Mosses

The Liverworts (Hepatophyta) - Marchantia sp. Gemmae cups-asexual Female Gametophyte Archegonia

The Hornworts (Anthocerophyta) Anthoceros sp.

Moss plants – Bryophyta gametophyte & sporophyte generations

See fig 27.12, Russell*

Adaptation to Land Problems associated with movement to land 1.Desiccation (dehydration) 2.Gas exchange 3.Support of multicellular structures 4.Reproduction 5.Spore or seed dispersal

Adaptation to Land (desiccation, gas xchge) 1.Stomata: a. Openings in leaf surface b. control H 2 O loss b. allow for gas exchange

Adaptation to Land (desiccation,transport) 1.Stomata: 2.Vascular Structures a. Xylem-H 2 O up from Roots b. Phloem-sugar around

Adaptation to Land (dessication) 1.Stomata: 2.Vascular 3.Cuticle a. H2O proof b. prevents dessication

Cuticle (made of cutin)

Adaptation to Land (support) 1.Stomata: 2.Vascular Structures 3.Support a. Lignin in cell walls b. allows for branching and larger size

Bryophytes No true roots or vascular tissue - 2 cm tall Still have a need for water (Repro)

Vascular Plants Dominant stage = sporophyte (Gametophyte hidden) Specialized organs a.Roots -rhizomes b.Stems c.Leaves

Vascular plants con’t. Branching Some contain lignin a. structural support Vascular tissues a. Xylem b. phloem

Vascular Bundles in Monocot stem

Vascular plants con’t. Two types of growth – apical meristem a. Primary growth b. Secondary growth Sperm still flagellated Maintained stomata & cuticle

Nonseed Vascular Plants LycophytaPsilotophytaSphenophytaPterophyta

LycophytaPsilotophyta Lycopodium sp.Psilotum sp. (microphylls)(stems only)

SphenophytaPterophyta – the ferns Equisetum sp.

Sori on the underside of sporophylls

Vascular Seed Plants Coniferophyta - the gymnosperms Anthophyta - the angiosperms

Seed plants Purpose of the seed: A. means of dispersal of offspring B. Survive unfavorable conditions C. Stores food for embryo D. Protection from predators E. Remember “Seedy Side of Plants”

Seed plants (con’t.) Non-flagellated sperm a.pollen b.Moved by water, wind, insects, and animals c.Forms pollen tube for sperm Egg cells a. Called ovules  located inside the ovary

Seed plants con’t. Reduced gametophyte a. composed only of sperm or egg Maintained: a.vascular tissue, b.Cuticle c.stomata

Gymnosperms A. Needle-like leaves B. Found in moderately cold & dry regions C. Direct pollination  ovules NOT enclosed by tissue of the sporophyte (gym= naked)

Gymnosperm Life Cycle

Gymnosperms – naked seed plants Cycads (Sego palm)Ginkgo biloba Strobili: sporophylls (leaves with sporangia) Phy: Ginkophyta Phy: Cycadophyta

WelwitschiaEphedra Phylum: Gnetophyta

Coniferophyta

Angiosperms 1.Produce flowers, seeds and fruit 2.Petals  brightly colored to attract pollinators 3.Dominate the landscape

The anatomy of a flower

Flower anatomy con’t.

Angiosperms con’t. Pollination 1.Pollen grain lands on stigma and germinates 2.Pollen tube grows down through style into ovary  releases sperm into ovules (egg cells) 3.Mature ovary = fruit 4.Mature ovule = seed

Pollination

Monocots vs. Dicots MonoDicot 1.1 cotyledon2 cotyledons 2.Parallel veinnet-like vein 3.Fibrous roottap root 4.Flwr parts in 3flwr parts in Scattered bundlesbundles in ring (in the stem)