Kingdom Plantae Plant Morphology

Ancestor = Charophytes  member of the green algae Plant Evolution Ancestor = Charophytes  member of the green algae Algae had to come first  build up of oxygen in atmosphere  led to formation of the ozone layer Land plants = embrophytes – multicellular dependent embryonic stage

Evidence that supports this idea: Homologous chloroplasts Similarity in characteristics d/t common ancestry Biochemical similarity Similarities in cytokinesis Sperm cell ultrastructure Genetic relationships Similar chlorophyll a & b 20 – 26% cellulose in walls Cell plate formation is similar

Problems associated with movement to land Desiccation Gas exchange Support of multicellular structures Spore or seed dispersal Reproduction 1.Avoid or tolerate dessication – had no roots nor vascular tissues 2. Occurred via diffusion through cell walls  water loss  live in cool, damp places 3. Stay close to ground  poor competitors for light 4. Had to rely on wind currents 5. Transfer gametes  live in wet places (flagellated sperm cells)

Found in all land plants Derived characteristic – found in some algae but not in charophytes

Alternation of generations Two Generations: Sporophyte stage Diploid stage Sporo = spore (n) plant sporopollenin Spores produced via meiosis Sporangium  sporocytes (2n) Sporangium: protection in land plants (not seen in algae) Sporopollenin: prevent dessication & microbial attack

Alternation of generations con’t. Two Generations: 2. Gametophyte a. haploid stage b. gameto = gamete plant c. gametes produced via MITOSIS

Sporophyte dominates life cycle Monocots Dicots Angiosperms ovary Gymnosperms no ovary seeds Cryptogams spores vascular Bryophytes nonvascular land Sporophyte dominates life cycle

Dominant during first 100 miy during plant evolution - Means they lack xylem & phloem ( the conducting tissues)

Gametangia = structures where gametes are produced Bryophytes Gametangia = structures where gametes are produced Archegonia - egg cells Antheridia – sperm cells * Sporophyte cannot live independently Multicellular organ  Act as protective jackets & prevent gametes from drying out FIND ON GAMETOPHYTE OR SPOROPHYTE? GAMETES PRODUCED VIA MEIOSIS OR MITOSIS

Moss plants – gametophyte & sporophyte generations SMALL TEETH AT END OF CAPSULE  HELP DESSIMINATE SPORES

PAGE 581, FIGURE 29.8 SPOROPHYTE GETS NUTRITION FROM GAMETOPHYTE

The Liverworts (Hepatophyta) - Marchantia sp.

The Hornworts (Anthocerophyta) Anthoceros sp.

Bryophytes con’t Stomata a. openings in leaves that allow for gas exchange

NORMALLY FOUND ON UNDERSIDE OF LEAF

Bryophytes con’t Cuticle (made of cutin) HELPS PREVENT DESSICATION PROTECT AGAINST MICROBIAL PREDATORS

No fundamental difference between above and below ground parts Bryophytes con’t. No fundamental difference between above and below ground parts - 2 cm tall Still have a need for water 5. flagellated sperm b. usually found in moist places

Vascular Plants - Tracheophytes Dominant stage = sporophyte Specialized organs Stems Leaves - megaphyll - microphyll Sporophylls: specialized leaf to house meiosporangia Many cone shaped Homosporous & heterosporous Roots - rhizomes Megaphyll – borad leaves with highly branched veins  more efficient at photosynthesizing Microphyll – needle-like leaf with single vein c. Modified leaves that bear sporangia - homosporous: sporangium produces single type of spore that develops into a bisexual gametophyte (several seedless vascualrs) - heterosporous: sprorangium prouduces megaspor or micorspore  male and female gametophytes respectively, egg and sperm (seeds & few seedless vasculars)

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

Two types of growth – apical meristem a. Primary growth Vascular plants con’t. Two types of growth – apical meristem a. Primary growth b. Secondary growth Sperm still flagellated Maintained stomata & cuticle Growth at tips of stems and roots B. increase in girth

Vascular Plants - Tracheophytes  plants w/ pipes Broken up into two groups: Reproduce by spores Cryptogams: crypto: hidden, gam: sex Reproduce by seeds Gymnosperms: naked seed plants (cones) Angiosperms: seed surrounded by ovary (flowers)

Innovations of the Cryptogams Roots - uptake water, minerals, nutrients, and gases Vascular tissue - xylem & phloem arranged in bundles Division of labor - specialized tissues and organs Lignin - infused in xylem  support against gravity Hormones - regulate plant development

P: Lycophyta C: Lycopodiopsida (microphylls)

P: Lycophyta C: Sellaginellopsida Sellaginella – The resurrection plant l.s. strobilus

P: Psilotophyta * stems only

P: Sphenophyta Equisetum sp. - Horsetail Aerial stem in c.s.

Equisetum gametophyte & sporophyte stages.

Equisteum strobilus (cone: compact group of meiosporangium-bearing structures). Left: whole mount and Right: cross section showing sporangiophore: stem-like structure bearing sporangium (container in which spores are borne).

P: Pterophyta – the ferns Gametophytes

Sori (cluster of meiosporangia) on the underside of sporophylls (specialized leaf that bears meiosporangia) aka fronds.

Sori in c.s. Note – indusium: layer of tissue protecting meiosporangia filled with meiospores. Annulus (head portion of meiosporangia) also present.

Left: fern gametophyte (prothallium) with archegonia and antheridia Left: fern gametophyte (prothallium) with archegonia and antheridia. Right: sporophyte growing out of gametophyte. Rhizoids present.

Vascular Seed Plants Gymnosperms – naked seed plants Angiosperms – flowering plants

Seed plant characteristics Seeds Reduced gametophytes – microscopic - Gametophytes develop from spores retained in sporangia of parental sporophyte protects female gametophyte from environmental stresses - Gametophyte obtains nutrients from sporophytes

Seed plant characteristics con’t. Heterospory Megasporangia: produce megaspores that give rise to female gametophytes egg within ovule Microsporangia: produce microspores that give rise to male gametophytes sperm within pollen

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

Seed plants Purpose of the seed: A. means of dispersal B. Survive unfavorable conditions C. Stores food for embryo D. Protection from predators

Seed plants con’t. Characteristics Maintained: -vascular tissue -cuticles -stomata

Gymnosperms Needle-like leaves Found in moderately cold & dry regions Direct pollination  ovules NOT enclosed in ovaries

dioecious: seeds & pollen produced on different sporophytes P: Cycadophyta dioecious: seeds & pollen produced on different sporophytes strobili: micro and megasporophylls 360 million years old Two major groups Gymnosperms – “naked seed” plants Angiosperms – flowering plants

Phylum: Ginkgophyta Ginkgo biloba – single species in the phylum. i. dioecious ii. male pollen cone w/ 2 microsporangia (whole & l.s.) iii. no seed cone  ovules on end of branches

Phylum: Gnetophyta Welwitschia – found in the deserts of Africa i. dioecious

Ephedra pollen cone: note microsporangia (compound strobilus) Phylum: Gnetophyta con’t. pollen cone: note microsporangia (compound strobilus) Ephedra seed cone: will produce two seeds

Phylum:Coniferophyta

Conifer characteristics largest group of gymnosperms (600 spp.) most are evergreen, monoecious, trees or shrubs needle or scale-like leaves compound seed cones (ovules on cone scales) Simple or clustered pollen cone

Needle-like leaves Curled bracts fasicle (group of needle-like leaves attached to a single shoot) bundled in a papery sheath

Angiosperms Produce seeds and flowers Petals  brightly colored to attract pollinators Dominate the landscape

The anatomy of a flower

Flower anatomy con’t.

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

Pollination

Parallel vein net-like vein Fibrous root tap root Monocots vs. Dicots Mono Dicot 1 cotyledon 2 cotyledons Parallel vein net-like vein Fibrous root tap root Flwr parts in 3 flwr parts in 4-5 Scattered bundles bundles in ring (in the stem)