Early-bird Special
• The following terms refer to alternation of
generation:
– Homosporous (“one type of spore”… . a single type of
spore produces a single type of gametophyte which
produces both male and female gametes)
– Heterosporous (“different spore types”… . one type of
gametophyte produces male gametes while another
type produces female gametes)
Kingdom Plantae
Unifying Characteristics
• Multicellular eukaryotes
• photosynthetic autotrophs
• Chlorophyll A & B
• cell walls of cellulose
• produce gametes w/in a gametangia
• Exhibit alternation of generation with “sporic
meiosis” (figure 33.4)
Note: spores
develop into
gametophyte
Gametophyte
produces gametes
Sporophyte
produces spores!
Zygote produced
by fusion of gametes
Kingdom Plantae
Four Major Steps in Evolution of Land Plants
• Protection from desiccation
– waxy cuticle
– protected gametangia
• male = antheridia
• female = archegonium
• Vascular tissue
• Seeds
• Flowers
Kingdom Plantae
Non-Vascular Plants
• Characteristics
– have waxy cuticles & jacketed gametes
– lack true vascular tissue
– retain flagellated sperm
– dominance of gametophyte (1N) generation
– sporophyte nutritionally dependent on gametophyte
• Three phyla of non-vascular plants
– Hepaticophyta (liverworts)
– Bryophyta (mosses)
– Anthocerotophyta (hornworts)
Is this Liverwort homosporous or heterosporous?
Male gametophyte
Female gametophyte
Gemmae cups are a means of asexual reproduction
in liverworts
Life cycle of moss (fig 33.7)
Flagellated sperm
swims to find egg
Gametophyte (1N)
generation dominates
life history
Sporophyte (2N) generation
is not free-living
Kingdom Plantae
Vascular, Seedless Plants
• Need for vascular system
• Two-part vascular system
– Xylem- water transport
– Phloem- transport organic compounds
Kingdom Plantae
Vascular, Seedless Plants
• Characteristics of vascular, seedless plants
– have vascular tissue, but lack seed
– life cycle dominated by sporophyte generation
– retain free-living gametophyte generation
– retain flagellated sperm
– most groups are ‘homosporous’
• Geologic importance of seedless plants
Kingdom Plantae
Vascular, Seedless Plants
• Four phyla of vascular, seedless plants
– Psilophyta (wisk ferns)
• simplest vascular plant
• lacks true roots or leaves
– Lycophyta (club mosses)
• “resurrection plant” of desert areas
• “quillworts” are simple aquatic plants
– Arthrophyta, the horsetails
• “scouring rushes” due to silica deposits in stems
• lack photosynthetic leaves
• branched photosynthetic stems resemble horse tail
Kingdom Plantae
Vascular, Seedless Plants
– Pterophyta, the ferns
• widely distributed and huge diversity of forms
• “Giant Salvinia” is a floating fern that will cause huge
ecological problems in Texas
Homosporous,
freeliving
gametophyte
Life cycle dominated
by sporophyte
Life cycle of fern (fig 33.13)
Kingdom Plantae - Seed Plants
• First developed some 360 mybp, but quickly
dominated land environment
• Characteristics of seed plants
– dominance of sporophyte (2N) generation
– heterosporous alternation of generation
– gametophyte is parasitic on sporophyte
– pollen replaces flagellated sperm
– developing embryo is packaged into a seed
• Two categories of seed plants
– Gymnosperms (naked seed plants)
– Angiosperms (flowering plants)
Kingdom Plantae - Gymnosperms
• Four phyla of gymnosperms
– Gnetophyta- weird group - no info!
– Ginkgophyta (Ginkgos)- single, very hardy species
– Cycadophyta (Cycads)- palm-like plants of tropical &
subtropical areas
– Coniferophyta (Conifers)- cone bearing plants, by
far dominant gymnosperm
Ginkgophyta (Ginkgos)-
Cycadophyta (Cycads)-
Kingdom Plantae - Gymnosperms
Confiferophyta
• Many common trees (pines, redwoods, sequoias)
• Heterosporous- produce 2 types of cones
– ovulate cone (female)
– megaspore mother cell (2N) produces megaspore (1N)
– megaspore divides to produce multicellular megagametophyte
– one cell specializes as an egg cell
– pollen cone (male)
– produces hundreds of pollen grains (microgametophytes)
female cone
Male cone
fertilization
pollination
Female g
ametophy
te
not free-l
iving
seed
Sporophyte
dominant
Kingdom Plantae - Phylum Anthophyta
• Characterized by development of a flower
• By far the most successful modern plant
• Angiosperms are composed of two classes
– monocots (grasses, orchids, palms)
– dicots (broadleaf plants)
• Remainder of botany section will focus on
angiosperms