Plant Evolution and Diversity Reading: Chap. 30 A. Plants: fundamentals I. What is a plant? What does it do? A. Basic structure and function B. Why are plants important? - Photosynthesize C. What are plants, evolutionarily? -CO2 uptake D. Problems of living on land -O2 release II. Overview of major plant taxa - Water loss A. Bryophytes (seedless, nonvascular) - Water and nutrient uptake B. Pterophytes (seedless, vascular) C. Gymnosperms (seeds, vascular) -Grow D. Angiosperms (seeds, vascular, and flowers+fruits) Where? Which directions? II. Major evolutionary trends - Reproduce A. Vascular tissue, leaves, & roots B. Fertilization without water: pollen C. Dispersal: from spores to bare seeds to seeds in fruits D. Life cycles Æ reduction of gametophyte, dominance of sporophyte Fig. 1.10, Raven et al.
B. Importance of plants C. Where do plants fit, evolutionarily? 1. Food – agriculture, ecosystems 2. Habitat 3. Fuel and fiber 4. Medicines 5. Ecosystem services How are protists related to higher plants? Algae are eukaryotic photosynthetic organisms that are not plants.
Relationship to the protists What are the defining traits of plants? - Multicellular, eukaryotic, photosynthetic autotrophs - Cell chemistry: - Chlorophyll a and b - Cell walls of cellulose (plus other polymers) - Starch as a storage polymer - Most similar to some Chlorophyta: Charophyceans
Fig. 29.8 Points 1. Photosynthetic protists are spread throughout many groups. 2. Plants are most closely related to the green algae, in particular, to the Charophyceans. Coleochaete 3. Plantae has expanded to include green algae, red algae and glaucophyte Chara algae. What is in common?
1 “Land” plants only All “Land” plants (some but not all green algae) - Apical meristem - Alternation of generations (sporic life cycle)
C&R 29.3 C&R 29.6
“Land” plants only “Land” plants only - Multicellular, dependent embryos Æ “Embryophytes” - Multicelluar gametangia: antheridia and archegonia Moss life cycle
30.20
30.13 29.17a 30.14
The Phylogeny of Green Plants
a a D. Problems of land life: ri e te a c h Eukarya a rc B A
Green plants Adaptations for living in air
Land plants
Vascular plants
Seed plants
e a Gymnosperms Angiosperms e c y a ) h t l. p ) e ta y s a ) e o s a y h a ) ta a ta a r t ) s ta a ) t e e ) h p ) ) t s t t fe e a s ) a y e s e t c ts ) o s a s y y ) y y y i t te a l. t rm ) c e a e y r p ts r t ta t e h rn h ls h h h n s y y t a y e h e t a h o o r e r y ) y t e p i p p ) p ) o d h h y t h p a y y h h c o o s y p f o a o s o e p p o lg h h c c p w ti c w h e h h o k t o ) d o o c o p p h s d a p p o o a e a rw o n p s p p t s n e d s d a g g r o to p s o io o o e le r n e h r o s o o lo i e rs ri n a c k k e w t e o e th g o d v lv l a o p v t o y o c c i h h o r c y n in h d e n n n h e l o o h t e li n h r y y s p te e y c i g t e n i i n n R (r U (u C (c C (s H ( A ( B (m L (l P (w S (h P (f C ( G ( O (r G (g P (p A (a
Flowers
Seeds
Vascular tissue
Ability to live on land Green algae
Nonvascular plants Chloroplasts containing chlorophyll a + b and β-carotene Seedless vascular plants
2 1. Desiccation of plant 2. Resource acquisition - water and minerals
Fig. 30.10
REE, Fig. 1.10 - Roots - Water conservation - epidermis w/cuticle, REE, Fig. 1.10 stomata, guard cells
4. No water for reproduction 3. Light acquisition a. gamete dispersal and desiccation b. spore dispersal and desiccation C&R Fig. 29.7 a. Surface area - Leaves b. Fight gravity - Support c. Fluid transport - Vascular tissue, xylem and phloem
Fig. 1.10 - Fertilization and dispersal that are independent of water (some).
II. Overview of Taxa 1. Bryophytes
Liverworts (Hepaticophyta) Hornworts Mosses (Bryophyta) ~6500 species, moist (Anthocerophyta) ~12,000 species, environments ~100 species widespread
3 Bryophyte ecology: Bryophyte ecology: b. Global carbon cycle a. Groundcover and epiphytes
Groundcover Epiphytes
B. Seedless vascular plants (Pteridophytes) What’s new? 1. Vascular tissue, true leaves, true roots 2. Sporophyte dominant
Lycophyta Psilotophyta Sphenophyta Pterophyta - “club mosses” 30.17b
Other SVP developments: true leaves Other SVP developments: true roots
Moss phyllids
http://www.palaeos.com/Plants/Bryophyta/Bryophyta.html
Angiosperm, Fig. 29.10
Club moss, REE Fig. 19-3
4 1. Gymnosperms: Who are they? Figure 30-9 C. Seed plants - Gymnosperms
a a ri e te a c h Eukarya a rc B A
Green plants
Land plants
Vascular plants
Seed plants
e a Gymnosperms Angiosperms e c y a ) h a t l. p ) e t y rs a ) a e o s a y h a ) ta a ta a t ) s t a ) t e e ) h p ) ) t s y t y t fe e a s ) ta y ) e s e t c ts ) o s a a s y ) y y i t te a l. rm c e a e y r p ts r t t t e h rn h ls h h h n s y y t a y e h e y t a h o o r e r y ) y t e p i p p ) p ) o d h h y t h p a y h h c o c o s h y p f o a o s c o h e p p o lg h h c c p w ti w h e h to k n t o ) d o o o p p o s d a p p o o ra e a rw o n p s p p s e id s d a g g r o to p s io o o e le n e h r o s o o lo i e rs r n a c k k e w t e o e th g o d v v l a o p v t o y o c c i h h o r c n in h d e n n n h e l l o o h t e li n h r y y s p te e y y i t e n i i n n R (r U (u C (c C (s H ( A ( B (m L (l P (w S (h P (f C (c G (g O (r G (g P (p A (a Phyla: Flowers Ginkgophyta - 1 genus, 1 species: Ginkgo
Seeds biloba Cycadophyta - ~100 species Vascular tissue Conifers - 550 species: Pinophyta & “other” Ability to live on land Green algae (redwoods, cypresses, junipers, etc.)
Nonvascular plants Chloroplasts containing chlorophyll a + b and β-carotene Gnetophyta - 3 genera, 70 spp. Seedless vascular plants
Conifers Conifers
Biggest Giant sequoia
Tallest? oldest Coast redwood Bristlecone pine – 4795 in 2007
Conifers Conifers
Furthest north
White spruce highest
5 Conifers Conifers Widespread (boreal forest, temperate rain forest) Very important timber species
Most photographed
Monterey cypress http://www.pc.gc.ca/canada/nature/archives/2003/fe/ ART_IMAGES/map_boreal.gif
Conifers Conifers
Wet conditions Black spruce Dry conditions Juniper
D. Seed plants: Angiosperms 3. What’s new? (Phylum Anthophyta) ~270,000 species
Land plants a. Secondary growth Vascular plants Seed plants b. Continued g’phyte reduction Gymnosperms
l. a c. Pollen and heterospory s t s e s s e s m s t ts s s e te l. r e e e r t t t rn ls s y a e a t a o r r y e i d h t p g y h o o s h f ta s o e s l h c w w w e p k e d o o p o a p o e r n s o s s s a g w to s i d. Seeds d o le n e r s c i r rn c k d e e g e lv o to iv o o y h o e y in e n in n R U C S L H M L W H F C G R G P A Fruit Heterospory Flowers
Seeds Fruit Pollen Heterospory
Sporophyte-dominated life cycle
Alternation of generations Retention of embryo on parent Green algae Complex gametangia Thick-walled spores Nonvascular plants Retention of egg on parent Seedless vascular plants Simple gametangia Figure 30-26
6 1. Who are they? 2. Why are they important? Monocots: ~ 60,000 spp. a. Most diverse phylum, huge radiation Lilies, orchids, b. Base of many terrestrial food webs grasses, palms c. Basis of agriculture Dicots: Fruits Most of the rest Vegetables Trees, shrubs, forbs Grains Eudicots and ‘other’ d. Secondary compounds – drugs, medicines
A. What is “vascular tissue” III. Major Evolutionary Trends and what does it do? 1. Xylem A. Structure: Vascular tissue, leaves, & roots - water and nutrients up from B. Reproduction: Fertilization without water: pollen roots to stem, leaves: one way - hollow C. Reproduction: Dispersal of progeny: from spores to bare seeds to seeds in fruits - dead at maturity - secondary cell walls, lignin D. Life cycles Æ reduction of gametophyte, dominance of sporophyte 2. Phloem - photosynthate from leaves to roots, shoots, meristems - living at maturity - no secondary cell walls
3. Evolutionary Sequence Observed in Water- Conducting Cells
Simple water- First vascular tissue Tracheids Vessel elements conducting cells
Ends have gaps in secondary cell wall (inside) Ends have gaps through primary and secondary cell walls
Primary wall Primary wall Primary wall Primary wall (with cellulose) (with cellulose) (with cellulose) (with cellulose)
Lignin Secondary wall Secondary wall (with lignin) (with lignin)
Little structural Some structural Increased structural Found in gnetophytes support. Found in support. Found support. Found in and angiosperms fossils and present- in fossils all vascular plants day mosses
7 B. Fertilization without water 4. Secondary growth 1.pollen and heterospory
a. In Gymnosperms b. (lateral meristem - draw)
Conifer life cycle 29.14d
Co-evolution with animals 2. Flowers - more efficient fertilization (pollination)
Stamen = microsporangia Ovule = megasporangium plus integuments Carpel = stigma + style + ovary Petals and sepals = modified leaves, attract pollinators
C&R, 30.13
Many crops depend on natural pollinators
Darwin’s Hawk Moth
http://www.pbs.org/wnet/nature/bestofnature/video.html
US Postal Service http://www.berkeley.edu/news/media/releases/2006/10/25_pollinator.shtml http://encarta.msn.com/media_461530192_761578331_-1_1/Darwin's_Hawk_Moth.html
8 C. New mode of dispersing progeny 1. Seeds Seed formation
Incorrect color in “c” - should be C&R, Fig. 30.2 blue for food supply, which is haploid (megagametophyte). Conifer life cycle 29.14d
2. Fruits - more efficient dispersal Fruits - different kinds Wind-dispersed
Animal dispersed - eaten Pine seed Animal dispersed - riding Coevolution with animals Water-dispersed C&R, 30.15 30.20, 30.25
3. Angiosperm life cycle 2. Bryophyte life cycle and structure a. ovule inside carpel b. smaller g’phyte 1. G’phyte vs. s’phyte c. Double fert: 2. Archegonia and endosperm - 3n antheridia d. After fert: 3. Water for fert. Ovule Æ seed 4. Embryo on g’phyte Ovary wall Æ fruit 5. Spores for dispersal 6. Roots and leaves?
Fig. 30.17a
9