complex reproductive structures such as flowers or cones
• Evolutionary tree of some major plant groups
Bryophytes苔蘚類(non-vasvular plants)
Tracheophytes維管植物 (vascular plants)
• Well-protected and well-provisioned embryos
– Seeds
• wind
– Fruit
• Animal forager and dispersed the indigestible seeds
• Waterless dispersal of sex cells
• The ancestors of plants lived in ቤተ መጻሕፍቲ ባይዱresh water
– Highly variable
• Temperature • Chemicals in water • Periods of dryness
Key Features of Plants
• Multicellular • Photosynthetic • Plants are adapted to life on land • Alternating generations of diploid
• Lignin – increases rigidity, thereby increasing sun exposure; vascular plants
Plant Embryos Are Protected and Plant Sex Cells May Disperse Without Water
seed plants
Liverworts
Mosses
Ferns
Gymnosperms
Angiosperms
無種子維管束植物: 無管莖維 束 和管(葉為束等輸植構導物造組:織僅)蘚，苔沒植有物真不正具的維根、維植蕨媒管物類孢束不，子植產它來維束物生們散管，中種會播束因維和，子產。植此管葉有，生物具束等些如風:有植器蕨真物官種子類正體，子繁、的內使植殖乾抵裸根的植物燥抗子、維物:的乾和裸莖管體種燥被子和束內子，子植葉組的不而植物等織水但且物和構貫分可在都被造穿和以適具子。根養長宜有植、分期環維物莖的保境管靠存下種，萌
• Green algae, closest living relatives
– DNA comparisons – same type of chlorophyll and accessory
pigments for photosynthesis – Food storage
• starch
– Cellulose cell walls
and haploid stage (reference)
spores n
nnn
MEIOSIS
spore mother cell 2n
haploid diploid
gametophyte (n)
Haploid
egg n
n sperm
FERTILIZATION
Diploid
2n zygote
sporophyte (2n)
by water currents or propelled by flagella
Plant Bodies Resist Gravity and Drying
• Roots/root-like structures – anchor and get water and nutrients; all land plants
reproduce – Straddles the boundary between aquatic
and terrestrial life
• Waxy cuticle – limits water loss; all land plants
• Stomata: gas exchange and limit water loss; all land plants
• Conducting vessels – transport water and mineral in the plant; vascular plants
The huge, foul-smelling flower of the stinking corpse lily Parasite
What Is the Evolutionary Origin of Plants?
• Photosynthetic protists
– Probably similar to today’s algae – Lacked true roots, stems, leaves, and
2n embryo
Environmental challenges of plants living on land
• No supportive buoyancy of water • Not bathed in a nutrient solution • Air is a drying medium • Gametes and zygotes cannot be carried
– Pollens
• wind
– Flowers
• Animal pollinators
What Are the Major Groups of Plants?
Two major groups of land plants
• Nonvascular plants (moss…)
– Lack Conducting Structures – Requires a moist environment ot
輸送加快，並且芽可時支，持種植子物內體儲，藏使的其養直分立可。以供 因此，維管束植給物其長內得的比胚蘚發苔育植，物增高加大種。子植物
繁殖和擴張生長範圍的能力。 因此，種子植物在現今地球陸地 上占了大部分的生長面積
Ancestral green alga
Green algae gave rise to plants