History of Life Exam 3

First land plants

developed during the paleozoic era at the end of the cambrian period

Fossilized plant spores

earliest land plant fossil record, found in West Australia and dates to early Ordovician era (480 MYA)

Plants that live on land evolved from

green algae which lacks stems, roots, leaves, and vascular systems

The first macrofossil evidence of land plants

Cooksonia the primitive vascular plant from 425 MYA found in the Rhynie chert

Molecular clock for origin of land plants

During cambrian period (500 MYA)

Rhynie cherts (Scotland)

first fossil record of whole plants in lower Devonian (400 MYA) by Mackie, Deemed most influential work on fossil plant

Aglaophyton major

sporophyte generation of pre-vascular, land plant of lower Devonian (410 MYA) and remnant of what we think first non-vascular bryophyte land plants looked like

Charophytes

the freshwater green algae land plants evolved from which possessed pre-adaptations for land life

Fresh water green algae adaptations

land environmental conditions like rain exposure, temperature variation tolerance, high levels of UV, and seasonal dehydration

Factors that favored plants on land

less water and support but more light and CO2

Problems living out of water on land

Dessication, support, reproduction (on land), salt balance, gas and heat exchange, waste excretion

Plants and water loss

waxy cuticle on leaves, stomates, and guard help mitigate water loss

Tracheophyte

like a stem, its roots have vascular bundles of xylem and phloem, the system in roots continues with the shoot to enable efficient movement of water and nutrients in the plant body

Vascular tissue

the plant circulatory and support system

Xylem

pipeline of dead cells arranged end to end for water and mineral transport, cells that form xylem die and leave hollow tunnel which provides upward fluid passages

Phloem

Made of sieve elements that are arranged end to end to make passages and companion cells; carry materials up and down plant body with mature cells

Angiosperms

flowering plants, most vascular and the majority of plants

Primary growth

occurs in apical meristems at top of root and shoot and is a growth of vertical length

Secondary growth

growth of thickness in dicots and gymnosperms but not monocots that occur from lateral meristems

Vascular cambium

Between the primary xylem and phloem, on its inside it produces the secondary xylem and on the outside it makes the secondary phloem

Heartwood

made as older xylem clogs and ceases to function

Cork cambium

makes protective covering of shoots which is cork aka bark

Plant primary growth

roots and stem of plants, up and down

Plant secondary growth

midsection of plant, wider

Gametophyte generation

dominant life state of nonvascular plants, where spores undergo mitosis to become gametophytes that will fuse to make

Major innovations for plant reproduction out of water

volution of the seed along with vascular system and alternating generations

Seed structure

plant embryo and food reserve enclosed in a protective outer covering (coat)

Seed production

from ripened ovule after the embryo sac is fertilized by sperm from pollen making a zygote

Angiosperm appearance

Early cretaceous, but genetic evidence suggest earlier divergence (over 300 mya)

origin of plants

500 mya from type of green algae (charophytes)

Early vascular plants

450 MYA, root and leaves appear 390 MYA

first seed plants

385-400 MYA, forest were 380 MYA