1. ADAPTATIONS OF PLANTS I. Establishment of Plants on Land
Plants evolved from multi-cellular aquatic green algae.
Before plants could thrive on land, they had to be able to do three things:
1. absorb nutrients from their surroundings
2. prevent their bodies from drying out
3. reproduce without water to transmit
sperm

2. A. Absorbing Nutrients
aquatic algae and plants take nutrients from the water around them
on land, most plants take nutrients from the soil with their roots
the first plants had no roots, fossils show that fungi lived on or within the underground parts of many early plants helping early land plants get nutrients from the Earth’s rocky surface
this symbiotic relationship (between fungi and the roots of plants) is called mycorrhizae

3. B. Preventing Water Loss
the first plants lived at the edges of bodies of water, where drying out was not a problem
the cuticle, a waxy watertight covering, which reduces water loss, made it possible for plants to live in drier habitats
stomata – pores that permit plants to exchange oxygen and carbon dioxide and also release water into the air (transpiration)
guard cells – are specialized cells that surround each stoma

4. Stomata and Guard Cells

5. C. Reproducing on Land
aquatic algae reproduce sexually when sperm swim through the water and fertilize eggs
in most plants, sperm are enclosed in a structure that keeps them from drying out ex: pollen
pollen permits the sperm of most plants to be carried by wind or animals rather than by water

6. Vascular Tissue, Seeds, and Flowers
there was no basic difference in structure between the aboveground and underground parts of the earliest plants
some of the important changes in plant development include roots, stems, leaves, and conducting tissue

7. A. Advantages of Conducting Tissue
the first plants were small and materials were transported by osmosis and diffusion
the existence of vascular tissue allows for larger and more complex plants
vascular plants – plants with a vascular system
nonvascular plants – plants without a vascular system

8. B. Advantages of Seeds Seeds offer a plant’s
offspring several survival advantages:
1. protection - the seed coat of a seed protects the embryo
2. nourishment - stores food for the embryo as it starts to grow.
3. plant dispersal - many have structures that help in seed dispersal.
4. delayed growth - seeds make it possible for a plant embryo to survive through unfavorable periods and germinate later when conditions are favorable

9. C. Advantages of Flowers
flowers make plant reproduction more efficient because they attract animals, such as insects and birds, which carry pollen from one flower to another
flowering plants that are pollinated by animals produce less pollen and cross-pollination can occur between individuals that live far apart

10. Plant vascular structure Plants
Shoot
Plants
Root

11. xylem – transports water and nutrients
The following features characterize most
vascular plants:
xylem – transports water and nutrients
phloem – transports organic nutrients (food)
shoot – the part of the plant that grows upward
root – the part of the plant that grows downward
meristem – zones of actively dividing plant cells; produces plant growth

12. Xylem & Phloem