Lecture 14: Vascular Plants

Tracheophytes

Vascular plants

• possess tracheids

• major plant organs: stems, roots, leaves

Can be non-seed producing or seed-producing

Represent ~90% of all plant life

Thracheid

Elongated overlapping tubes with pits. Assists with structural support

Lignin

Provides stiff, structural support. Allows turgor pressure (vacuole can have death, normal, or turgor shape to know water needed)

Vascular tissue

Xylem and phloem to transport water, nutrients, and food throughout organism

Xylem

Moves water and dissolved minerals from the roots to the rest of the plant

• moves in one direction

Phloem

Transports food produced by photosynthesis from the leaves to other parts of the plant

• Moves in two directions

Stems

• Produce leaves and sporangis

• Contain phloem and xylem (also contains tracheids and lignin)

Roots

Specialized for uptake of water and minerals from the soil

Leaves

Photosynthetic function

Waxy cuticle

Prevents desiccation

• adaptation to conserve water

Contains cutin

Cutin

Component of the cuticle; also helps block pathogens

Stomata

Pores that open and close to allow gas exchange while minimizing water loss

• “guard” cells

Microphyll

(aka lycophyll)

Simplest, most ancient leaves

• seen in lycophytes

• only a single, unbranched strand of vascular tissue

Euphyll

(aka megaphyll)

Leaves that have multiple veins, usually branching one or more time in leaf

• larger size is more advantageous

• evolved in a series of steps

Rhizome

Characteristically horizontal stem of a plant that is usually found undergound, often sending out roots and shoorts out from nodes

• present in lycophytes, pteridophytes, and angiosperms

Apical meristems

Regions of actively dividing plant cells that drive primary vertical growth