Seedless Vascular Plants Seedless Vascular Recall Bryophytes have

Seedless Vascular Plants

Seedless Vascular § Recall: Bryophytes have only one way to transport water------Osmosis § This fact limits their height § New plants evolved from these Bryophytes with a detailed transport system---Vascular tissue § Specialized cells that conduct water and nutrients throughout the plant

Evolution of Vascular Tissue § Tracheids: Hollow plant cell in xylem tissue with thick cell walls that resist pressure § Great evolutionary innovation of plant kingdom § Why?

Xylem and Phloem § 2 Types of Vascular Tissue § Xylem: a transport subsystem that carries water upward from the roots to every part of a plant § Phloem: a transport subsystem that transports solutions of nutrients and carbohydrates produced in photosynthesis

Xylem and Phloem § Both can move fluids through the plant against gravity § Due to the thick walls of xylem and lignin, a substance that makes cell walls rigid, plants were able to grow taller and more upright.

Xylem and Phloem

Ferns and Their Relatives § Seedless vascular plants include club mosses, horsetails, and ferns § Vascular plants have TRUE roots, leaves and stems § Roots: underground organs that absorb water and minerals § Leaves: photosynthetic organs that contain one or more bundles of vascular tissues § Stems: supporting structures that connect roots and leaves

Club Mosses § Most club mosses produced the first forests on Earth § These exist today in huge beds of coal § Today club mosses are small plants that live in moist woodlands

Horsetails § Plant that typically grows 1 meter tall § Scale-like leaves are nonphotosynthetic § Called horsetails because its stems look similar to horses tails and contain crystals of abrasive silica § Used in ancient times to scour pots and pans

Ferns § § § Evolved about 350 million years ago 11, 000 species of ferns are living today Ferns have vascular tissue, strong roots, creeping or underground stems called rhizomes, and large leaves called fronds § Ferns are most abundant in wet habitats and need little light to survive

Ferns

Life Cycle of Ferns § Ferns and other vascular plants have life cycles in which the diploid sporophyte is the dominant stage § Fern sporophytes develop haploid spores on the underside of their fronds in tiny containers called sporangia