Seedless Vascular Plants Overview

These flashcards cover vocabulary and key concepts related to seedless vascular plants, including their structures, life cycles, and evolutionary traits.

What are the different types of steles in vascular plants?

• Protostele:

  • The simplest and most primitive type.

  • Has a solid core of vascular tissue (xylem and phloem).

  • Common in early vascular plants like bryophytes.

• Siphonostele:

  • A more advanced type with a central pith surrounded by vascular tissue.

  • Allows for more complex arrangements and is found in ferns.

• Eustele:

  • Most complex type found in flowering plants (angiosperms).

  • Vascular bundles are arranged in a ring, allowing for efficient growth and development.

Which type of stele is more primitive?

• Protostele is the more primitive type.

Which type of stele is most recently derived?

• Eustele is the most recently derived type.

What are the different types of xylem tissue?

Tracheids:

• Tapering ends + pitted walls; no perforations

• Conduct water and provide structural support.

• Prim. vasc. trait, (ferns and gymnosperms)

  • Vessel elements:

• Tube-like structure of elongated cell; connects by perforations

• Continuous tubes (vessels) for better water transport.

• Found in angiosperms (flowering plants).

What plant groups are included in seedless vascular plants?

Seedless vascular plants include groups such as ferns, horsetails, and clubmosses.

Shared traits of seedless vascular plants

• P.S.

• Sporophyte dominant; free living

• Vasc. tissue

• Oogamous

• Dispersal via spores

What are the more primitive and more advanced traits in seedless vascular plants?

Primitive:

• Microphylls

• Vasc. tissue (xylem + phloem); only tracheids

• Sporophyte dominant

• H2O for fertilization

• Reproduce via spores

• Rhizomes instead of roots

• Homosporous

Advanced:

• Better Vasc. tissue → better H2O transport + support

• Sporophyte dominant

• Megaphylls

• True roots, stems + leaves

• Heterosporous

• Diverse habitats

How do ferns and bryophytes share an evolutionary history?

• Common ancestor

• Flagellated sperm → H2O for fertilization

• Reproduction via spores

• Alternation of generations

What traits do ferns and bryophytes share?

Both have a life cycle that includes alternation of generations.

• Both reproduce via spores

• Both require water for successful fertilization.

• Both exhibit some form of gametophyte generation in their life cycle.

• Cuticle and stomata to reduce H2O loss

• Rhizoids/true roots for anchoring

Distinct traits of bryophytes

Non-vascular plants that lack specialized tissues for water transport.

• Dominant gametophyte generation

• Typically small and grow close to the ground.

• Exhibit structures like rhizoids for anchoring instead of roots.

  • no true roots, leaves, stems

• More dependent on moisture

• Asexual reproduction

Distinct traits of ferns

Vascular plants with specialized tissues (xylem and phloem) for efficient water and nutrient transport.

• Dominant sporophyte

• Generally larger and can grow in a wider range of environments.

• Possess true roots, stems, and leaves (megaphylls).

• Some heterosporous

• Have fronds that uncurl as they grow (fiddleheads).

What is the evolutionary trend observed in the gametophyte from more primitive plant groups to more recently evolved plants?

Gametophyte is reduced over time → non dominant

Which type of xylem tissue is more primitive?

Tracheids are considered more primitive.

Which type of xylem tissue is a more efficient water conductor and why?

Vessel elements are more efficient conductors.

• Their wider diameter allows for greater water flow.

• Continuous vessels reduce resistance in water transport.

What are sieve elements?

Specialized cells in the phloem that transport nutrients, particularly sugars.

What are tracheids?

Tracheids are long and narrow cells in the xylem of plants.

• They help transport water and minerals.

• They support plants due to their strong cell walls.

• Found in most vascular plants like ferns and gymnosperms.

What are vessel elements?

Vessel elements are short, wide cells in the xylem of vascular plants.

• They work together to transport water and nutrients more efficiently than tracheids.

• Have perforations in their end walls that allow for easy flow of water.

• Mainly found in flowering plants (angiosperms).

Protostele, Siphonostele, and Eustele

Three types of Stelle that make vascular tissue:

• main tissue of stem + root of vasc. plants

• consists of Xylem, Phloem + Pith

What are sori/sorus?

Sori are clusters of sporangia on the underside of fern leaves.

• A sorus is a single cluster of sporangia.

• They produce and release spores for reproduction.

What is an indusium?

An indusium is a protective covering that surrounds sori in ferns.

• It helps shield the developing spores from damage and desiccation.

What is a false indusium?

A false indusium is a fold of the leaf itself that protects the sori.

• It looks like an indusium but is not a separate structure.

What is an annulus?

An annulus is a ring of specialized cells found on sporangia in ferns.

• It helps in the release of spores by splitting open when dry.

What is a strobilus?

A strobilus is a cone-like structure in plants that bears reproductive organs.

• It can contain spores (like in ferns) or seeds (like in conifers).

• Strobili help in the reproduction process by facilitating the dispersal of spores or seeds.

What are elaters?

- Elaters are specialized cells found in some sporangia of bryophytes (like mosses).

• They help in the dispersal of spores by twisting and untwisting in response to humidity changes.

• This movement aids in spreading the spores further away from the parent plant.