Plant Biology: Charophytes and Embryophytes

Charophytes and Plants

• Charophytes are protists that share similar adaptations with land plants.
• They have in common with plants: sporopollenin, cellulose in the cell wall, flagellated sperm, and phragmoplast.
• Sporopollenin provides protection from the elements and is important for the evolution of land plants.

Embryophytes

• Developing embryos are contained, giving them a better source of food and protection until they can move outside.

Plant Life Cycles

• Antheridia and Archegonia play a role in plant life cycles, with sperm swimming from antheridia to archegonia to fertilize the egg.
• Seeds allow offspring to survive for long periods in harsh conditions prior to germination.
• Vascular tissue allows plants to grow tall and transport water and nutrients between distant roots and shoots.

Bryophytes

• Bryophytes include mosses (phylum bryophyta), liverworts (phylum hepatophyta), and hornworts (phylum anthocerotophyta).
• The life cycle of Bryophytes involves:
  • Gametophyte stage: produce haploid gametes
  • Sporophyte stage: produce haploid spores
• In mosses, the sporophyte has a seta and capsule, while in liverworts, the sporophyte lacks a seta.
• In hornworts, the sporophyte also lacks a seta.

Seedless Vascular Plants

• Seedless Vascular plants differ from Bryophytes in that they grow much taller due to vascular tissue, and are sporophyte-dominant.
• Vascular tissue is an important adaptation for transportation of water, minerals, and sugars.
• Xylem transports water up from roots to leaves, while phloem transports sugar back down to roots.
• Sporophylls are leaves with sporangia, differing from macrophylls or microphylls.
• Homosporous plants have one type of spore, while heterosporous plants have different types of spores in the sporophyte.

Vascular Seedless Plants

• Phylum lycopodia includes club mosses (homo), quillworts (hetero), and spike mosses (hetero).
• Phylum monilophyta includes horsetails (equisetum), fern, psilotum (homosporous), and whisk ferns (homosporous).
• Whisk ferns are considered living fossils because they have remained unchanged for a long time.

Comparison of Plant Groups

• Bryophyte life cycle differs from Seedless Vascular, Gymnosperm, and Angiosperm life cycles.
• Water is required for sperm to swim and fertilize the egg in plant life cycles.