Lectures 15 & 16 - Seedless Vascular Plants

What three plants dominated earth’s vegetation long before angiosperms and conifers did?

Lycophytes, ferns, horsetails

What does fertilization require?

Water

What were the two groups of tracheophytes discussed?

Lycophytes and Polyopsida

What is the division of seedless vascular plants called?

Tracheophytes

What were the three families under the lycophyte umbrella?

Lycopodiaceae (club mosses), Selaginellaceae (spike mosses), Isotaceae (quillworts)

What were the five orders under the polyopsida class?

Psilotales (whisk ferns), Ophioglossales (adder’s-tongues), Equisetales (horsetails), Polypodiales/Marattiales (ferns)

What are the four features of land plants discussed?

Epidermis covered in waxy cuticle, multicellular gametangia/sporangia protected by layers of sterile cells, zygotes develop into multicellular embryos, upright body that grows into/toward brighter light

What lead to the evolution of more complex tissues and organs such as meristems and roots?

Vascular tissue (especially phloem)

What are the four features of vascular plants discussed?

Sporophytes dominant, independent, long-lived, larger than gametophytes; Sporophytes branched with multiple sporangia; Roots as an organ for absorption and conduction; Lignified secondary walls

Which generation is the dominant generation in vascular plants

Sporophyte generation

What are the two vascular tissues that are important to vascular plants?

Xylem and phloem

What are the three characteristics of lycophytes discussed?

Sporophytes have microphylls, Have true roots and stems, microphylls evolved from simple enations

What were the enations in lycophytes originally?

Small simple flaps of photosynthetic tissue

How did evolution change enations in lycophytes over time?

Evolution led to larger enations and vascularized microphylls

Describe extinct lycophytes. (2)

Tall trees, harbored lots of fossil fuels (coal)

State two examples of plants found in the Lycopodium genus.

Club mosses, ground pines

What are five characteristics of Lycopodium discussed?

Often grow on forest floors, stems simple or branched, develop from branching rhizomes, roots grow along rhizomes, leaves usually at least 1cm long

Plants in the Lycopodium genus are ______, meaning they produce one type of spore.

Homosporous

How are sporangia groups together for protection in Lycopodium?

In cones or strobili

Where does the sporangia develop in Lycopodium?

In axils of sporophylls

What are two ways in which spores can be used?

Original camera flash powder, fireworks

Selaginella and Isoetes are _______, meaning they produce two types of spores produced from one of two types of sporangia.

Heterosporous

What structure do Selaginella and Isoetes have?

Ligule

What is so special about some Selaginella?

They have the abilty to survive extreme drying; They can tolerate complete desiccation and recover quickly when water becomes available.

Desiccation-tolerant plants such as Selaginella have more copies of what kind of genes?

Stress-related genes

What are the four characteristics of Isoetes specifically?

Secondary growth in an underground corm, mega- and microsporangia at the base of sporophylls, looks like grass, no strobili

What is unique about Psilotum?

They lost the capacity to make roots and leaves

How many extant species are under the genus Equisetum?

15

What are the two characteristics of Equisetophytes discussed?

Aerial stems with a whorl of fused leaves at the node, stems have a hollow pith

What is the extinct horsetail genus discussed?

Calamites

What are three uses of horsetails?

Crafting, tea, landscaping

Are asparaguses classified as horsetails? Why

No - horsetails belog to an ancient lineage, reproduce by spores, and have no flowers. Asparaguses belong to angiospores and produce flowers, fruits, and seeds.

How many species of ferns are there?

Around 12,000

Which generation is dominant in ferns?

Sporophyte generation

Describe the leaf development of ferns.

Fronds first appear as a fiddlehead, then unroll and expand

What two fern characteristics can be used to tell them apart?

Frond shape and sori

Which frond shape is rare and not divided?

Simple

Which frond shape is divided into two leaves once?

Pinnate

Which frond shape is very finely divided and feathery?

Bipinnate/Tripinnate

Describe the sori of ferns.

Round, kidney-shaped, or elongated

What reveals the true evolutionary relationships of ferns?

DNA

What are the five ways ferns can be used as discussed in class?

Art, decor, design, medicine, food

What kind of ferns are edible?

Ostrich fern

Why are fern fiddleheads boiled or steamed?

To remove bitterness and toxins

Why are ferns used in art?

For their unique shapes and textures