Kingdom Plantae Nonvascular and Seedless Vascular Plants Plants

Kingdom Plantae • Nonvascular and Seedless Vascular Plants

Plants: General Features • Sporic meiosis • General Life Cycle. Fig. 37. 3

Plants: Where from? • Green algae: One line of green algae gave rise to all plants Fig. 32. 12

Plants: Where from? • Green algae. One line of green algae gave rise to all plants • Plantae is monophyletic kingdom. Fig. 37. 2

Kingdom Plantae • Today we focus on phyla grouped into: • Nonvascular plants – Plants, but lack true (lignified) vascular tissue • Seedless vascular plants – Plants that have true vascular tissue (phloem and xylem), but reproduce only by spores (no seeds made) • Note that all the plants discussed today make swimming sperm (they must swim through a film of water to reach an egg). Sexual reproduction requires moist conditions!

Kingdom Plantae • Nonvascular plants – Phylum Bryophyta (mosses) – Phylum Hepaticophyta (liverworts) – Phylum Anthocerophyta (hornworts) Moss Hornwort Liverwort

Nonvascular plants: general features • Lack true (lignified) vascular tissues – Leaf: flat structure containing vascular tissue – So, mosses lack true leaves. Make “leaf” – Stems: requires vascular tissue too – So, mosses lack stems. Make “stem”.

Nonvascular plants: general features • Gametophyte dominant (photosynthetic) – Most of life spent here! – Sporophyte partially dependent on gametophyte during development.

Phylum Bryophyta (mosses) • Largest group of nonvascular plants (10, 000 species) • Gametophytes have “leaves” and “stems” (lack vascular tissue) • Make multicellular rhizoids that anchor plant to ground (these NOT roots: lack vascular tissue, don’t absorb much water).

Phylum Bryophyta (mosses) • Life cycle: the movie! • Starring: – Breye O’Fyte as the gametophyte – Spoh Rangium as the capsule

Gametophyte/sporophyte relations • So, vertical stalked structures on gametophytes are the second generation in life cycle (sporophytes) • Note sporophytes grow on and are at least partly dependent upon gametophyte • “Deadbeat sporophytes”, unable to live independent lives. Fig. 37. 4

Moss importance • Can be important producers in some habitats • Economic importance: peat moss!.

Peat moss • Dried or partially decomposed gametophytes of Sphagnum gametophytes

Peat moss • Sphagnum grows in wet areas called bogs (very acid soil, water-logged, little decomposition). Aerial (left) and ground (above) views of bogs

Peat moss • Dead Sphagnum builds up as peat • Abundant: about 1 billion acres of peat bogs in world (northern hemisphere mostly) • 1% of Earth’s land surface!.

Peat moss • Peat moss used as soil amendment or potting mix (good waterholding capability) • Harvesting peat is important industry in northern temperate zone (Canada, Denmark, Sweden, etc. ) • Industry worth many millions of dollars a year.

Harvesting peat moss Step 1: Bogs are wet: must ditch them to drain them Step 2: drying top layer Step 3: Vacuum up the dried moss

Peat bogs as archeological sites • Bodies buried in bogs are often wellpreserved (“Bog people”). • Allow archeologists to study vanished societies. A Book about Bog People Tollund man (Denmark): Dated to around 0 AD Grabaulle man (Denmark): Dated to around 300 AD Wooden wheel from a bog dated 2700 BC

Phylum Hepaticophyta (liverworts) • Fairly large (6, 000 species) • Two groups: – 1) Leafy liverworts (look like mosses, but have unicellular rhizoids). Most of these tropical, many are epiphytes (grow on other plants). Leafy liverworts on tropical tree leaf Leafy liverwort

Phylum Hepaticophyta (liverworts) • Two groups: – 2) Thallose liverworts. Simple flattened bodies. Occur locally (emphasized in lab). Thallose liverworts

Phylum Hepaticophyta (liverworts) • Thallose liverwort life cycle: similar to moss, in that gametophyte is major phase • Sporophyte smaller and dependent on gametophyte.

Phylum Hepaticophyta (liverworts) • But two small differences from moss: – antheridia on stalked structure called antheridiophore – archegonia on stalked structure called archegoniophore.

Phylum Hepaticophyta (liverworts) • Note that asexual production can also occur via gemmae (made in gemma cups) • When splashed out by rain drop, can grow by mitosis to new gametophyte. Close-up of gemmae in cup Low power view

Phylum Anthocerophyta (hornworts) • Small group (100 species) • Gametophytes look like thallose liverworts, but sporophytes larger, photosynthetic, and less dependent on gametophyte • Green vertical structures below are sporophytes growing out of gametophytes.

Kingdom Plantae • Seedless vascular plants – Phylum Psilophyta (whisk ferns) – Phylum Lycophyta (club mosses) – Phylum Sphenophyta (horsetails) – Phylum Pterophyta (ferns) – Several other phyla that are now extinct (but had glorious fossil past)

Seedless Vascular Plants (SVPs) • General features: • Sporophyte is dominant generation and can grow independent of gametophyte (no more “deadbeat sporophytes”!) • Gametophytes small, reduced • As with nonvascular plants, SVP gametophytes can grow independent of sporophyte.

Seedless Vascular Plants (SVPs) • • General features: Have cuticle, stomata Have vascular tissue (phloem and xylem) Thus, can make true leaves, stems, and roots.

Seedless Vascular Plants (SVPs) • 2 kinds of leaves – 1) microphyll: an epidermal outgrowth supplied by a vein of vascular tissue – 2) megaphyll: a reduced branch system that has become flattened with photosynthetic tissue between branches. Evolution of microphyll (simple leaf) Evolution of megaphyll (complex leaf)

Kingdom Plantae • Seedless vascular plants – Phylum Psilophyta (whisk ferns) – Phylum Lycophyta (club mosses) – Phylum Sphenophyta (horsetails) – Phylum Pterophyta (ferns) – Several other phyla that are now extinct (but had glorious fossil past)

Phylum Psilophyta (whisk ferns) • Small group (about 6 species) • In lab, will see Psilotum • Simple sporophyte bodies: just stems. No leaves or roots • Stems with dichotomous branching (evenly split into two smaller stems). Psilotum branches dichotomously (lumps are sporangia) Psilotum growing in crack of rock

Phylum Psilophyta (whisk ferns) • Sporangia on aerial stems • Underground stems called rhizomes: have filamentous rhizoids. Closed (top) and split (bottom) sporangia on stem

Phylum Lycophyta (club mosses) • Second largest SVP group (1, 100 species) • Sporophytes with true leaves (microphylls), roots, stems. Isoetes Lycopodium Selaginella

Phylum Lycophyta (club mosses) • Sporangia produced on leaves called sporophylls • Sometimes sporophylls clustered into a group called strobilus.

Phylum Lycophyta (club mosses) • Interesting genera: – Lycopodium – Some native to pitcher plant bogs in Southeast U. S. Pitcher plant bog Lycopodium in bog

Phylum Lycophyta (club mosses) • Interesting genera: – Selaginella – One desert species called resurrection plant – Rolls into ball as it dries, when moistened unfurls and can grow again. Resurrection plant, Selaginella lepidophylla

Phylum Lycophyta (club mosses) • Interesting genera: – Isoetes – Small genus. Some southeastern species are endangered – Grow in pools of water on granite outcrops (like Stone Mtn GA).

Phylum Lycophyta (club mosses) • Interesting genera: – Granite outcrops as scattered habitat “islands” – Two Isoetes species found only in granite outcrop pools, vulnerable to human disturbance. Isoetes melanospora, an endangered species

Phylum Sphenophyta (horsetails and scouring rushes) • Small group: 1 genus (Equisetum) with 15 species • Make true stem (hollow), roots, leaves (small, may be reduced megaphylls) on sporophyte.

Phylum Sphenophyta (horsetails and scouring rushes) • Gametophytes small (several mm long), green, independent of sporophyte.

Phylum Sphenophyta (horsetails and scouring rushes) • Horsetails with whorls of side branches • Scouring rushes lack side branches. Scouring rush Horsetail

Phylum Sphenophyta • Sporangia on underside of stalked structures called sporangiophores • Clustered in strobilus at stem tip.

Phylum Pterophyta (ferns) • Largest SVP group (11, 000 species) • Mainly tropical, but many in temperate zone • Make true leaves (megaphylls), stems, roots on sporophyte • Gametophytes small, delicate, independent of sporophyte. Fern gametophytes

Phylum Pterophyta (ferns) • Sporangia often on underside of leaves • If in patch, patch called sorus (plural: sori) • Some patches covered with tissue (indusium). These sori are uncovered (naked) Each sorus here covered by indusium

Phylum Pterophyta (ferns) • Closeup of sorus with indusium (rounded structures are sporangia).

Phylum Pterophyta (ferns) • Life Cycle Movie:

Phylum Pterophyta (ferns) • Fern Importance: – Ornamental plants (indoor and outdoor). Birdnest fern Maidenhair fern Frilly boston fern Lady fern

Phylum Pterophyta (ferns) • Fern Importance: – Primary producers (important part of biomass of some habitats). Fern forest in Tasmania, Australia

Phylum Pterophyta (ferns) • Fern Importance: – Some are invasive exotics (non-natives that become weeds): example, Japanese climbing fern in SE U. S. – Like kudzu, climbs on and shades other plants.

Kingdom Plantae • Seedless vascular plants – Phylum Psilophyta (whisk ferns) – Phylum Lycophyta (club mosses) – Phylum Sphenophyta (horsetails) – Phylum Pterophyta (ferns) – Several other phyla that are now extinct (but had glorious fossil past)

Extinct SVPs and Their Importance Today • Dominated land during Carboniferous Period (354 -290 million years ago) – Coal swamps full of extinct plants – Reconstructions below based on fossils from coal.

Fossil Seedless Vascular Plants (SVPs) • Coal is incompletely decomposed carbon from ancient plants (burns!).

Fossil SVPs • Coal: – Vital source of energy today!. Coal seam in western U. S. desert

• Coal: Fossil SVPs – Vital source of energy today! (“Fossil fuel”) – >50% of U. S. electricity. Mining coal for power

Fossil SVPs • Most important economically of all Nonvascular Plants and SVPs – Vital source of energy today!

Setting the stage for pollen/seeds • Land plants have specialized gametes (egg, sperm). Sperm must swim in water to reach egg. • Land plants have specialized gametangia (antheridia and archegonia).

Setting the stage for pollen/seeds • Most of plants discussed so far do not have specialized gametophytes • They are homosporous plants: make one kind of meiospore.

Setting the stage for pollen/seeds • Heterosporous plants: make 2 types of meiospores. – One becomes male gametophyte and makes sperm – One becomes female gametophyte and makes eggs • Thus, make specialized spores and specialized gametophytes.