Biology II Chapter 27

Club mosses (Phylum Lycopodiophyta)

A phylum of seedless vascular plants with a life cycle similar to that of ferns

Mosses (Phylum Bryophyta)

A phylum of spore-producing nonvascular plants with an alternation of generations in which the dominant n gametophyte ~10000 spp.

Stomata

Small pores located in the epidermis of plants that provide for gas exchange for photosynthesis

Megaspores

The n spore in heterosporous plants that gives rise to a female gametophyte

Megaphylls

Type of leaf found in horsetails, ferns, gymnosperms, and angiosperms; contains multiple vascular strands

What adaptations do ferns have that both algae and bryophytes lack?

Unlike algae and bryophytes, ferns have dominant sporophytes that possess vascular tissue, as well as stems, leaves (megaphylls), and roots.

In plant life cycles

the first stage in the diploid sporophyte generation is the zygote

Four Major Plant Groups

- Bryophytes - Seedless vascular plants - Seeded vascular plants: Gymnosperms and Angiosperms

Oldest known megafossils of early vascular plants were found...

420 Ma

___ is a leaf that arose from a branch system.

A megaphyll

Liverworts (Phylum Hepatophyta)

A phylum of spore-producing, nonvascular, thallose or leafy plants with a life cycle similar to that of mosses - sexual and asexual reproduction ~6000 spp.

Hornworts (Phylum Anthocerophyta)

A phylum of spore-producing, nonvascular, thallose plants with a life cycle similar to that of mosses ~100 spp.

Polyploids

A polyploid whose chromosomes are derived from a single species - Ferns are interesting research plants for studies in genetics because they are polyploids

Spore

A reproductive cell that gives rise to individual offspring - The mature sporophyte has special cells that divide by meiosis to form haploid spores

Sporangium

A spore case; each spore can give rise to a new gametophyte thallus

Sori

In ferns, a cluster of spore-producing sporangia

Protonema

In mosses, a filament of n cells that grows from a spore and develops into leafy moss gametophytes

Archegonia

In plants, the multicellular female gametangium (sex organ) that contains an egg

Heterospory

Production of two types of n spores, microspores (male) and megaspores (female) - certain ferns and club mosses (known as spike mosses) exhibit heterospory

Zygote

The 2n cell that results from the union of n gametes in sexual reproduction. Species that are not polyploid have haploid gametes and diploid zygotes

Prothallus

The free-living, n gametophyte in ferns and other seedless vascular plants

Which of the following are parts of the gametophyte generation in mosses: antheridia, zygote, embryo, capsule, archegonia, sperm cells, egg cell, spores, and protonema?

The haploid gametophyte generation in mosses includes the following: spores, protonema (each develops from a spore), archegonia (produce egg cells by mitosis), and antheridia (produce sperm by mitosis)

Plants probably descended from a group of green algae called

charophytes

Cuticle

covering over the epidermis of the aerial parts of plants that reduces water loss; composed mainly of cutin, a waxy substance

A strengthening compound found in cell walls of vascular plants is

lignin

Antheridia

the multicellular male gametangium (sex organ) that produces sperm cells

These plants have vascularized stems but lack true roots and leaves.

whisk ferns

Alternation of Generations

A type of life cycle characteristic of plants and a few algae and fungi in which they spend part of their life in a multicellular n gametophyte stage and part in a multicellular 2n sporophyte stage

Plant Reproduction

All plants produce spores by meiosis, in contrast with algae and fungi, which may produce spores by meiosis or mitosis - Fetilization of egg by sperm cell -> zygote -> embryo -> mature sporophyte plant -> sporogenous cells -> meiosis -> spores - spores -> mature gametophyte plants -> archegonia OR antheridia -> eggs OR sperm cells

Apical Meristem

An area of dividing tissue, located at the tip of a shoot or root, that gives rise to primary tissues; apical meristems cause an increase in the length of the plant body - seedless vascular plants are useful in studying how apical meristems give rise to plant tissues

Embryos

Embryophytes develop form multicellular embryos enclosed within maternal tissues

Whisk Ferns

Fern relatives lacking true roots and leaves; characterized by dichotomous branching - yellow balls in picture are sporangia

Horestails

Fern relatives with hollow, jointed stems, to which tiny leaves (reduced megaphylls) are attached in whorls

Dichotomous Branching

In botany, a type of branching in which one part always divides into two more or less equal parts

Strobilus

In certain plants, a conelike structure that bears sporeproducing sporangia - e.g. Horestails

Plants

Members of the archaeplastid supergroup, distinguished by development of sporophytes from multicellular embryos enclosed in maternal tissues; also called land plants. - Monophyletic group

How does one distinguish between megaphylls and microphylls?

Microphylls are small, with a single vascular strand; megaphylls are typically larger and each possesses more than one vascular strand.

How are mosses, liverworts, and hornworts similar? How is each group distinctive?

Mosses, liverworts, and hornworts lack vascular tissue and share similar gametophyte dominant life cycles. They most obviously differ in their body forms: mosses (leafy gametophytes), liverworts (thalloid or leafy gametophytes), and hornworts (thalloid gametophytes that give rise to sporophytes that exhibit indeterminate growth).

Ferns

One of a phylum of seedless vascular plants that reproduce by spores produced in sporangia; ferns undergo an alternation of generations between the dominant sporophyte and the gametophyte (Prothallus)

Homospory

Production of one type of n spore that gives rise to a bisexual gametophyte - characteristic of bryophytes, horsetails, whisk ferns, and most ferns and club mosses

Gametangia

Special multicellular or unicellular structure of plants, protists, and fungi in which gametes are formed

Sporophyte Generation

The 2n, spore-producing stage in the life cycle of a plant

Microspores

The n spore in heterosporous plants that gives rise to a male gametophyte

Gametophyte Generation

The n, gamete-producing stage in the life cycle of a plant

Thallus

The simple body of an alga, fungus, or nonvascular plant that lacks root, stems, or leaves e.g.: Liverwort

Phloem

The vascular tissue that conducts dissolved sugar and other organic compounds in plants

Xylem

The vascular tissue that conducts water and dissolved minerals in plants

Microphyll

Type of leaf found in club mosses; contains one vascular strand - probably evolved from small, projecting extensions of stem tissue

Indeterminate Growth

Unrestricted growth, as for example, in stems and roots. - Unique feature of Hornworts

Lignin

Vascular plants only - A substance found in many plant cell walls that confers rigidity and strength, particularly in woody tissues

Stomata...

allow gas exchange for photosynthesis

The waxy layer that covers aerial parts of plants is the

cuticle

These plants have hollow, jointed stems that are impregnated with silica.

horsetails

Gemmae

iny balls of tissue used for asexual reproduction by liverworts

The green, gametangia-bearing moss plant

is the haploid gametophyte generation

Land Plant Ancestry

land plants probably descended from a group of green algae called charophytes or stoneworts

Bryophytes

nonvascular plants including mosses (Bryophyta), liverworts (Hepatophyta), and hornworts (Anthocerophyta) - meaning no xylem or phloem