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Transcript of Plants
Conifers are the most common among the gymnosperms with 588 known species.
All conifers bear seeds inside cones.
They're one of the oldest groups of plants, with araucaria-like trees dating back 290 million years ago.
They're are pollinated by wind.
Cycads are known to have lived in the Permian era, over 200 million years ago.
Woody plants which have roots, a stem, leaves and cones.
They are unique to the other gymnosperms because they produce motile sperm cells.
Unlike conifers that are pollinated by wind, cycads are pollinated by beetles.
There is only one species of ginkgo living today known as Ginkgo biloba or maidenhair tree.
Like the cycad, ginkgos have motile sperm.
Leaves of Ginkgo are well-represented in the fossil record and confirm that the plants were abundant 170 million years ago
Although there is only one species left of ginkgo, the ginkgo biloba is the oldest known living tree species with fossils dating back 270 million years.
Seedless Vascular Plants
evolved from ancestral algae around 475 mya
cannot grow very large because of the lack of support tissue
Background and basic characteristics
Most likely originate from the time period between the Devonian and Carboniferous eras
by evolving vascular tissue, the ancestors of these seedless vascular plants decreased carbon dioxide removal from the atmosphere
share some characteristics with non-vascular plants
branched sporophytes that are not dependent on gametophytes for nutrition
prehistoric seedless vascular plants did not completely decay and eventually turned into coal deposits
evolved during the carboniferous era
commonly referred to as mosses, but they are not true mosses due to their vascular systems
were previously classified into subgroups, but are now recognized as one group
more closely related to seed plants than to lycophytes
come from the family Isoetidae, which contains two genera and 77 species
aquatic or moist terrestrial plants
usually grow as a circle of leaves originating from a central rhizome
wiry roots emerge from this central rhizome
sporangia occur on the inside of inflated leaf bases
Characteristics of All Plants
have a generation-based reproductive cycle that oscillates between haploid and diploid stages
Have a gametophyte and sporophyte version of the same plant
develop a cuticle- a waxy outer covering made up of polyester and wax
Walled spores that are produced in sporangia
club mosses, spike mosses, and quillworts
ferns, horsetails, whisk ferns and relatives
The most widespread seedless vascular plants with over 12,000 species
sporophytes have horizontal stems that make fronds that are divied into leaflets
almost all are homosporous
have stalked sporngia with springlike devices that hurl spores several meters
contain only 15 surviving species, all of the genus
found in marshy places and along streams
name refers to their brushy appearance
homosporous, have cones that release spores, giving rise to bisexual gametophytes
also called arthropods due to their jointed stems
the stem is the main photosynthetic organ
Whisk Ferns and Relatives
Whisk ferns and their relatives are grouped into one clade containing mostly epiphytes
lack true roots
called "living fossils" due to their resemblance to the fossils of the earliest vascular plants
closely related to ferns but lost their roots during the process of evolution
sporophytes have dichotomously branching stems
stems have scale-like outgrowths that contain no vascular tissue
yellow knobs on stems consist of three combined sporangia
consists of one family, the Selaginellaceae, which contains one genus and 700 species
grow in moist, shaded habitats normally, but can exist in deserts
lack true roots
some are epiphytes
Lycopodiaceae family (contains 2-5 genera and 450 species)
club mosses make up the most common genus, Lycopodium
terrestrial, perennial, evergreen plants
haploid sperm are produces in a clublike structure known as a strobilus
Gymnosperm literally means "naked seed". The root word gumnos means "naked" and sperma means "seed".
A gymnosperm is a vascular plant that produces seeds lacking an outer fruit.
Gymnosperm seeds are "naked" because they lack ovary walls.
A common example of this type of seed is found in cones.
The male cones produce sperm, which are contained in pollen grains.
The female cones produce eggs, which are contained in the ovules and the seed grows inside the female cone.
There are four different phyla of gymnosperms
A plant that has a complex vascular tissue system made up of two tissue types, xylem and phloem
the sporophyte is the larger and more complex plant as opposed to the gametophyte
lignified tissue strengthens plant stems, allowing vascular plants to grow taller than their non-vascular cousins
What is an Angiosperm?
Plant's closest relatives are the charophytes, a type of green algae
Distinctive traits that suggest Charophytes are the closest relatives of Plants
Rosette-shaped cellulose synthesizing complexes
Both plants and charophytes have PETAL shaped arrangements of protein in their plasma membrane that synthesize cellulose
Algae that are not charophytes have LINEAR arrangements that synthesize cellulose
Both Charophytes and plants contain enzymes that reduce the loss of products due to photorespiration
Other algae do not have this
Formation of a Phragmoplast
A phragmoplast forms in only land plants and specific charophytes. A phragmoplast is a group of microtubules that forms between between the daughter nuclei of a dividing cell. The cell plate develops across the phragmoplast
Gymnosperms produce both male and female cones.
Warning: Contains no vascular tissue, ie xylem or phloem
"leaves" usually only one cell thick
Sporophytes usually elongated and visible
Sporophytes turn brown when mature and ready to release spores
stomata present on sporophyte
The horn refers to the shape of the sporophyte
gametophytes grow close to the ground
Usually the first to colonize moist soils; they have a symbiotic relationship with nitrogen fixing cyanobacteria
stomata present on sporophytes
Makes up about 20% of the species
The gametophyte is "thalloid" shaped, or "leafy"
leafy liverworts far outnumber thalloid liverworts
no stomata present on sporophytes
Terms To Know
: the gamete-producing haploid phase, which produces other haploid gametes by mitosis. It is the dominant form in bryophytes
: the asexual and diploid phase, producing haploid spores from which the gametophyte arises by meiosis. It is the dominant form in vascular plants
: multicellular organs where spores are produced. Composed of diploid cells called sporocytes that undergo meiosis to produce haploid spores
: Plants that use other plants as a substrate but are not parasites
Spores: a small, typically one celled haploid reproductive unit that gives rise to a gametophyte
Rhizoids: root-like filament on the underside of some lower plants that anchors the plant and conducts water
Seta: the stalk that supports the capsule of the plant
Terms for Nonvascular Plants
Terms for Vascular Plants
Xylem: tissue made up of tube shaped cells that transports water and minerals from the roots of the plants to its leaves
Phloem: vascular tissue that conducts sugars and other metabolic products downward from the leaves
Terms for Seedless Vascular Plants
What is a gymnosperm?
Recent studies have shown that Gnetales are the closest relatives to angiosperms.
There are three highly distinctive monotypic
More closely related to angiosperms than any other extant seed plant.
Woody shrub plants
Represents the basal group in gnetophyte evolution
Found only in the Namib Desert of Angola and Namibia
Can live over 1000 years.
unbranched stem, large taproot, and massive woody crown with only 2 permanent leaves.
most developed roots as opposed the the nonvascular rhizoids
Most have developed leaves, which increase the surface area of plants as well as their photosynthetic qualities
Sporophylls are the modified leaves that bear sporangia, the organs of plants that produce spores
Homosporous: produces only one type of spores that have both male and female characteristics
Heterosporous: two types of spores: male microspore and female megaspores
a flowering plant, which forms seeds inside a protective chamber called an ovary
Background and Basic Characteristics
angiosperms account for nearly 90% of all living plant species
classified under a single phylum called Anthopytha
originated during the late Mesozoic era at least 140 million years ago
Until 1990s, flowering plants were divided into two groups based on the number of cotyledon or seed leaves
- members of three early-diverging lineages. Only about 100 species.
- distinguished by branching-veined leaves, single pore pollen, and trimerous flowers. Only about 8,000 species.
two reproductive structure evolved
a short stem with multiple leaves, which its structure specializes in sexual reproduction
direct pollination from insects and animals
wind dependent pollination
four floral organs made from modified leaves (sporophylls)
helps protect and enclose a flower bud
located at the base of the flower
often the colorful parts that attract pollinators
wind-dependent flowers lack brightly colored petals
located inside the sepals
pollen-producing reproductive organ
consists of a filament and a terminal sac, or anther
produce microspores that develop into pollen grains containing male gametophytes
ovule-producing reproductive organ
consists of stigma, style, and ovary
stigma ensure adhesion of pollen to the plant
style leads from the stigma to the ovary at the carpel's base
make megaspores to produces female gametophyte
a mature ovary that protects dormant seed and aid in dispersal
fleshy ( oranges, plums) or dry ( beans, nuts)
fruit adaptations enhance their seed dispersal
water (ex: coconuts)
wind - parachute or propellers
brightly colored and sweet tasting to attract pollinators
plants use different parts of themselves to produce a new plant
stolons (runners) are stems that grow horizontally above ground, which have buds that grow into new plants
tubers are thick roots that grow new plants from buds, which are developed at the base of the stem
plants usually do not require color or fragrance
We were going to put more plant jokes, but all of the ones we found were too corny
After landing on the stigma, a pollen grain produces a pollen tube that extends toward the ovary
double fertilization results from the discharge of two sperm cells from the pollen tube into the embryo sac
one sperm fertilizes the egg to form the zygote, and the other sperm fertilizes the central cell to form the triploid (3n) nutrient-rich tissue
Evolution of Nonvascular plants
1. Liverworts are the oldest lineage: stomata evolved once in the hornworts, mosses and vascular plants
2. Hornworts or mosses are the oldest lineage: Stomata evolved in all plants but was lost in the liverworts
3. Hornworts are the deepest lineage and mosses are the closest relatives of vascular plants: Hornworts acquired stomata independently of mosses and vascular plants
What are the four phyla of gymnosperms?
Which phylum has only one living species left and what is it called?
Which gymnosperm phyla have motile sperm?
What are the two phyla of seedless vascular plants?
A) Scallia and Pterodactyla
B) Selligellaceae and Byrophyta
C) Pterophytes and Lycophytes
D) Gymnosperms and Angiosperms
What is the most widespread family of seedless vascular plants?
B) Club mosses
D) Whisk Ferns and Relatives
How many different theories of non-vascular plant evolution are there?
All angiosperms are classified under a single phylum called...