Term
Land plants
descend from a single common ancestor |
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Definition
Land plants are monophyletic,
-all descend from a single common
ancestor.
One synapomorphy:
--development from an embryo protected
by tissues of the parent plant.
--Also called embryophytes. |
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Term
| Land plants retain derived features they share with green algae: |
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Definition
Land plants retain derived features they share with green algae:
-Chlorophyll a and b.
-Starch as a storage product.
-Cellulose in cell walls. |
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Term
| Plants” can be defined in several ways. |
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Definition
“Plants” can be defined in several ways.
Streptophytes include
--land plants and a
--paraphyletic group of green algae
--all retain egg within the parent body.
Green plants:
--streptophytes plus all other green
algae.
--All have chlorophyll b.
This textbook: “plants” refers only to land plants. |
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Term
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Definition
Vascular plants, or tracheophytes (seven clades)—
all have conducting cells called tracheids.
The seven groups of vascular plants constitute a clade. |
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Term
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Definition
Nonvascular plants: (three clades)
—liverworts
-hornworts
-mosses.
These groups do not form a clade. |
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Term
| the sister clade of land plants. |
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Definition
Charales is the sister clade of land plants.
Synapomorphies:
--Plasmodesmata
--Branching, apical growth
--Retention of egg in parent
Coleochaetales are also closely related to land plants. |
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Term
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Definition
| A synapomorphy is a characteristic shared by two or more taxa which was derived from their common ancestor |
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Term
| What did plants need to move to land? |
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Definition
Plants first appeared on land between 400–500 million years ago.
Adaptations were needed to survive in a dry environment.
--Large plants needed a way to
transport water to all parts of
the plant.
---Land plants also needed support and
methods to disperse gametes. |
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Term
| Characteristics of land plants: |
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Definition
Characteristics of land plants:
--The cuticle.
--Gametangia enclosing gametes.
--Embryos in a protective structure.
--Pigments that protect against UV
radiation.
--Spore walls containing sporopollenin.
--Mutualistic relationships with fungus. |
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Term
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Definition
| The cuticle, composed of waxy lipids, prevents water loss by evaporation |
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Term
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Definition
Ancient plants contributed to soil formation.
Acids secreted by plants help break down rock.
Organic material from dead plants contributes to soil structure. |
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Term
| Today’s nonvascular plants are thought |
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Definition
Today’s nonvascular plants are thought to be similar to the first land plants.
They grow in moist environments in dense mats.
They are small, there is no system to conduct water from soil to plant body parts. |
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Term
| how to nonvascular plants get water & minerals? |
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Definition
Growth pattern of nonvascular plants allows water to move through mats by capillary action.
Minerals can be distributed through the small plants by diffusion. |
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Term
nonvascular plants grow --
oftern with fungi |
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Definition
Many can grow on marginal surfaces, including tree trunks, rocks, even buildings.
Have a mutualistic relationship with fungi called glomeromycetes.
The earliest plants were colonized with these fungi—they promote absorption of water and minerals. |
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Term
| All land plants have a life cycle with alternation of generations. |
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Definition
All land plants have a life cycle with alternation of generations.
Includes
multicellular diploid (sporophyte) and
multicellular haploid (gametophyte) individuals |
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Term
| describe alternations of generations |
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Definition
Cells in sporangia undergo meiosis to produce haploid, unicellular spores.
Spores develop into a multicellular haploid plant—the gametophy—by mitosis.
Gametophytes produce haploid gametes by mitosis.
Fusion of gametes (syngamy or fertilization) results in a diploid zygote.
The zygote develops into the multicellular sporophyte. |
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Term
| Reduction of the gametophyte generation is a major theme in plant evolution. |
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Definition
Reduction of the gametophyte generation is a major theme in plant evolution.
In nonvascular plants: the gametophyte is larger, longer-lived, and more self-sufficient than the sporophyte.
In plants that appeared later, this is reversed. |
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Term
| In nonvascular plants, the gametophyte generation is |
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Definition
In nonvascular plants, the gametophyte generation is photosynthetic.
The sporophyte may or may not be photosynthetic, but is always nutritionally dependent on the gametophyte, and is permanently attached. |
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Term
| In nonvascular plants, the gametophyte generation is |
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Definition
In nonvascular plants, the gametophyte generation is photosynthetic.
The sporophyte may or may not be photosynthetic, but is always nutritionally dependent on the gametophyte, and is permanently attached. |
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Term
| The haploid gametophyte produces gametes in specialized sex organs |
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Definition
The haploid gametophyte produces gametes in specialized sex organs; gametangia.
Female: archegonium; produces one egg.
Male: antheridium; produces many sperm with two flagella each |
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Term
| how sperm and eggs get together |
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Definition
Sperm must swim to archegonium, or be splashed by raindrops.
Egg or archegonium releases chemical attractants for sperm.
Cells in archegonium break down to form a water-filled canal for sperm to travel through.
Water is required for all these events |
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Term
| when sperm and eggs get together |
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Definition
Egg and sperm form a diploid zygote.
Zygote develops into a multicellular, diploid sporophyte embryo.
Base of archegonium grows to protect embryo during early development.
Sporophyte remains attached to gametophyte by the “foot.” |
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Term
| plants and the fossil record |
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Definition
Nonvascular plants evolved before vascular,
but vascular plants appear earlier in the fossil record—
the vascular tissue fossilized more easily.
Recently, fragments of ancient liverworts have been discovered. |
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Term
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Definition
The vascular system consists of tissue specialized for the transport of materials.
--Xylem conducts water and minerals from soil up to aerial parts of plant.
Some cells have lignin—provides
support.
--Phloem conducts products of
photosynthesis through plant.
--Tracheids are the main water-
conducting element in xylem.
--Angiosperms have tracheids plus
a more efficient system of
vessels and fibers |
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Term
| Evolution of tracheids had two important consequences |
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Definition
Evolution of tracheids had two important consequences:
--Transport of water and minerals.
--Rigid structural support (not needed in aquatic green algae). |
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Term
| vascular plants and their sporophytes |
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Definition
Vascular plants also have a branching, independent sporophyte.
Mature sporophyte is nutritionally independent from the gametophyte |
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Term
| First vascular plants were successful on land because of |
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Definition
First vascular plants were successful on land because of
--the cuticle,
--protective layers for the gametangia ---the absence of herbivores.
First fossils are from the Silurian |
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Term
| what appeared during the devonian |
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Definition
During the Devonian,
--the lycophytes (club mosses) and
--pteridophytes (horsetails and ferns) appeared.
Amphibians and insects were also arriving on land. |
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Term
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Definition
Trees appeared in the Devonian and dominated in the Carboniferous.
Forests of lycophytes, horsetails, and tree ferns flourished in swamps.
Plant parts that were buried and subjected to heat and pressure became coal. |
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Term
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Definition
During the Permian, the continents came together to form Pangaea.
Extensive glaciation occurred late in the Permian.
Lycophyte–fern forests were replaced by gymnosperms. |
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Term
| Earliest vascular plants (now extinct) |
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Definition
Earliest vascular plants (now extinct):
Rhyniophytes (Silurian)
--had dichotomous branching,
--but lacked leaves and roots.
They were anchored by
--rhizomes (horizontal portions of
stem) and
--rhizoids (water-absorbing filaments). |
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Term
________also appeared in the Silurian.
________ appeared in the Devonium.
These two groups had what? |
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Definition
Lycophytes also appeared in the Silurian.
Pteridophytes appeared in the Devonian.
These groups had
--true roots and leaves, and
--two types of spores |
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Term
what form a clade called euphyllophytes?
Their synapormorphies include what? |
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Definition
Pteridophytes and seed plants form a clade called euphyllophytes.
Synapomorphies include
overtopping growth, which is
—new branches grow beyond the others
—an advantage in the competition for light. |
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Term
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Definition
Roots probably arose independently in the lycophytes and euphyllophytes.
Probably originated from a rhizome or stem.
Underground and aboveground stems would be subjected to very different selection pressures; the two have evolved distinctive structures. |
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Term
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Definition
Leaf:
--a flattened photosynthetic structure
arising from a stem or branch;
--has true vascular tissue.
Two types:
--microphylls and
--megaphylls. |
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Term
| Club mosses (lycophytes) have what kind of leaves... |
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Definition
Club mosses (lycophytes) have microphylls: small, simple leaves, usually one vascular strand.
May have originated as sterile sporangia. |
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Term
| Pteridophytes and seed plants have what kind of leaves... |
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Definition
Pteridophytes and seed plants have
--megaphylls—larger and more complex.
May have arisen from a dichotomously branching stem with overtopping growth.
Megaphylls evolved more than once. |
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Term
Small megaphylls first appeared in the _________
Large megaphylls did not appear until the _______
What is one theory about this? |
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Definition
Small megaphylls first appeared in the Devonian.
Large megaphylls did not appear until the Carboniferous.
One theory: high CO2 concentrations in the Devonian prevented development of stomata.
Stomata allow heat to be lost by the evaporation of water. Large leaves with no stomata would have resulted in overheating. |
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Term
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Definition
The most ancient vascular plants were homosporous—a single type of spore.
The spores produce one type of gametophyte that has both archegonium and antheridium. |
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Term
| Heterosporous plants produce two types of spores: |
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Definition
Heterosporous plants produce two types of spores:
Megaspore develops into female gametophyte—megagametophyte.
Microspore develops into male gametophyte—microgametophyte.
Megaspores are produced in small numbers in megasporangia.
Microspores are produced in large numbers in microsporangia.
Heterospory evolved several times |
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Term
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Definition
Liverworts: Hepatophyta—9,000 species.
Some have leafy gametophytes; some have thalloid gametophytes.
Sporophytes very short—a few mm.
A stalk raises the simple sporangium above ground level to allow spores to be dispersed.
Liverworts also reproduce asexually:
By simple fragmentation of the gametophyte;
And by gemmae—lens-shaped clumps of cells in gemmae cups. Gemmae are dispersed by raindrops. |
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Term
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Definition
Hornworts: Anthocerophyta—100 species.
Gametophytes are flat plates of cells.
Have stomata, which do not close |
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Term
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Definition
Hornwort cells have a
--single, large chloroplast.
--The sporophyte has no stalk;
but has a basal region capable of
infinite cell division.
--Sporophytes can grow up to 20 cm.
--Hornworts have internal cavities
filled with nitrogen-fixing
cyanobacteria. |
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Term
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Definition
The mosses: Bryophyta—15,000 species.
Probably sister to the vascular plants.
Gametophyte begins as a branched, filamentous structure—the protonema.
Some filaments are photosynthetic, others are rhizoids that anchor the protonema.
Tips of photosynthetic filaments form buds which produce the leafy moss shoots. |
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Term
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Definition
Moss sporophytes and vascular plants grow by apical cell division—
a region at the growing tip provides an organized pattern of division, elongation, and differentiation. |
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Term
| some moss gametophytes are too large to depend on diffusion for water transport. |
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Definition
Some moss gametophytes are too large to depend on diffusion for water transport.
Cells called hydroids die, and provide channels in which water can travel.
Hydroids may be the progenitor of tracheids. |
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Term
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Definition
Sphagnum grows in swampy places.
The upper layers of moss compress lower layers that are beginning to decompose, forming peat.
Long ago, continued compression led to the formation of coal. |
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Term
| In the seedless vascular plants, the large sporophyte is.... |
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Definition
c independent of the small, short-lived gametophyte.
The single-celled spore is a resting stage.
Must have water for part of the life cycle—for the flagellated, swimming sperm. |
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Term
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Definition
The lycophytes:
-club mosses,
-spike mosses, and
-quillworts:
1,200 species.
--Roots and stems have dichotomous branching;
--leaves are microphylls |
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Term
| club mosses and their sporangia |
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Definition
Some club mosses have sporangia arranged in clusters called strobili.
Others have sporangia on upper leaf surfaces—sporophylls. |
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Term
Lycophytes...
when dominant
coal |
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Definition
Lycophytes were dominant during the Carboniferous.
One type of coal—cannel coal—is formed from the spores of a tree lycophyte Lepidodendron. |
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Term
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Definition
| In pteridophytes and all seed plants, growth is overtopping. |
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Term
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Definition
Horsetails: Fifteen species in one genus—Equisetum.
--Silica in cell walls—“scouring
rushes.”
--Have true roots;
--sporangia are on short stalks called
sporangiophores.
--Leaves are reduced megaphylls in
whorls.
--Each stem segment grows from the base. |
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Term
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Definition
Whisk ferns: Fifteen species in two genera.
--No roots
--but well-developed vascular system.
Psilotum flaccidum has scales instead of leaves.
Tmesipteris has flattened, reduced megaphylls. |
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Term
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Definition
Ferns: 12,000 species. About 97 percent are in a clade—
leptosporangiate ferns
--sporangia walls only one cell thick,
--borne on a stalk.
--Sporophytes have true roots, stems,
and leaves.
Fern leaf starts development as a coiled “fiddlehead.” |
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Term
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Definition
Fern life cycle:
--Spore mother cells in sporangia form
haploid spores by meiosis.
--Spores can be blown by wind and
develop into gametophyte far from
parent plant.
--Fern gametophytes produce antheridia
and archegonia, not always at
the same time or on the same
gametophyte.
--Sperm swim through water to
archegonium to fertilize egg.
--Zygote develops into independent
sporophyte. |
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Term
| general info on most ferns and their growing |
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Definition
Most ferns are in shaded, moist environments.
Tree ferns can reach heights of 20 m.
Sporangia occur on undersides of leaves in clusters called sori. |
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Term
most ferns and their spores
some ferns and fungus |
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Definition
Most ferns are homosporous;
two groups of aquatic ferns are heterosporous.
Some genera have a tuberous gametophyte that depends on a mutualistic fungus for nutrition |
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Term
| DNA research suggests that diversification of modern ferns is.... |
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Definition
DNA research suggests that diversification of modern ferns is fairly recent.
Ferns may have taken advantage of shady environments created by angiosperm trees. |
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