lect6CUT Gnetophyta

7/23/2019 lect6CUT Gnetophyta

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Kingdom Plantae:

Gymnosperms


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Gymnosperms

Phylum Cycadophyta (cycads) Phylum Coniferophyta (conifers)

Phylum Ginkgophyta (gingko)

Phylum Gnetophyta (gnetophytes)


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Phylum Cycadophyta (cycads)

Small (about 200 species) Mainly tropical

1 U.S. species: found in Florida (Zamia pumila)


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Sporophyte features: Trunk woody

Leaves often spiny and pinnately compound(divided into thin sections: feather-like).

Pinnately compound

leaf

Note

woody

trunk


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Sporophyte features: Pollen made in pollen cones

Encephalartospollen cones


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Sporophyte features: Seeds made in seed cones

Megasporophylls of Cycas Ovule-bearing leaf(megasporophyll) of cone

Encephalartos

female cone


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Sporophyte features: Plants dioecious: separate male and female

individuals.

Cycas revolutafemale Cycas revolutamale


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Phylum Cycadophyta (cycads) Importance:

Some used horticulturally: Cycas revoluta (sago palm)


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Some are endangered in the

wild

Example: South Africa has

40 species, all endangered


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Since 1965, must havepermit to own cycad inSouth Africa

One species extinct in wild.All plants left are males ingardens! Propagated bysuckers (side branches).

Encephalartos woodii, known

only from male plants


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Was a dominant land plant group during dinosaurera (Mesozoic Era).


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Phylum Coniferophyta (conifers)

Largest gymnosperm group: 600 species Dominates biomes in far north and south

temperate zones

Many species with narrow leaves (needle-leaved trees)

Examples: Pines (Pinus), Junipers (Juniperus),Firs (Abies), Cypresses (Taxodium)


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Importance: Also dominant group during Mesozoic Era (dinosaur

time!)


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Extinct Conifers Example, Petrified Forest National Park, Arizona

Most trees there are extinct conifers whose trunks are

mineralized.


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Phylum Coniferophyta (conifers) Importance:

Conifer forest biome(covers large part ofEarths landmass)

Temperate rain forest inWashington/Alaska

Conifer forests occupy high

mountains in North America


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Currently dominant in parts of North(and South) Temperate Zones

Light green

is taiga orboreal forest

(conifers)


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Some communities in southeast dominated by conifers Example, cypress (Taxodium) swamps

Cypress branch Cypress swamp near Monroeville AL


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Some communities in southeastdominated by conifers

Example, cypress (Taxodium) swamps

BIOL 6140 (Plant Ecology) classes explore swamps on field trips


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Importance: Biological records (largest

tree)

Sequoiadendron gigantea(bigtree)

In Sequoia National Park, CA

Base: 102 feet circumference

Weight: 2,145 tons Volume: 52,500 cubic feet.


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Importance:Sequoiadendron gigantea

(big tree)


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Biological records (oldesttree)

Bristlecone Pine (Pinus

longaeva). Found in highmountains of deserts ofCalifornia, Nevada, Utah,Colorado, etc.


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Importance: Oldest tree was 4,950

years. Cut down in 1964by graduate student who

got corer stuck in tree(U.S. Forest Service gavepermission!)

Now oldest known

bristlecone (namedMethuselah) is 4,767years old. Location keptsecret from public!


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Biological records(tallest living tree)

Coast redwood(Sequoiasempervirens)

Grow on coast ofCalifornia/Oregon (ex,Redwood NationalPark)

96% have been logged


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Biological records (tallest livingtree)

Coast redwood (Sequoiasempervirens)

Tallest tree is 368 feet tall!.


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Importance: Biological records (smallest trees?)

Pygmy forest in Mendocino County, CA


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Biological records (smallest trees?)

Pygmy forest in Mendocino County,CA

Hardpan (like cement) forms atabout 1 foot depth

Dry in summer, floods in winter.


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Stress makes conifers (a pineand a cypress species) stunted

The trees on

the right had

about 30 rings

(30 yr old!)


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Phylum Coniferophyta (conifers) Conifers in Southern Hemisphere too

Example, Wollemi Pine (Australia)

Thought extinct, small stand found in in1994. 40 plants! Discoverer

David

Noble


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Conifers: Economic

Importance Harvest for pulp and timber Can cause controversy, especially

when old-growth and clearcuts

involved.


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Conifers: Economic Importance Importance in Alabama: forestry #1 legal

agricultural crop Many pine plantations in southeast.


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Conifers: Economic Importance

Edible (pine nuts are pine seeds) Harvested from several species, including pinyon

pine from western U.S. (shown below).

Pine seeds

Pinyon

pine


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Conifers: Economic Importance

Medicines: example, taxol Antitumor agent. First extracted from bark of Pacific

Yew (Taxus) tree

Now made synthetically.

Pacific Yew, showing

needles and bark


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Importance: Threatened by humans (acid rain and forest decline)

Acid rain areas (below) include some conifer

forests.


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Importance: Acid rain and othersstresses cause forest

decline, weakness

and death of conifertrees

Seen in N. Europe

and N. America.

Damage/death of fir

trees in Tennessee


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Phylum Ginkgophyta (Ginkgo)

Tiny group (1 living species: Ginkgo biloba) Also called maidenhair tree


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Living fossil: Leaf fossils 150 million years old

Photo of modern and fossil Gingko leaves


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May be oldest living species on Earth!

Dinosaurs under a Ginkgo tree in the Mesozoic fall


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Phylum Ginkgophyta (Ginkgo) Today considered extinct in wild

Ancient trees (to 3,000 years old!) found inChina & Japan, in temple gardens and placestended by people.

Ancient temple tree in China


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Phylum Ginkgophyta (Ginkgo) Leaves winter deciduous, fan-shaped, with

dichotomously-branching veins Made on stubby short shoots on branches

Short shoots with

leaf scars


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Phylum Ginkgophyta (Ginkgo) Gingko very useful horticultural tree

Pollution resistant, makes beautiful street tree

Ginkgo in fall on Japanese streetA very old bonsai

Ginkgo


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Phylum Ginkgophyta (Gingko) A-bomb resistant!

This tree in Hiroshima,Japan, was 1.1 km fromwhere the first Atomic

bomb was used in 1945.


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Phylum Ginkgophyta (Gingko) Medical uses:

May improvecirculation, memory

Still under study

Pills of leaf extractworth millions of $/yr.

Ginkgo farm (top) and drying

leaves (bottom)


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Small group (70 species) Only gymnosperms with vessels in xylem

(large, dead water-conducting cells)


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Phylum Gnetophyta (gnetophytes) Three genera (2 mentioned here):

Welwitschiafrom Namib desert (Africa) Odd, only 2 leaves!

Old plant in Namib desertYoung plant grown in pipe

section (long taproot)


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Three genera (2 mentioned here):Ephedrafrom many deserts of world

Shrub is mostly branches (ovules seen on right


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Three genera (2 mentioned here): This shrub was original source of drug

ephedrine

Used as stimulant, weight loss aid, may have

side effects (stroke, etc.).

You can buy

ephedrine on theYou can also find lawyers to help you

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lect6CUT Gnetophyta