Gymnosperms Lecturer: Asst. Prof. Dr. İsmail EKER.
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Transcript of Gymnosperms Lecturer: Asst. Prof. Dr. İsmail EKER.
GymnospermsLecturer: Asst. Prof. Dr. İsmail EKER
Tracheophytes
Seedless Seeded
Ferns use spores
Gymnosperms Angiosperms
“naked” or exposed
seeds
Flowers produce fruit / enclosed
seeds
Evolution Of Land PlantsREMEMBER:• Terrestrial plants evolved from a green
algal ancestor (Charophytes)• The earliest land plants were nonvascular,
spore producers (bryophytes)• Ferns were the 1st vascular, spore
producing plants• Gymnosperms & angiosperms were the 1st
vascular, seed plants
Seeds vs spores
• Seeds are better than spores because spores have a short lifetime.
• Spores are thinner walled and more vulnerable to pathogens and damage.
Classification of Seed Plants
A. There are five phyla of extant seed plants: 1. Four of the phyla have naked ovules borne on
modified sporopylls. These are called "gymnosperms" = “naked seed”. Mostly Evergreen plants
2. In the remaining phylum (Anthophyta) the ovules are enclosed within a protective structure called an ovary (flower like reprodcutive structures). Mostly Decidious plants
PHYLA OF GYMNOSPERMS
Cycadophyta (cycads)
Ginkophyta (maidenhair tree or Ginko)
Coniferophyta or Pinophyta (conifers)
Gnetophyta (Gnetophytes)
GYMNOSPERMS: Non-Flowering Seed Producers
Phylum Coniferophyta1. Most common gymnosperms are Conifers (about 70
genera & 630 species) 2. Conifers have leaves called needles or scales which
have a reduced surface area and thick waxy coat on the needle to reduce water loss and prevents freezing.
3. Sporophylls arranged around a stem4. Cones usually woody, sometimes soft & fleshy5. Common members include the pine, fir, spruce, yew,
cypress, juniper, cedar and redwood.6. Conifers are most common at the higher latitudes,
towards the poles7. Conifers arose by 300 million years ago
Coniferophyta• Con- gr. cone, fer- L. bear.• Tracheids, but no vessel elements.• Sperm not motile.• Ovulate (female) & microsporangiate (staminate=male)
cones on same plant (Monoecius).
Male &
Female
Cones
(Do not produce flowers or fruit)
Oldest living trees: bristlecone pine (Pinus longaeva)
White Mountains of California
up to 5000 years old!
!
Tallest living trees: redwoods (Sequoia sempervirens) may reach 112 m tall
cypress family Cupressaceae
coastal California and the southwestern corner of coastal Oregon
!
Most massive trees: giant sequoia (Sequoiadendron giganteum) may reach diameters of 17 m
Sierra Nevada/California
!
Alternation of generations in seedless and seed plants
Meiosis
Fertilization
KeyHaploidDiploid
Gametophytes
Egg
Sporophyte
Meiosis
Gymnosperms(e.g., pine)
Ovulatecone
Pollencone
Megasporangium
Microsporangium
Megasporangia and microsporangia are found in separate cones
Meiosis produces spores and begins the haploid generation
Megasporocytes (2n) are the cells within megasporangia that undergo meiosis to produce megaspores (n)
Microsporocytes (2n) are the cells within microsporangia that undergo meiosis to produce microspores (n)
Megasporocyte
Microsporocyte
Meiosis
Fertilization
HaploidDiploid
Gametophytes
Egg
Sporophyte
Meiosis
Gymnosperms(e.g., pine)
Ovulatecone
Pollencone
Megasporangium
Microsporangium
Megasporocyte
MicrosporocyteEach megaspore develops into a female gametophyte
Each microspore develops into a male gametophyte (a pollen grain)
Megaspore
Pollen
A pollen grain gains access to a female gametophyte through a micropyle
Meiosis
Fertilization
HaploidDiploid
Gametophytes
Megaspore
Sporophyte
Meiosis
Gymnosperms(e.g., pine)
Ovulatecone
Pollencone
Megasporangium
Microsporangium
Megasporocyte
The female gametophyte contains 2 or 3 (to 5) archegonia, each with 1 egg cell
Two cells of the male gametophyte are sperm
Microsporocyte
Pollen
Archegonium
Egg nuclei
Sperm nuclei
Meiosis
Fertilization
KeyHaploidDiploid
Gametophytes
Embryo
Sporophyte
Meiosis
Gymnosperms(e.g., pine)
Ovulatecone
Pollencone
Fertilization (union of 1 egg and 1 sperm) produces an embryo
Megasporangium
Microsporangium
Megaspore
Microsporocyte
Pollen
Megasporocyte
Archegonium
Egg nuclei
Sperm nuclei
Meiosis
Fertilization
KeyHaploidDiploid
Gametophytes
Embryo
Sporophyte
Meiosis
Gymnosperms(e.g., pine)
Ovulatecone
Pollencone
Fertilization (union of 1 egg and 1 sperm) produces an embryo
Megasporangium
Microsporangium
Seed
Seedling
Embryos develop within seeds
Seeds germinate and embryos become seedlings
Megaspore
Microsporocyte
Pollen
Megasporocyte
Egg nuclei
Sperm nuclei
Archegonium
Gymnosperm - heterosporyIndependent and dominant sporophyte
megaspores
mega-gametophyte
eggs
zygote
embryo
meiosis
n2n
sperm
microspores
micro-gametophyte
Pine life cycle
Phylum Ginkgophyta• 1 genus & 1 species - Ginkgo biloba
(the maidenhair tree)• Yin- ch. silver, hing- ch. Apricot• does not bear cones• Tracheids, but no vessel elements• Dioecious (Ovulate &
microsporangiate cones on separate plants; fleshy-coated seeds)
• males are more commonly planted, females produce seeds that have a nasty odor
• pollination is by wind.• multiflagellated swimming sperm• Fan-shaped leaves (Veins nearly
parallel with dichotomous branching)Ancient group unchanged in 200 million years
Ginkgo biloba – a “living fossil”, Ginkgo has not been found in the wild and would probably be extinct but for its cultivation in ancient Chinese and Japanese gardens. Ancient trees (to 3,000 years old!) found in China & Japan, in temple gardens and places tended by people.
Female flowers (2 naked ovules on a peduncle) & seeds
Male flowers
Phylum Cycadophyta• ca. 11 genera (130 spp.)• short shrubs, native to tropical regions
(look like palms)• unbranched trunk (little wood)• usually pinnately compound leaves• loss of axillary branching• dioecious: male and female plants• male and female strobili (cones)• motile, multiflagellate sperm
Look like a palm tree but produce a cone
Cycas revoluta female Cycas revoluta male
“naked” ovules
Ovule-bearing leaf(megasporophyll) of cone Strobilus of a “female” cycad
Phylum Gnetophyta• 3 extant genera: Ephedra (65 spp.); Gnetum (28 spp.);
Welwitschia mirabilis• have some angiosperm-like features (e.g. tracheids and
vessel elements; scalelike, leaflike, broad and leathery leaves; double fertilization)
• Cladistic analyses support placement of the gnetales (or some portion of them) as outgroups for the flowering plants
• With angiosperm-like broad leaves, but still retaining cones, the Gnetophytes are another very close link to the Angiosperms.
• Sperm not motile.• Pollen tube fuses with egg cell.• Ovulate & microsporangiate cones compound and mostly borne
on separate plants (Dioceous).
Welwitschia
two huge leathery leaves-a strange plant native to deserts of Namibia, SW Africa- Live up to 2000 years in these extreme conditions!- Only makes two leaves throughout its life. It takes water from sea mist
Gnetum
– leaves angiosperm-like– vessels in the xylem
• considered an angiosperm characteristic• tropical vines, trees, shrubs with opposite leaves
that look like angiosperms!
Ephedra– Mormon tree– common desert shrub– reduced scale-like leaves
Significance of gymnosperms• Ecological importance:• Provide food and habitat for wildlife• Forests prevent soil erosion• Reduce greenhouse-effect gasses• Economic and commercial importance:• Lumber for wood, paper, etc.• Resins – wood, furniture, etc.• Ornamental plants (trees, landscaping)• Food – pine nuts (pesto-pine nut, bacil, garlic,
sold, cheese, olive oil)
Gymnosperms of TurkeyConiferophyta
Abies (Köknar, Göknar)• A. nordmanniana subsp. equitrojana (Kazdağı köknarı) E• A. nordmanniana subsp. nordmanniana (Kafkas köknarı)- Doğu Karadeniz• A. nordmanniana subsp. bornmulleriana (Uludağ köknarı)- Bursa, Bilecik, Batı ve
Orta Karadeniz E• A. cilicica subsp. cilicica (Toros köknarı) – Toroslar• A. cilicica subsp. isaurica (Toros köknarı) – Toroslar E
Picea (Ladin)• Picea orientalis (Doğu ladini) - Karadeniz
Cedrus (Sedir)• Cedrus libani (Lübnan sediri, Toros sediri) –Akdeniz (Elmalı, Amanoslar), Tokat, Afyon
Pinus (Çam)• P. nigra subsp. pallasiana (Karaçam) – Widespread• P. pinea (Fıstık çamı) - Akdeniz sahilleri, Maraş, Bursa, Trabzon, Çoruh, İzmir• P. sylvestris (Sarıçam) – Karadeniz, Doğu ve İç Anadolu, İç Ege• P. brutia (Kızılçam) – Ege ve Akdeniz, Zonguldak, Malatya• P. halepensis (Halep çamı) – Adana/Kozan
Cupressus (Selvi, servi)• Cupressus sempervirens (Adi servi, mezarlık servisi) – Toroslar
Juniperus (Ardıç)• J. drupaceae (Eriksi ardıç) –
• J. oxycedrus subsp. oxycedrus (Katran ardıcı) –
• J. phoenica (Finike ardıcı) –
• J. foetidissima (Kokar ardıç) –
• J. oblonga () –
• J. sabina (Sabin ardıcı) –• J. excelsa (Boylu ardıç) –• J. communis subsp. hemisphaerica• J. communis subsp. Nana
Taxus (Porsuk)• Taxus baccata (Porsuk)
Gnetophyta
Ephedra (Deniz üzümü)• E. campylopsida () –• E. dictachya () –• E. major () –
• !!!– Endemic to South Africa– But, extinct in the wild.– All plants left are males in
gardens! – Propagated by suckers (side
branches).
Encephalartos woodii (Cycadophyta) known only from male plants
A very old bonsaiGinkgo
Ginkgo in fall on Japanese street
• A-bomb resistant!• This tree in Hiroshima,
Japan, was 1.1 km from where the first Atomic bomb was used in 1945.
What’s Wrong With This Picture?
İt is a conifer (cone-bearer) but its not a true “EVERGREEN”
Male Cone
Female Cone
Larix decidua
deciduous coniferous tree