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