Gymnosperms And Angiosperms i135v

Seed Plants

• Gymnosperms • Angiosperms

Gymnosperms Phylum

Common Name

Approx. # of Species

Ginkgophyta

Ginkgo

1

Cycadophyta

Cycads

130

Gnetophyta

Gnetae

75

Coniferphyta

Conifers

600

Characteristics of Gymnosperms • Vascular tissue present – Phloem and xylem

• Naked seeds • No flowers • Dominant generation: Sporophyte

Gymnosperm Sporophyte • Gametophyte is dependent on sporophyte. • Male cone (pollen cone) – Produce microspores. – Microspores undergo meiosis and eventually produce pollen grains.

• Female cone (ovulate cone) – Produce megaspores. – Megaspores undergo meiosis and eventually produce the archegonia.

Zamia sp.

Ginkgo

Pinus

Pollen grains = immature endosporic male gametophytes

Pollen = immature endosporic male gametophyte

micropyle

pollen grains

pollen grains with tubes

micropyle pollen grains

archegonial chamber

pollination droplet integument meiosis megasporocyte (2n) megasporangium (nucellus) (2n)

integument (2n)

pollination chamber mitosis & differentiation functional megaspore (n)

archegonium (with egg) megasporangium (nucellus) (2n)

female gametophyte (n)

Ovule development in non-flowering Spermatophytes

micropyle

integument (2n)

seed coat radicle

fertilization (sperm + egg)

zygote (new 2n)

mitosis & differentiation

hypocotyl

megasporangium (nucellus) (2n)

} embryo (new 2n)

epicotyl (shoot apex) female gametophyte (n)

cotyledons female gametophyte (n) megasporangium (degenerate)

Seed development in non-flowering Spermatophytes

Young ovule

Mature ovule

Ginkgophyta - Ginkgoales • • • •

Ginkgo biloba Popular street tree Highly branched woody tree Fan-shaped often 2-lobed leaves w/ dichotomous venation • Dioecious • Motile sperm

Macrozamia moorei

Bowenia spectabilis

Z a m i a c e a e

Lepidozamia sp.

Stangeria sp.

Encephalartos sp.

C y c a d a c e a e

Cycas revoluta

Cycas circinalis

Encephalartos sp.

Z a m i a c e a e

Zamia sp.

F, H & I. Ceratozamia sp. ,

Ginkgophyta - Ginkgoales • • • •

Ginkgo biloba Popular street tree Highly branched woody tree Fan-shaped often 2-lobed leaves w/ dichotomous venation • Dioecious • Motile sperm

Ginkgo biloba

Ginkgo biloba With cones but do not bear structures that resemble sporophylls

Ginkgo biloba

Conferophyta- Conifers • Highly branched trees or shrubs with simple leaves • Sperm nonmotile • Evergreen leaves • Needle-like, scalelike, flat blades

Conifer Diversity A. Araucariaceae B-G. Cupressaceae H. Podocarpaceae I-J. Taxaceae

K-L. Pinaceae

Araucariaceae

Cupressaceae

B-C. Cupressus; D. Juniperus; E. Sequoia; F. Sequoiadendron; G. Taxodium

Cuppressus

D. Juniperus E. Sequoia; F. Sequoiadendron; G. Taxodium

Podocarpaceae

Pinaceae

Podocarpaceae

Taxaceae

Taxaceae

Pinaceae: Pinus

Gnetophyta - Gnetales • • • •

3 extant families Thought to be sister group Striate pollen Vessels with pore-like plates

Gnetales

Gnetaceae – Gnetum 28 spp. + monotypic Vinkiella

Ephedraceae - Ephedra (ca. 65 spp.) Morman-Tea Desert shrub

Photosynthetic stems Reduced scale-like leaves

Welwitschia mirabilis Native to Namibia, SW Africa