Transcript BIO509 Lecture # 17 File

School of Sciences, Lautoka Campus
BIO509 Botany Lecture 17: Other Phyla of
Gymnosperms
Phylum Ginkgophyta
•There is only one living species
if Gingko (from the Chinese
word meaning silver apricot).
•They have characteristic
notched, broad fan-shaped
leaves which look like larger
versions of the maidenhair
ferns.
•Leaves have no midrib or
prominent veins.
•Hair like veins branch
dichotomously.
• Gingko is dioecious – has male and
female reproductive organs on
different individual plants.
• Mature seeds look like small
plums, and are enclosed in fleshy
seed coats.
• The flesh is unrelated to true
fruits.
• Life cycle similar to pines.
• Ginkos are probably extinct in the
wild, but has been preserved in
temple grounds and parks in
China and Japan.
• In North America male plants are
preferred because the seed flesh
(females) has a nauseating odour
and is irritating to the skin.
• In China and Korea, the seeds are
considered a delicacy, and only
enough male plants are kept for
ensure pollination.
The largest Gingko tree in the world is estimated to be
around 1,200 years old. This tree lives at the HidaKokobunji Temple in Takayama, Japan.
Image - Wikimedia commons
Phylum Cycadophyta – the Cycads
• Appearance of a cross between a tree fern and a
palm.
• Slow-growing plants of the
tropics.
• Un-branched trunks which can
grow more than 15m tall
• Crown of largely pinnately
divided leaves.
• Life Cycle similar to conifers but
cycads have flagellated sperms.
• Pollination is generally brought
about by beetles instead of
wind.
Many are facing extinction.
• Cycads are dioecious.
• Most species have pollen
and seed cones on
separate plants.
• Some species have pollen
cones but lack ovulate
cones and have instead
reduced leaves with
ovules attached.
Phylum Gnetophyta
• There are about 70 species (three distinct generaGnetum, Welwitschia and Ephedra).
• They are unique among gymnosperms in that
they have vessels in the xylem
Ephedra
Gnetum
Welwitschia
Genus Ephedra
• Mostly shrubby plants.
• Found in the drier
regions
• Small leaves produced in
twos or threes.
• Stems and branched are
slightly ribbed and
photosynthetic
Genus Gnetum (most common)
• Occurs in the tropics
• Most are vine-like.
• Broad leaves – similar to
flowering plants.
• Leaves opposite,
leathery, dicot-like
• Produce flower- & seedlike structure
Genus Welwitschia
• Stems are only a small distance from the ground in the form of
a large shallow cup that tapers at the base into a long taproot.
• Only produce two leaves throughout their life span.
• Leaves are long but because they are close to the ground they
get damaged easily.
• Only produce two leaves
throughout their life span.
• Plants live very long (100 years).
• Plants are dioecious.
Human and ecological relevance of
Gymnosperms.
• This group is second only to
angiosperms in importance to the
world and to humans.
• Ecological importance—dominant
tree in boreal and temperate
montane forests.
• Conifers dominate large areas of
natural vegetation in the world
(much of it “boreal forest”),
particularly in N. Europe, Asia, and
N. America, and in mountains
elsewhere in temperate areas
Economic importance of conifers
• Timber—for all kinds of uses
• Paper—as pulpwood for making
paper
• Food—various parts are edible
• Chemicals—from the bark, resin,
etc.
Economically important pine species
in Pacific.
Agathis
• Agathis macrophylla
(Pacific kauri, dakua
makadre) most
important native
timber tree.
• Agathis australis (NZ
kauri) - largest tree in
the Pacific?
Pinus carribea
• Most important
timber species in Fiji
Conifers for Food.
• Bark eaten in North
America.
• Needles for antiscurvy tea in
North America.
• Pine nuts were and still are
harvested and sold, and
sometimes sold, for food in
many parts of the world.
Chemicals from Conifers
• Turpentine used as a paint solvent.
• Rosin for waxing musical instruments.
• Pitch or patching canoes and
nowadays for chemicals.
• Tannin for tanning leather.
• Medicines, e.g., Taxol used for treating
breast cancer.
• Aromatic compounds, such as incense
cedar.
• Resins, such as Canadian balsam, used
as adhesives.
• Amber (fossilized conifer resins).
• Juniper berries used flavoring gin.
Questions??