Transcript Biology Conifers

Gymnosperms
Gymnosperm
• Gymnosperm means “naked seed” –
needs the cone to protect it.
Female - Megaspores
• Cones are reproductive structures of
gymnosperm.
• Each gymnosperm species has a
different cone.
• Includes pines, firs, spruces, cedar
cycad and gingkoes.
• Male and female cones are produced
on the same plant.
Male – Microspores
Structure
Roots- anchor the plant into the soil and
absorb and send water up the plant for
photosynthesis.
Pine needles- adaptation in most but not all
conifers to function with less water. an
example of one that doesn’t have pine
needles is the cupressaceae.
Structure
Stem- houses vascular tissues and supports the
rest of the tree.
Vascular tissue
Specialized tissue in plants that transport
water, nutrients and the products of
photosynthesis
Xylem- primarily for water and nutrients
transport, transports water and nutrients
up.
Phloem- primarily for transport of sugars,
transports sugars down and up as needed.
Do male and female cones differ?
Male and Female Cones
Male cones Microspores: smaller and
deteriorate quickly,where pollen sheds,
less woody texture
Female cones Megaspores:The cone scales
each carry two ovules that develop
to seeds, bigger
Reproduction Cycle
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In gymnosperms, the gametophyte
generation takes place in a cone, which
forms on the mature sporophyte plant.
Inside male cones, male spores develop
into male gametophytes, which consists
of several cells enclosed with a grain of
pollen
Inside female cones, female spores
develop into female gametophytes, which
produces an egg inside an ovule.
When the pollen is transferred from a
male cone to a female cone that's when
pollination occurs
If sperm were to travel from the pollen to
an egg so fertilization can occur, a diploid
zygote is the result.
The zygote develops into an embryo
within a seed, which forms from the ovule
inside the female cone
If the seed germinates, it may grow into
a mature sporophyte tree, and it then
repeats the cycle.
Conifer
Conifer, any member of the Pinophyta, class Pinopsida,
order Pinales, made up of living and fossil
gymnospermous plants that usually have needle-shaped
evergreen leaves and seeds attached to the scales of a
woody bracted cone.
Coniferous means cone bearing.
Cones
• All conifers bear seeds inside
cones, woody protective
structures.
• The conifers are a group of about
588 species of trees and shrubs
that include many of the bestknown plants in the world.
•
There are seven families of
conifers. The largest is the Pine
family (232 species), which
includes such familiar trees as
pine, spruce, fir, and larch.
Unfertilized & Fertilized Ovule
Conifer – Trees
• Almost all conifers
are trees, and so
they create
forests that
provide habitat
for wildlife and a
wide variety of
insects, fungi, and
smaller plants.
• Some conifer
forests support
extremely
complex
ecosystems with
very high levels of
biodiversity.
Conifer Forest
• Only have two layers
• another name for coniferous forest is TAIGA
• The canopy layer is made up of tree which grow to a uniform height
between 20m to 30m.
• Trees grow close together.
• The under growth layer has very littler vegetation because of the low
amount of sun light and poor fertility of the soil.
• Conifer forest mainly found in colder areas, northern potion of the
norther hemisphere. Often covering mountainsides.
• Over time the demand of life on the land favored the evolution of
plants as they are more resistant to the drying rays of the sun, more
capable of reproducing without water.