Division Gnetophyta, economic importance, distribution and species in the Philippines

1. Romeo M. Tubongbanua, Jr.
MASTER OF SCIENCE IN BIOLOGY
(TAXONOMY)
Gnetophyta

2. Coniferophyta Cycadophyta Ginkgophyta Gnetophyta
LEAVES Needle-like
(small, long &
narrow)
Compound
leaves
(resembles
palms or ferns)
Fan-shaped
leaves
Broad leaves
like
angiosperms
SEEDS Seeds in cones Seeds in cones Seeds are
completel
Seeds in cones
arranged in
clusters
XYLEM Tracheid Tracheid Tracheid Tracheid &
vessel
elements
PHLOEM Sieve tubes Sieve tubes Sieve tubes Sieve tubes &
companion
cells
TYPE OF
PLANT
Monoecious Dioecious Dioecious Monoecious or
Dioecious
COMPARISON OF STRUCTURES IN
GYMNOSPERMS

3. Gnetophyta
Division – Gnetophyta
Subdivision – Gnetophytina
Class – Gnetopsida
Subclass – Gnetidae
Order – Gnetales

4. DISTINGUISHING
CHARACTERISTICS
• presence of both tracheids and vessel
elements in their xylem tissue
• a tube grows from the eggs to unite with the
pollen tubes in order for fertilization to take
place between the gametophytes. The sperm
themselves are not motile, like we see in the
cycads and gingko.
• undergoes double fertilization, however no
endosperm forms and the second egg
fertilized disintegrates.

5. FEATURES (SOME ARE COMMON WITH
FLOWERING PLANTS)
• Vessel elements in the vascular system not in
other gymnosperms
• Both Welwitschia and some Gnetum species are
pollinated by insects
• Flower like structures on male cones of
Welwitschia
• Nectar-produced on the tip of the cones rather
in flower
• Most are considered dioecious

6. Distribution, separated by genus:
Green –Welwitschia
Blue – Gnetum
Red – Ephedra
Purple – Gnetum and Ephedra range overlap

8. Welwitschia
Grows in the deserts of Namibia and
Angola (distribution coincides with the fog
belt); This is a plant of remarkably bizarre
habits and survives in very harsh
localities.
The plant was discovered by Austrian
botanist Friedrich Welwitsch.

9. • Welwitschia has just two strap like leaves that grow
continuously, but most leaves break up in the harsh desert
environment and become tatty and brown at the ends..
they are evergreen, a single pair and generally broad and
flat.
• Plant resembles a woody carrot. The stem is exceedingly
fibrous and has a prominent, thick, corrugated periderm.
Unequal growth causes the stems of these plants to
become weirdly distorted and there are only two strap-
shaped leaves, growing from a terminal groove in the
photosynthetic tissue of the stem.
• Uses its millions of stomata on the surface of it's large
leaves. to absorb water from fog through millions of
stomata from there the water moves to the rest of the
plant.

10. GROWTH HABIT IS UNIQUE: The apical growth
point of the stem stops growing from an early
stage. This causes the stem to grow upwards and
outwards, away from the original apex (which remains
dead), resulting in the characteristic obconical shape.
• The female cones produce drops of nectar to
entice insects to pollinate them.
• They have a single tap root grows deep into the
sandy desert soil in search of water. The roots of
Welwitschia can grow up to 30 meters deep, sponge
and lateral roots are also a part of the root system.

11. Importance
The leaves that lay on the sand surface also prevent wind
erosion. Antelope and rhino chew the leaves for their juice
during times of drought, and spit out the tough fibres. They
also eat the soft part near the groove. This luckily does not
damage the plant as they simply grow out again from the
meristematic tissue.
The core, especially of the female plant, was used as food
for people in earlier times. It is said to be very tasty either raw
or baked in hot ashes, and this is how it got its Herero name,
onyanga, which means onion of the
desert.

12. Reproductive Structure
The female plant has large cones while the male plant
has flowers. The male reproductive structure has six
stamens each with a anther and a pistil. A female plant of
average size may bear from 60 to 100 or even more cones.
The Welwitschia female plant can produce a lot of seeds:
up to 10 000 or even more. Unlike other known plants
fertilization occur in the pollen tube rather than in the
embryo sac. It is known that wind plays a major role in the
fertilzation, but much has to be learned about a little insect
which also helps with the fertilization.

13. Ephedra
Most species of are branched shrubs (or rarely small trees) while others are
vine-like, often clambering over other vegetation.
They have slender stems with needle like leaves and small, sometimes
brightly colored, cones.
They grow in dry areas in the Northern hemisphere, such as North
Africa, Europe and North America.
Ephedra looks very much like a gigantic version of psilotum and can
grow up to 3m.
Some are monoecious.
Known as jointfirs.

14. Importance
1. @CHINA - known as ma-huang ephedrine colds,
fever, sweating,
Decongestant
2. @Southwestern UNITED STATES and MEXICO
(stem fragments) Mormon tea, Mexican tea, squaw
tea, and desert tea
3. Used for losing weight, obesity, enhances athletic
performance.

15. • Have fruit-like juicy covering for the seeds, which, like fruit,
are edible to birds and aid in the spreading of seed.
• Leaves have network of veins, something seen in
dicotyledonous flowering plants, but no earlier evolved plants.
• All are dioecious, with the male plants producing catkins of
stamens and the females catkins of ovules barely protected
by an envelope. Majority of the species are lianas.
• There are about thirty species in the genus, which occurs
throughout the tropics in Asia, South America and in
Central Africa.
Gnetum

16. Importance
@ Nigeria
the leaf of G. africanum is used in the treatment of an
enlarged spleen, sore throats and as a cathartic
@Ubangi
treatment of nausea and is considered to be an antidote to
some forms of poison
@ Congo-Brazzaville
the leaves are used as a dressing for warts and boils and
a tisane of the cut-up stem is taken to reduce the pain of
childbirth

17. www.phytoimages.siu.edu
Gnetum
G. gnemon
Distribution: Fiji and
Solomon Isls to Malesia,
from Sumba and Sulawesi
through the Philippines to
New Guinea, the Malay
Peninsula,

18. www.phytoimages.siu.edu
Gnetum
G. gnemonoides
Distribution: New Hanover, Peninsular Malaysia, Billiton,
Borneo, Philippines, Sulawesi, Moluccas, New Guinea

19. www.phytoimages.siu.edu
Gnetum
G. latifolium
Distribution: Philippines, New Guinea