3. ORCHID FAMILY (ORCHIDACEAE)
Largest
family of flowering plants
Terrestrial, epiphytic, or
saprophytic herbs
Orchid flowers come in different
colours except black
Example of an orchid is Vanilla
planifolia, native to Mexico and
Central America
4. Habitat & Distribution
Second
most widely distributed plants in the
world after grasses
Mainly found in warm, moist places
Also found in dry or seasonally cold
environments such as savannahs and semideserts
Found in rainforests, swamps
Worldwide (except Antarctica): mostly
tropics in countries such as Guyana,
Venezuela and Brazil; even the Arctic Circle
and Africa
7. Characteristics of Orchids:
Distinguishing characteristics of the orchid are
found in the flower.
•
The petal aka lip or labellum is opposite the
fertile stamen.
•
The fertile stamen or stamens are on one
side of the flower opposite the lip, making
the flower bilaterally symmetrical.
•
The pistil is in the middle of the flower.
•
Single anther is retained at the top of the
column to form a cap-like structure (in most
orchids).
8.
9. Characteristics of Orchids (con’t):
Reduced
filaments, anthers, style and stigma; fused
into one structure called the column
10. Characteristics of Orchids (con’t):
Stigma is in the form of a shallow
depression on the inner sides of
the column.
In the bud, the lip is oriented
upward but as the flower matures,
it usually ends up downward;
process called resupination.
Outer whorl: 3 sepals
Inner whorl: 3 petals
11.
12. Characteristics of Orchids (con’t):
Rostellum
(flap of tissue covered with sticky
stigmatic liquid) separates the stigma and
anther.
Primitive orchids – pollinia (contains many
pollen) stick to stigmatic fluid on the insects’
backs because the orchids contain no
rostellum.
Advanced orchids – pollinia caudicles are
already attached to the rostellum; a portion
comes off as a sticky pad known as the
viscidium
13.
14. Characteristics of Orchids (con’t):
Fruits
are dry capsules; small, numerous, dust-like
seeds that lack an endosperm (wind dispersal)
The seeds depend on fungus since the fungus
penetrates the seed and provides it with nutrients
to germinate and grow.
Orchids contain several types of nectaries,
including the extrafloral types. Floral fragrances are
diverse, from quite sweet to the smell of rotting liver.
Some nectaries are located on the side lobes of
the lip and secretion along the groove of the lip
occurs.
15. Economic Importance of
Orchids
They
are used mainly as ornamentals (to
beautify the environment).
Their sweet extracts can be used in
perfume production.
Orchids are used as food in Indonesia.
Orchids have medicinal value in China
and Japan.
Several species of orchids are used as a
glue substitute (derived from the
pseudobulbs).
16.
17.
18. References:
Raskoti,
B. B.; 2013; Orchid Distribution;
http://www.ionopsis.com/distribution.htm;
22/09/2013
Welch-Keesey, M.; 2013; Just the Facts about
Orchids;
http://www.indyzoo.com/SiteAssets/pdfs/Handou
tA-OrchidFacts.pdf; 22/09/2013
