Pro Flowers estimates that there are 25,000 varieties of orchids. Although they are thought of as a tropical flower, they can be grown in a variety of climates. They are beautiful by themselves or as part of a fresh flower arrangement.
History
Historically, orchids were interpreted to mean wealth, beauty, and true love.
Greeks
The ancient Greeks associated orchids with virility. They believed that if a man ate orchid tubers, he would father a boy, while if a woman ate orchid tubers she would conceive a girl, according to Teleflora.
Anniversary
The orchid retains its meaning of true love by being the official flower for the 14th wedding anniversary.
Healing
Aztecs associated the orchid with healing and would drink a mixture of vanilla orchid and chocolate for strength. Chinese believe that the orchid heals lung disease, according to Pro Flowers.
Color
The meaning of orchids also vary with color. For example, pink orchids are said to represent affection, while the cattelya orchid, which has white blossoms ,represents mature charm, according to Teleflora.
Occassions
Because the orchid has such a wide variety of meanings, they are often sent to commemorate many special occasions, such as anniversaries, congratulations and thank yous.
Source: http://www.ehow.com/facts_5745833_meaning-orchid-flowers.html