Description:  Throughout the world, more than 17,000 species are known, and varieties vary in size and shape.  Oncidium blossoms are ½ to 1 inch and are usually yellow with orange-red markings.  Cattleya blossoms are large, ruffled and usually 5 to 6 inches across in white or purple with contrasting throats.  Phalaenopsis have moth- or butterfly-shaped flowers in colors such as white, pink, purple and bicolors.  Cymbidium and dendrobium flowers have a butterfly-like shape and are 3 to 4 inches acress.  The larger of the two, cymbidiums are white, yellow, green or lavender with pink or red lips, while dendrobiums are often white or lavender.