orchid - problem solving

We have 3 orchids - completely dissimilar - which we refer to as envelope orchids. What appears to be a new shoot appears and develops into a flat envelope about 3"long, the single flower stem appears out of the envelope.  Can you tell me the name of this orchid type.  We have one that has very bright light purple flowers; one that has quite short leaves and small white flowers like a small cluster of spears each about 1"long with the stamens(?) at the end; and a third which has a 4" flattish flower much more like a 'traditional' orchid flower, with 6 separate parts, 5 petals: 3 forming the top half, two  the bottom half and all pink and a much darker and bigger central bottom part which is deep magenta with the stamens etc. in it. 

Sadly I have no photos. at the moment.