This is an internet search that led here.
First, let’s remind what should be obvious but is apparently not realised by many people: since plants in general both have stamens and pistil(s), they are hermaphroditic. Of course, there are great variations with regard to realised gender in plant species, though, please go here for a short overview, but the most common situation is still hermaphroditism.
Orchids, as wonderful plants they can be, just follow this majority rule. One cannot be completely outstanding I guess. Indeed, as curious as it seems, orchids fairly rarely depart from possessing both male and female attributes at the same time, even if they indulge to quite strange sexual fantasies.
So the answer is straightforward: you don’t need to wonder if an orchid is male or female. There are good odds that they are both. And they are perfectly happy with this.
Catasetum macrocarpum, female flower (Courtesy of Russian in Brazil).
The only exception I know in orchids so far is a strange and exciting genus, Catasetum (follow next link for a quite nice pixes collection).
Catasetum orchids are dioecious, that is, evolved into full female or full male individuals from their hermaphroditic ancestors. This evolution path is quite frequent and occured many times independantly in plants, mostly as a way to avoid negative effects of selfing and inbreeding. But such negative effects are required for evolving the full separation of sexes. Not every species endures inbreeding depression nevertheless, and that’s probably why so many plants are still hermaphroditic and without making any issue about it. Many others have found their way to prevent selfing, dioecy being only one of them.
The trick is that once you evolved such a clear cut divide between maleness and femaleness, you must have some special agents willing to transport pollen to a safe place. Catasetum are pollinated by wonderful shiny bees, Euglossines, which pollinate a wide range of exotic plants in tropics.
And since I found a quite nice movie, I shall let you see it. That’s a male (oops, female) Catasetumbeing visited by marvellous greeny petsies:
Euglossine bees pollinating Catasetum macrocarpum
Originally uploaded by Russian in Brazil
Seeds Aside 
[…] protection in plants: More plant sunburns protection…. Then it was back to orchids with How to tell orchid males from females? which includes a neat movie of bees pollinating plants from the one genus of orchids that actually […]
This article is somewhat in error.
Catasetum is not dioecious in the classical sense. That is to say, there are not male and female individuals — plants which produce only staminate or pistillate flowers.
Each individual may produce male or female flowers depending on the conditions in which it is grown, and those in conditions that are borderline between the two states may actually produce both male and female flowers.
That’s just environmental sex determination, and it doesn’t contradict the sexual categorization, except that some individuals may be monoecious in borderline conditions. But that’s still dioecy on average.
Think of a well known other environmental sex determinism in turtles. You wouldn’t say turtltes are not sexual in the classical sense. Even if sex results from temperature conditions during development. Some fish species do change their sex too, and these species are still considered bisexual…
The situation is just the same here, turtles won’t change sex the next year though. But sex is there, and it’s either male or female.
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