Taxonomy of Orchids
 

Identifying an orchid by its genus, species or floral formula is pure Botany.
Pardon my ignorance, how much a technical classification influences day to day care of the plants?
A Dendrobium is Dendrobium or Phalaenopsis is Phalaenopsis or others like wise.These guys carry the typical characteristics of their groups or genera,once you get the hang of it each of these have same pluses and minuses in maintenance on daily/ regular basis.
What I mean is by delving in to a subclasses of an orchid how is going to matter? In regular care.
A Vanda doesn’t like medium period . Will it help to go in to sub classification of a Vanda?

Most genera contain species from different elevations,latitudes, etc.Orchids come from every continent except Antarctica, from sea level to above treeline, from the tropics to the Arctic.Clearly the orchids from these different environments have different needs. Most Phalaenopsis have similar cultural needs, but that's just about the only genus for which the general advice holds. Dendrobium is a huge genus, divided into several sections. And even within the sections there is much variation because they come from different elevations, different habitats. Some grow warm, some cool. Some need a dry winter rest, others don't. I could go on and on about the other genera, but the same holds, One really must know the details - the species, or in the case of hybrids, the parentage.

Roberta is dead on - there are all sorts of cultural requirement variations within a genus (especially within large genera), and even within a single species, where different populations may have grown under different conditions.

Thank you Ray, Thank you Roberta

I agree with Roberta and Ray. I guess I would even take issue with Phalaenopsis being homogeneous. Once you get into species, they don't all seem to thrive under the same treatment, especially now that the genus includes species like Phalaenopsis japonica (formerly Sedirea). Even among closely related species and hybrids, species identity and species mix in the hybrids can make a huge difference in terms of factors like temperature tolerance.

At least Sedirea japonica can grow on the warm side, although it does't have to. Point well taken, even the generalities that are at least moderately close to valid, have exceptions. Just emphasizes the point that culture information at the genus level is very unlikely to be useful for understanding the needs of a particular plant.