Question
Some orchids have flowers that stem from the top of the pseudobulbs (eg. Encyclia). Other have the flowers on spikes that come from the base of the bulbs. Can you tell me which orchids belong to one or the other group?

Answer
Jose, as you are aware, there are thousands of orchid genera, so I will note just a few of the most common types.  Cattleya alliance species and hybrids generally flower from the top of pseudobulbs.  Encyclias are a mixed bag but most flower from the base. The cool growing dendrobiums form their flowers along the upright canes while the warm grow dendrobiums flower from the top of canes. Oncidium alliance plants, for the most part, flower from the base of the pseudobulb. Interestingly, plants carry a potential to break the mold.  Brassavolas which, almost without exception, flower from a leaf axil, may occassionally flower from the base of the plant. If you have other genera in mind, feel free to let me know which ones interest you that I have not addressed here.