| Phalaenanthe Dendrobiums have a raceme, which indicates a simple inflorescence with opposite alternating flowers on individual stalks (pedicels) and no terminal flower (the terminus of the inflorescence is actually a dormant meristem in Dendrobium). Other common inflorescence types in orchids are umbels (simple pedicellate inflorescence with all flowers at apical end arising from one point), panicles (usually racemose panicles; compound, branching (e.g. Oncidium)), and solitary flowers.
Anton is correct. True spikes are not common at all in orchids. Even things that LOOK like spikes are usually just spicate racemes, or something. The difference is that true spikes have flowers that are sessile to the peduncle, whereas orchids have pedicels (individual stalks for each flower on an inflorescence).
-Cj |