ABSTRACT
The genus Rubus, in the Rosaceae family, comprises a large number of highly variable and heterogeneous species, occurring throughout the world except in desert regions, but most numerous in the northern hemisphere. The most important members of the genus Rubus are the red raspberry species, which are important cultivated crops in many parts of the world, particularly in Europe and North America. Individual species of Rubus vary greatly in form and structure of the inflorescence. Most Rubus species produce hermaphroditic flowers, although many are self-sterile and a few are functionally dioecious. The process of flower bud formation is essentially the same in all species of Rubus. The time of flower bud initiation in most forms of Rubus is believed triggered by shortening daylengths and lowering temperatures. Flower initiation in most normally biennial-fruiting Rubus occurs after the cessation of terminal growth in the fall.
