The stages of bean seed growth are vegetative (V), with a number of stages corresponding to the number of leaves, and reproductive (R), with eight stages culminating in full maturity of the bean pods. The names and nature of stages are specified by The Iowa State University staging system.
As a bean seed develops into a bean plant, it goes through two main phases: vegetative and reproductive. Inside a bean seed there are two cotyledons, which are units for storing food. Within them is one embryonic bean plant that consists of embryonic leaves, epicotyl and an embryonic root, hypocotyl.
- VE: Emergence of the bean plant, 1 to 2 weeks after planting - the primary root grows out of the bean seed that has absorbed half of its weight in water. Cotydelons are pulled up and emerge from the soil.
- VC: Unrolling of unifoliolate leaves, 7 to 10 days after VE - the epicotyl grows above the cotyledonary node and the first leaves unfold.
- V1, V2 to Vn: unrolling of trifoliolate leaves, each stage occurring every 5 days - with each stage, another trifoliolate leaf unrolls and another node appears. N is the final number of leaves.
- R1 to R8: the reproductive growth stages of the bean plant - during stages R1 and R2, flowers emerge and go into full bloom. R3 and R4 see the development of pods. During R4 and R5 the new seeds grow, and are fully developed by R6. R7 and R8 are the two steps to the bean plant's full maturity.