http://irrecenvhort.ifas.ufl.edu/plant-prop-glossary/03-gene...Quote; ***juvenile phase*** is defined as a physiological age where the plant can not flower even though the environmental conditions are suitable for flower induction.
English ivy (Hedera helix) dramatically shows this phase change by having a different leaf shape and growth habit in the ***juvenile*** and mature phase.
Plants in the juvenile phase tend to produce cuttings that are easier to root from cuttings.
(((I guess , also called the Vegetive stage, Vegetive meaning easy to grow from a twig etc )))