basipetalous

Basipetalous refers to a type of phyllotaxy or a pattern of development where the youngest parts are located at the base and the oldest parts are at the apex. This is in contrast to acropetalous development, where the youngest parts are at the apex and the oldest parts are at the base.

In the context of leaf arrangement, basipetalous phyllotaxy is uncommon. Typically, leaves are arranged either alternately or oppositely along a stem. However, in certain cases, like the development of compound leaves where leaflets unfurl sequentially, the order can be described as basipetalous if the first leaflets to open are closer to the stem and subsequent ones further out. More commonly, the term is applied to developmental patterns in floral structures or inflorescences.

For instance, in some cymose inflorescences, the main axis terminates in a flower, and further branching occurs below this terminal flower. If the branches that develop first are those closer to the base of the main axis, and subsequent branches develop towards the apex, this can be considered a basipetalous sequence of flowering. Similarly, in the development of certain plant organs, basipetalous growth means that the growth and maturation proceed from the base towards the tip. This contrasts with acropetalous growth, where development proceeds from the tip downwards. Understanding this directional growth is important in studying plant morphology and development.