This is owing to the elongating region (in which proto.
The root hairs grow out from the cells of the piliferous layer immediately behind the elongating tegion.
The apex in this case will describe a circle, or rather a spiral, as it is elongating all the time, pointing to all points of the compass in succession.
There are two distinct types of inflorescence - one in which the flowers arise as lateral shoots from a primary axis, which goes on elongating, and the lateral shoots never exceed in their development the length of the primary axis beyond their point of origin.
Amongst indefinite forms the simplest occurs when a lateral shoot produced in the axil of a large single foliage leaf of the plant ends in a single flower, the axis of the plant elongating beyond, as in Veronica hederifolia, Vinca minor and Lysimachia nemorum.