What is septa and what is difference between septate and aseptate in anatomy of flowering plants

Fungal hyphae which do not have crosswall is called septata.

*Septate and aseptate
Xylem is a vascular tissue responsible for conduction of water. It is a complex permanent tissue. Xylem comprises of cells of four types namely, vessels, tracheids, xylem parenchyma and xylem fibres.

Xylem fibres are sclerenchymatous fibres which are dead cells. These cells have thickened cell walls.
Xylem fibres are either septate or aseptate.

Xylem fibres are either divided along their length with some partitions. These partitions make them septate. You can observe the divisions in the central lumen of septate xylem fibre.
If the xylem fibre is not divided by any partitions projecting inside the lumen, it is termed to be aseptate.