Final answer:
A hypha with no cross walls is called a coenocytic hypha. These coenocytic hyphae are found in certain fungi, like bread molds, and feature a continuous cytoplasm with many nuclei.
Step-by-step explanation:
If a hypha has no cross walls, it is referred to as coenocytic. Coenocytic hyphae are characteristic of some fungi, notably within the Phylum Zygomycota, such as bread molds. These hyphae are multinucleate large cells that lack septae, which are the divisions typically found in the hyphae of other fungi.
Most fungi produce septate hyphae, which have internal walls called septa that divide the hypha into cells. These septa often have small pores that permit the flow of organelles and molecules between cells, aiding in the distribution of nutrients and enabling the overall function of the fungus. In contrast, coenocytic hyphae form a continuous cytoplasmic mass without such separation, allowing for many nuclei to exist within a single cell.