This group of organisms is characterized as having flagella with mastigonemes that are hollow or "straw-like". Unlike the fungi, all members of the group have mitochondria with tubular cristae and synthesize lysine via the diaminopimelic acid pathway. The stramenopiles (Kingdom Stramenopila) that were previously included in the fungi and that have a way of life like the fungi are the Oomycetes, Hyphochytriomycetes and Labyrinthulomycetes. The so-called heterokont algae are also in this group that includes, among other groups, the diatoms, brown algae and golden brown algae.
The evidence contained in their DNA and manifest in the organization of the kinetosome and related structures clearly establishes their affinities with some of the "algal" groups. How closely related the three fungus-like groups are remains to be established. One of us (MFS) prefers to think that acquisition of photosynthesis occurred more than once and after considerable divergence among the heterotrophic forms. Time and more molecular data will get closer to the truth. Their phylogeny that clearly separates them from the Kingdom Fungi does not, however, prevent their having what we call a fungus way of life and absorptive nutrition.
The organisms in the above tree are called Stramenopiles (sometimes straminipiles). Some of the organisms have nutritional, ecological and morphological features that make for a fungus way of life and one reason they are often studied by mycologists. The above tree is based upon morphological and molecular (unpublished, Lee & Fuller) data.
References:
Bartnicki-Garcia, Salomon. 1996. The hypha: unifying thread of the fungal kingdom. In: A Century of Mycology ( Ed. B. Sutton). British Mycological Society. Cambridge University Press.
Dick, M.W. 1997. Fungi, flagella and phylogeny. Mycological Research 101: 385-394.