Not every relation is a function. But every function is a relation. Function is just a part of relation.
The cubic function.
Range
A formula or graph are two ways to describe a math function. How a math function is described depends on the domain of the function or the complexity of the function.
The Mandelbrot graph is generated iteratively and so is a function of a function of a function ... and in that sense it is a composite function.
a cluster of sporangia is a sorus.
gametophyte
sori
on the underside of a fern frond
Along the base of the shaft
Sorus, plural sori develop in almost all terestrial ferns in aquatic ferns sporocarp is formed in place of sorus to protect the developing spores from water.
Sorus
under the cap
Sori (singular Sorus)
Sporangia
In ferns, a sorus is a cluster of sporangia on the edge or underside of a fertile frond.
it has 8 structures the sorus, blade, pinna, petiole, fiddle head, adventitious roots, frond and rhizome,