Pictured above is the sporophyte stage of Macrocystis pyrifera. When most people think of giant kelp, the sporophyte stage is what most recollect. This is not surprising, considering the gametophyte stages are microscopic. It is this life history stage that has the largest impact on kelp forest ecology. At the base of the kelp are reproductive blades that produce thousands of spores, located in sporangia structures.
Pictured below are sporangia structures Macrocystis pyrifera, as well as other Laminariales: Alaria, and Laminaria farlowii. The sporangia are the dark circles, contained within the oblong structures. Each sporangia produces many kidney-shaped motile heterokont spores.
Copyright 2001: James
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