Giant kelp stipes are similar to stems of terrestrial plants. The essential sugars produced in photosynthesis are used to fuel their own metabolic needs, as well as transport them to other parts of the alga, including the holdfast, spore producing blades, and new fronds.
Above is a stained longitudinal section of a giant kelp stipe taken at 4X magnification. Below is a cross section of a giant kelp stipe taken at 4X as well. The darker stained, central regions of these slides are the sieve tubes. These sieve tubes are the tissue responsible for transport of sugars throughout the alga (Bold 1978).
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