AGAR AND RELATED PHYCOCOLLOIDS 



73 



substratum. This phase of G. confervoides is widely distributed in North Carohna 

 and in temperate oceans throughout the world. In North Carolina, however, the 

 attached, sporulating phase does not occur in sufficient abundance to be eco- 

 nomically valuable, as it does in Australia and South Africa. The other phase is 

 a loose, drifting, nonspore-forming plant that is not attached at any stage of its 



Fig. 5-12. Gracilaria foliifera, the principal agar source in 

 Florida, and an important source in North Carolina. 



life history. It lies loose in shallow, quiet water, or drifts about as it grows. Re- 

 production is purely a matter of growth and accidental breaking apart of the 

 plant, with continued growth of the fragments. In the fall plants of this phase 

 accumulate in great masses in areas where tidal currents are not strong enough 

 to sweep them out. At times the drifts may be 1 to 3 feet deep in water hardly 

 deeper at low tide than the seaweed. As the water temperature falls to about 

 60° F (15.6° C), growth ceases and all plants in areas where waves and currents 

 do not move them, gradually settle down, become semidormant, decay in part, 

 and break into small pieces during the winter. In the spring (usually April) when 

 water temperatures again become favorable for growth, all fragments that are 

 still alive begin to sprout and soon become bushy and semibuoyant. In June some 

 of the plants begin to drift and, as they become larger, are broken into small 

 pieces. By July this purely vegetative phase is again widely distributed and has 

 begim to accumulate in masses. Commercial collecting usually begins in August 

 and reaches a peak in October. Although it would appear that the loose, drifting 

 phase is derived annually from attached, spore-forming plants, there is no 

 evidence that this occurs in North Carolina. 



