Abstract
SUMMARY: Germinating zygotes of Himanthalia elongata (L.) S. F. Gray have a prolonged stage free from rhizoids. The spherical zygote flattens when settling on a substratum and a rim‐like structure develops at the periphery of the flattened base. Numerous rhizoids appear simultaneously 5–7 days after fertilization. The possible significance of the germling's shape and structure in relation to attachment is discussed.