About Acetabularia acetabulum (Linnaeus) P.C.Silva, 1952
This species of alga, Acetabularia acetabulum, anchors itself to substrates using rhizoids, which are root-like structures. These rhizoids are the only part of the alga that persists through the winter. Its thallus is made up of a single cell. In spring, a slender vertical stem grows from the rhizoidal holdfast, reaching a length of approximately 5 centimeters (2 inches). Growth pauses at intervals, during which a whorl of dichotomously branching hairs forms around the stem. As the stem lengthens and additional whorls develop, older lower hairs fall off, leaving circular scars behind. Once the stem is fully grown, a disc-shaped cap that can be up to 1.2 centimeters (0.5 inches) wide develops at the stem's tip. The entire frond takes on the appearance of a pale green parasol, and additional whorls of hairs grow from the upper surface of the cap.
