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PHYCOLOGICAL SOCIETY OF AMERICA
Gracilariopsis gametophytes
The gametophytes of Gracilariopsis lemaneiformis are difficult to identify unless the female is covered with dark red bulbous protrusions that are the developing carposporophytes. In the photograph below, the red bump is a well-developed carposporophyte, and the white bumps are individuals of the parasitic alga Gracilariophila oryzoides.
On the surface of male plants, cells called spermatangial parent cells each divide to produce one spermatangium. The spermatangial parent cells are produced in pairs and sit on a smaller basal cell. The end result is a rabbit head, with the long oval ears being the parent cells and the small rounder head being the basal cell. During my sectioning of oodles of algae, I never found a structure that I was convinced was male a reproductive bit.
The female reproductive structures (before fertilization) also lie in the outer layers of cells (the cortex). A long, hair-like protrusion called the trichogyne sticks out from the plant, ready to snag any sperm that touch it. The trichogyne is an extension of the caropogonium, which is the cell containing the egg nucleus. As luck would have it, the carpogonium is the last cell on the carpogonial branch. In G. lemaneiformis the carpogonial branch is three cells long, and is nestled between two other branches called the sterile branches. The base of the carpogonial branch is the supporting cell. To find out what madcap adventures these cells have after fertilization, check out the carposporophytes.
--Ben Hale 1999.
