Life History and Reproduction of Furcellaria fastigiata (L.) Lam: With two Plates and two Figures in the Text

Biology of Furcellaria lumbricalis (Hudson) Lamouroux (Rhodophyta: Gigartinales), a commercial carrageenophyte

“…Early development of thalli from carpospores and tetraspores is essentially the same, and has been described in detail by Rosenvinge (1917), Austin (1960c) and Bird (1977). Spores attach firmly to the substratum over a period of two days or longer, and germination usually begins within five days, with the formation of an oblique cross wall.…”

“…The gametangial and tetrasporangial generations are isomorphic, although there is a tendency for male thalli to be slightly smaller and more densely branched than females and tetrasporophytes, and the latter to be the tallest of the three phases (Austin, 1960d). Except for a single reported instance of monoecism (Austin, 1960b), the haploid phase is dioecious. Male and female plants usually occur in equal proportions in a population, but tend to be outnumbered by tetrasporophytes.…”

“…Male and female plants usually occur in equal proportions in a population, but tend to be outnumbered by tetrasporophytes. There are no reports of gametangia and tetrasporangia on the same thallus (Austin, 1960b). Reproductive structures are formed in the branch tips, which are shed after release of spermatia or spores.…”

“…A gelatinous cuticle over the spermatangia imparts a mucilaginous texture to the tissue. Welldeveloped male thalli are characteristically compact and bushy (Grubb, 1925;Austin, 1960d), which Austin (1960b) ascribed to their tendency to retain spermatangial apices until well into the season of maximum vegetative growth (see Phenology), so that less regeneration occurs before fertility resumes. Alternatively, it has been suggested (Austin, 1960d) that male plants may become fertile more than once per year, thereby further limiting their vegetative growth.…”

“…Carposporophytes develop inwardly within the apices and at maturity are compact masses that may attain a diameter one-third that of the enlarged fertile apex. About 150 may be produced by a single fertile ramulus (Austin, 1960b). In tetrasporophytes, elliptical, zonately divided sporangia lie scattered within the apical cortex.…”