Articles

Gracilaria blodgettii Harv.

Gracilaria blodgettii Harv.

Family

Gracilariaceae

Synonyms

Gracilaria cylindrica Børgesen.

Vernacular Names

Indonesia Agar-agar gros, agar-agar biru, sango sango (Sulawesi).

Geographical Distributions

Gracilaria blodgettii is found along the tropical and subtropical coasts of the Atlantic Ocean (Caribbean, Florida), the Indian Ocean (Aldabra Islands, Seychelles, Mauritius, India, Sri Lanka, Andaman Islands, Australia) and the Pacific Ocean (China, Japan, Taiwan). In Southeast Asia, it has been recorded in Vietnam, Peninsular Malaysia, Singapore, Indonesia, the Philippines and Papua New Guinea. The type locality is Key West, Florida (United States).

Description

Gracilaria blodgettii is a plant up to 10 cm tall. It has single thalli, which is erect, attached to the substrate by a discoid holdfast and with cylindrical branches that reach a width of up to 2 mm. The branching pattern is variable. It ranges from frequently dense to sparse and from irregularly alternate to a tendency of becoming second. The third and higher-order branches are often beset with short branchlets and measuring 3 mm x 1 mm. The branchlets are spindle-shaped or obtuse. According to some descriptions, the branch bases are distinctly constricted.

The plant in transverse section is composed of two rows of small cortical cells which are inwardly followed by 2-3 layers of medium-sized cells. The medulla consists of large cells which are nearly uniform cylindrical to oval, and very thick-walled (to 26 µm thick). Spermatangia is organised into shallow Textorii-type spermatangial sori. The cystocarps are hemispherical to spherical and not constricted at the base. Transverse section through mature cystocarps with sterile gonimoblast bears tubular nutritive cells that reach a well-developed pericarp of 10-15 layers of cells.

Ecology / Cultivation

Plants of Gracilaria blodgettii are found in tide pools or in shallow subtidal areas, attached to rocks, pieces of shells or coral fragments. In Vietnam, it is found abundantly from October to July. It is commonly cultivated in brackish water swamps along coastal areas of Hai Phong and Cat Hai Island.

Line Drawing / Photograph

Gracilaria_blodgettii

References

  1. Plant Resources of South-East Asia No.15(1): Cryptogams: Algae.