Ganonema farinosum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit; 2, tuft of assimilatory filaments with rhizoidas and a 4-celled carpogonium on a medullary cell; 3, mature carposporophyte with involucre of sterile filaments; 4, spermatangial branch.

Ganonema farinosum (J.V. Lamour.) K.C. Fan & Yung C. Wang

Protologue: Acta Phytotax. Sin. 12: 492 (1974).

Family: Liagoraceae

Chromosome number: 2n= unknown

Synonyms

• Liagora farinosa J.V. Lamour. (1816),
• L. cheyneana Harv. (1855).

Vernacular names

• Philippines: baris-baris (Ilokano).

Origin and geographic distribution

G. farinosum is widely distributed in the tropical waters of the Atlantic, Pacific and Indian Oceans. In South-East Asia it has been recorded from Thailand, Vietnam, Malaysia, Indonesia (Irian Jaya) and the Philippines.

Uses

G. farinosum is used as human food and as a source of mucilage. In medicine, G. farinosum is applied as antibacterial agent and has an acetylene-containing fatty acid derivative which strongly inhibits venom PLA₂ of bees.

Production and international trade

No production data are available for G. farinosum. Biomass is obtained from the abundant natural stocks.

Properties

G. farinosum is not much grazed by fish (it is toxic to some of them) and has antimicrobial activity. It contains the toxic acetylene-containing lipids 4-hydroxynona-2E-en-1-a1, octadeca-5-7z-trinoic acid, octadeca-7 hydroxy-5yne-9z,12z-dienoic acid and glyceryloctadeca-5yne-7z,9z,12z-trinoate.

Description

• Thalli soft, lubricous, to about 13 cm tall, pinkish, lightly calcified, farinose, attached by small discoid holdfasts.
• Branching pattern basically dichotomous, with interdichotomal lengths decreasing towards terminal portions of the thallus; branches numerous, terete, about 1.5 mm in diameter, with apices forking into very short, acute, terminal branchlets.
• Assimilatory filaments about 445 μm long, 30 μm broad; cells nearly moniliform throughout; cells of mature medullary filaments broad (more than 40 μm in diameter).
• Life cycle triphasic, diplo-haplontic and heteromorphic.
• Gametophytes dioecious.
• Antheridia borne in capitate clusters at tips of assimilatory filaments.
• Carpogonial branches straight to slightly curved, frequently compound; carposporophyte compact, with terminal carposporangia and little or no post-fertilization fusion of carpogonial branch cells.
• Tetrasporophytes only seen in laboratory culture, forming semicircular cushions (about 5 mm in diameter), Acrochaetium-like, filamentous, heterotrichous, with markedly ramifying creeping systems and sparsely branched erect monosiphonous parts, 14-18 μm wide, carrying scattered wide hairs on apical cells; each cell with stellate chloroplast and large pyrenoid.
• Tetrasporangia and monosporangia in small terminal clusters on erect filaments; tetraspores 14-16 μm in diameter, monospores 20-22 μm in diameter.

Growth and development

Tetraspores of G. farinosum develop into Acrochaetium-like protonemal stages, with shorter and narrower cells than the tetrasporophytes and surrounded by mucilage of firm consistency. These protonemal stages soon grow into the gametophytic macroalgae.

Other botanical information

The genus Ganonema K.C. Fan & Yung C. Wang was originally segregated from Liagora J.V. Lamour. principally on the relationship of the carpogonial branch and its location. Although this does not seem to be a consistent character, other characters are now used to retain this separation.

Ecology

G. farinosum is found attached to rocky substrate among other algae in the subtidal and intertidal areas exposed to air during low tides.

Propagation and planting

G. farinosum is not found in phycoculture.

Harvesting

G. farinosum is harvested by hand-collecting only from natural populations.

Prospects

G. farinosum is likely to continue being used as human food. Its antibacterial, antimicrobial, toxic and venom-inhibiting properties are interesting features for future pharmaceutical utilization.

Literature

• Abbott, I.A., 1984. Two new species of Liagora (Nemaliales, Rhodophyta) and notes on Liagora farinosa Lamouroux. American Journal of Botany 71: 1015-1022.
• Abbott, I.A., 1990. Taxonomic and nomenclatural assessment of the species of Liagora (Rhodophyta, Nemaliales) in the herbarium of Lamouroux. Cryptogamie, Algologie 11: 111-136.
• Huisman, J.M. & Kraft, G.T., 1994. Studies of the Liagoraceae (Rhodophyta) of Western Australia: Gloiotrichus fractalis gen. et sp. nov. and Ganonema helminthaxis sp. nov. European Journal of Phycology 29: 73-95.
• Mayer, A.M.S., Paul, V.J., Fenical, W., Norris, J.N., de Carvalho, M.S. & Jacobs, R.S., 1993. Phospholipase A₂inhibitors from marine algae. Hydrobiologia 260/261: 521-529.
• Von Stosch, H.A., 1965. The sporophyte of Liagora farinosa Lamour. British Phycological Bulletin 2(6): 486-496.

Sources of illustration

Trono, G.C., 1986. Philippine seaweeds. In: Guide to Philippine flora and fauna. Vol. 1. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines. Goodwill Bookstore, Manila, The Philippines. Fig. 72, p. 264 (habit); Womersley, H.B.S., 1994. The marine benthic flora of Southern Australia. Part 3A. Rhodophyta. Flora of Australia, Supplementary Series 1. Australian Biological Resources Study, Canberra, Australia. Fig. 25, p. 95 (details of carpogonium and carposporophyte); Taylor, W.R., 1960. Marine algae of the eastern tropical and subtropical coasts of the Americas. University of Michigan Studies, Scientific Series. University of Michigan Press, Ann Arbor, Michigan, United States. Vol. 21: Plate 45, fig. 2, p. 753 (spermatangial branch). Redrawn and adapted by P. Verheij-Hayes.

Authors

• G.C. Trono Jr