Scinaia hormoides (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit of a cystocarpic plant; 2, section of the outer part of a thallus, with utricles, hypodermis, medulla and groups of small coloured cells between the utricles; 3, surface view of utricles and small groups of small coloured cells; 4, section of the outer part of a thallus, with utricles, hypodermis and medulla; 5, section of a fertile male thallus with hemispherical clusters of spermatangia.

Scinaia hormoides Setch.

Protologue: Univ. Calif. Publ. Bot. 6: 106, 125, pl. 12: figs 33-35, pl. 13: figs 36, 37 (1914).

Family: Galaxauraceae

Chromosome number: 2n= unknown

Vernacular names

• Philippines: garganatis (Ilokano, Visayan).

Origin and geographic distribution

S. hormoides was originally recorded from Haleiwa, Oahu, Hawaiian Islands and is also represented in South-East Asia (Malaysia, Indonesia, the Philippines and the northern coast of Papua New Guinea). In the Pacific Ocean it is also known to occur in Japan and in Polynesia.

Uses

S. hormoides as human food obtained from natural stocks is used. It is prepared as seaweed salad mixed with onions and tomatoes and dressed with sweet-sour sauces. It is also a good source of agar, but is not used commercially.

Production and international trade

S. hormoides is not cultured and supply is gathered from natural stocks.

Properties

Scinaia Bivona contains floridoside and floridean starch which are its principal carbohydrates. Mannoglycerate is also present in small quantities. Cellulose is the principal component of the cell wall. Fucosterol and sitosterol are also present.

Description

• Thalli up to 7 cm tall, bright red-greenish purple, attached to substrate by discoid holdfast; stipe short, not constricted, hard in texture; frond regularly dichotomously branched.
• Branches uniformly moniliform, composed of globular, subglobular or oblong segments, with longest segment up to 7 mm × about 5 mm.
• Cross-section of branch with epidermal tissues of generally colourless hexagonal to octagonal cells (utricles) on the surface, about 20 μm in diameter, mixed with few, grouped, small coloured cells; hypodermis with reddish-purple, globular or ovoid assimilatory cells.
• Medulla consisting of long colourless branched filaments.
• Life cycle probably triphasic, diplo-haplontic and heteromorphic.
• Tetrasporophytes probably microscopic, filamentous, branched, producing cruciately divided tetrasporangia. Gametophytes dioecious.
• Spermatangial stands with long, narrow spermatangial mother cells, penetrating between utricles, producing small, 4-5 times divided branches, forming hemispherical clusters of spermatangia, 250-350 μm in diameter, covering surface of male plants.
• Cystocarps broadly pyriform or globular, with ostiole sunken in thallus, scattered especially in middle portion of branches, surrounded by pericarp of 3-7 layers, with numerous slender gonimoblasts and carpospores released to central cavity.

Ecology

S. hormoides grows attached by a well-developed holdfast to solid substrates like rocks, pieces of dead corals, shells and on crevices of reef crest as well as in shallow subtidal areas characterized by clear water and moderate water movement.

Propagation and planting

No phycoculture of S. hormoides is known.

Harvesting

S. hormoides is only hand-collected from natural stands for direct local use.

Handling after harvest

S. hormoides is sold and used fresh and/or sun-dried.

Prospects

S. hormoides is suitable as edible decoration in appetizing salads.

Literature

• Setchell, W.A., 1914. The Scinaia assemblage. University of California Publications in Botany 6(5): 79-152, pls 10-16.
• Tazawa, N., 1975. A study of the male reproductive organ of the Florideae from Japan and its vicinity. Scientific Papers of the Institute of Algological Research, Faculty of Science, Hokkaido University 6(2): 95-179, pls 1-10.

Sources of illustration

Setchell, W.A., 1914. The Scinaia assemblage. University of California Publications in Botany 6(5): Plate 12, figs. 34 & 35, p. 145 (sections outer part thallus), Plate 13, fig. 37, p. 147 (surface view thallus); Tazawa, N., 1975. A study of the male reproductive organ of the Florideae from Japan and its vicinity. Scientific Papers of the Institute of Algological Research, Faculty of Science, Hokkaido University 6(2): Fig. 5 C, p. 102 (spermatangia); 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. 73, p. 264 (habit). Redrawn and adapted by P. Verheij-Hayes.

Authors

• G.C. Trono Jr