Table 3 Utility of 10 seagrass species, including habitat and etymology of 50 ethnotaxa.

Cymodocea rotundata Asch. & Schweinf.

Purely marine; shallow regions of tidal and subtidal zones; sandy and muddy substratum

Id: Rhizome creeping, branched, white to pale brown; shoots erect; sheaths pale white; stems less sweet but more salty; leaves straight and slightly falcate; lamina width narrow.

Etymology:$(10) Alai vaari: Alai means waves, vaari means drifted or taking away; used together, Alai vaari means leaves floating along the wave.$(11) Kadal korai: Kadal means sea, korai means$sedge.$(12) Kadal karumbu: means sea sugar cane.$(13) Kadal thazahi pasi: Kadal means sea, thazahi means leafy, pasi refers to thalloid form.$(14) Vellai kadal korrai pasi: Vellai means white, kadal means sea, korrai means sedge, pasi means thalloid form of a seawater alga.$(9) Vellai thazahi pasi: Vellai means white, thazahi means Pandanus leaf type, pasi means thalloid form of a seawater alga.

Utility: Branches and leaves used as feed for goats and pigs. Paste from leaves used to treat wounds. Collected biomass used as green manure for gardens.

Cymodocea serrulata (R.Br.) Asch. & Magnus

Purely marine; deep shallow regions of tidal and subtidal zones; sandy and muddy substratum

Id: Rhizomes creeping, branched; stems reddish brown to white; shoots long, more sweet and less salty, juicy; leaves falcate; lamina broad.

Etymology:$(15) Karumbu: means sugar cane.$(16) Karumbu pasi: Karumbu means sugarcane thalloid, pasi means thalloid form of a seawater alga.$(17) Kadal karumbu: Kadal means sea, karumbu means sugarcane.$(18) Peria korai pasi: Peria means big, korai means sedge, pasi means thalloid.$(19)Peria thazai pasi: Peria means big, thazai means Pandanus leaf type, pasi means thalloid.

Utility: Branches and leaves used as feed for goats and pigs. Paste from leaves used to treat wounds. Collected biomass used as green manure for gardens.

Enhalus acoroides (L.f.) Royle

Pure marine; shallow water; sandy to fine mud substratum

Id: Leaves long, dark green, ribbon-like; rhizome very thick; roots stout; female inflorescence on long peduncles, single flowered like a lily.

Etymology:$(1) Olai pasi: Olai means palm leaf, pasi means thalloid form of a seawater alga.$(2) Vaata alai: Vaataa means running toward the wave, alai means waves; together name means the direction the leaves float along the waves.$(3) Alai vaari: Alai means waves, vaari means floating away; together name means leaves that float along the wave.$(4) Kadal vaari: Kadal means sea, vaari means floating away; together name means leaves swaying in the wave.$(5) Thittu pasi: thittu means patches, pasi means thalloid form of a seawater alga.

Utility: Rhizome and root juices consumed raw to treat seasickness. Rhizome (peeled of skin) consumed fresh with cup of seawater to treat heart conditions and low blood pressure. Rhizomes consumed fresh to ease indigestion and hangover. Paste of fresh leaves used to treat many kinds of skin diseases. Seeds, which taste like almonds, are eaten by people or fed to goats and sheep.

Halodule pinifolia (Miki) Hartog

Tidal and subtidal zones; fine sandy and muddy bottoms; mangrove creeks and swamps

Id: Rhizomes creeping, white to pale brown; shoots long, erect; leave flat, long.

Etymology:$(34) Nedung korai: Nedung means long, korai refers to sedge.$(35) Neettu korai: Neettu means long, korai means sedge.$(36) Korai: Korai means sedge.$(37) Kadal korai: Kadal means sea, korai means sedge.$(38) Kadal korai pasi: Kadal means sea, korai means sedge, pasi means thalloid form of a seawater alga.$(33) Arugampul pasi: Arugampul refers to the terrestrial plant called Cynodon dacylon, which is traditionally called Arugampul; pasi means thalloid form of a seawater alga.$(39) Peria eekku thazhai: Peria means long/big, eekku means sharp tiny stick (like tooth pick), thazhai refers to terrestrial plant of the Pandanus genus.

Utility: Stems are washed and used as goat feed.

Halodule uninervis (Forssk.) Boiss.

Purely marine; deeper tidal and subtidal zones in muddy bottoms

Id: Rhizomes creeping, white to pale brown; shoots short, erect; leave flat, narrow, short;

Etymology:$(41) Kothu korai: Kothu means forms in patches, korai means sedge.$(42) Kattai korai: Kattai refers to stout-strong stem, korai means sedge.$(43) Pullu korai: Pullu means grass, korai means grassy sedge.$(44) Korai: Korai means sedge.$(45) Sinna eekku thazahi: Sinna means small, eekku refers to a sharp tiny stick, thazhai refers to terrestrial plant of the Pandanus genus.$(40) Panjipul pasi: Panjipul means the whole plant is soft to the touch, and tiny; pasi means thalloid form or seaweed.

Utility: Stems are washed and used as goat feed.

Halophila ovalis (R.Br.) Hook.f.

Tidal and subtidal zones; coral debris and muddy substratum

Id: Rhizome creeping, branched, slender, semi-transparent, fleshy, brittle; lamina oblong-elliptic, pale to dark green.

Etymology:$(25) Kadal sedi pasi: Kadal means sea, sedi means herb, pasi means thalloid form or seaweed; together the name means flat seaweed.$(26) Kouthu pasi: Kouthu means bunch, pasi means thalloid form or seaweed.$(23) Murungai pasi: Murungai refers to Moringa plant, pasi means thalloid form or seaweed$(28) Sedi pasi: Sedi means herb, pasi means thalloid form or seaweed.$(24) Seathu pasi: Seathu means mud, pasi means thalloid form or seaweed.$(27) Kadal pasi: Kadal means sea, pasi means thalloid form or seaweed; together name means seaweed.

Utility: A handful of leaves is toasted with three drops of sesame oil and consumed for three days to treat iron deficiency. A leaf paste is mixed with turmeric and applied to cure various skin ailments, including burns and boils.

Halophila gaudichaudii J.Kuo (syn. Halophila ovata Gaud.)

Low tide, wave-less open sea; coarse sandy and soft muddy bottoms

Id: Rhizome slender, terete, fleshy, unbranched, semi-transparent; leaves oblong - elliptic, linear-oblong.

Etymology:$(31) Sedi pasi: Sedi means herb, pasi means thalloid form or seaweed; together the name means herb type pasi.$(32) Elai pasi: Elai means leaf, pasi means thalloid form or seaweed; name means leaf-like structure found in sea.$(29) Poduthali: Poduthali refers to Phyla nodiflora, the leaf of which is is brittle.$(30) Pottal pasi: Pottal refers to the plain sandy substratum where this plant is found, pasi means thalloid form or seaweed.

Utility: A handful of leaves is toasted with three drops of sesame oil and consumed for three days to treat iron deficiency. A leaf paste is mixed with turmeric and applied to cure various skin ailments, including burns and boils.

Halophila stipulacea (Forssk.) Asch.

Id: Herbaceous and creeping; runner slender, transparent, brittle; lamina lanceolate; pedicle short.

Etymology:$Minni pasi: Minnal means lightning, pasi means thalloid form or seaweed; name refers to the reflective light and color of water.$Kadal pasi Kadal means sea, pasi means thalloid form or seaweed; a thalloid looking seaweed.$ Sedi pasi: Sedi means terrestrial seaweed, pasi means thalloid form or seaweed.

Syringodium isoetifolium (Asch.) Dandy

Purely marine; occur in deeper zones on coral flats; sandy to muddy bottoms

Id: Rhizomes creeping, slender, semi-fleshy, white to pale yellow; shoots long; leaves long, lamina terete, succulent/fleshy and thick.

Etymology:$(46) Neer pasi: Neer refers to the watery substance that comes out of the succulent leaves when squeezed, pasi means thalloid or seaweed type.$(47) Oosi korai: Needle type sedge.$(48) Neer korai: Neer refers to the watery substance, korai means sedge; a watery/fleshy sedge.$(49) Korai pasi: Korai means sedge, pasi means thalloid or seaweed type.$(50) Nool pasi: Thread like thalloid form.

Utility: Fresh leaf juice consumed to ease acid reflux. Stems fed to goats. Biomass used as green manure for garden.

Thalassia hemprichii (Ehrenb. ex Solms) Asch.

Purely marine; tidal and subtidal zones; black muddy, and loose sandy soils

Id: Rhizomes creeping, branched, brittle; leaves falcate; shoots brownish-black, internodes short, many.

Etymology:$(6) Kattai korai pasi: Kattai means woody and refers to the plant's stout rhizomes, korai means sedge, pasi means thalloid or seaweed type.$(7) Korai pasi: Korai means sedge, pasi means thalloid or seaweed type.$(8) Kadal korai: Kadal means sea, korai means sedge.

Utility: Dried rhizome powder consumed to treat mental disorders. The same powder mixed with coconut oil and applied on wounds. Biomass used as green manure for gardens.