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Seagrasses > Family Cymodoceaceae
Smooth ribbon seagrass
Cymodocea rotundata
Family Cymodoceaceae
updated Mar 14
if you learn only 3 things about them ...
This seagrass is rarely seen on our shores.
It doesn't flower frequently, and the flowers are small.
It is eaten by dugongs.

Where seen? There is a small patch of this seagrass on Chek Jawa and they have also been seen on Cyrene Reef.

Smooth ribbon seagrass is found throughout tropical Indo-West Pacific usually in clear water reefs, growing where it is exposed for only a short time during low spring tide. It is fast growing and believed to play a role in habitat recovery. It is not as well studied as Serrated ribbon seagrass (Cymodocea serrulata).

Features: Long ribbon-like leaves (0.5-1cm wide and 7-15cm long), with blunt, rounded tips that are smooth and not serrated. There are continuous leaf scars around the upright stem. It has thick rhizomes (underground stems). At intervals along the rhizome, a short stem emerges with 2-7 long leaves. The young leaves are fully enclosed by a leaf sheath which is sometimes dark coloured. The leaf sheaths around the leaf are not obviously flattened.

Sometimes confused with other ribbon-like seagrasses. Here's more on how to tell apart ribbon-like seagrasses.

Flowers and fruits: This seagrass has separate male and female plants. Flowering is rarely observed. The female flower appears in pairs at the base of the leaves. They have a prong-like stigma. The male flowers form within the leaf sheath. Seeds (10mm)are dark coloured with a hard-coated, beaked nut with a spikey central ridge along the length. The seeds are attached to the rhizome.

Role in the habitat: Dugongs eat this seagrass where smaller Halophila and Halodule are not available.

Status and threats: It is listed as 'Critically Endangered' on the Red List of threatened plants of Singapore.

This seagrass grows quite near
the Chek Jawa boardwalk.

Chek Jawa, Jun 09

Patches growing on an artificial beach
Tanah Merah, Jun 10

Thick rhizomes with 2-7 leaves.
Chek Jawa, Nov 06

After the oil spill in May 10.
Tanah Merah, Jun 10

Tanah Merah, Jun 10

Tanah Merah, Sep 11

Tanah Merah, Sep 11

Smooth ribbon seagrasses on Singapore shores

Photos of Smooth ribbon seagrasses for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

  • Waycott, Michelle (et. al). 2004. A Guide to Tropical Seagrasses of the Indo-West Pacific. 2004. James Cook University. 72 pp.
  • Calumpong, H. P. & Menez, E. G., 1997.Field Guide to the Common Mangroves, Seagrasses and Algae of the Philippines. Bookmark, Inc., the Philippines. 197 pp.
  • Hsuan Keng, S.C. Chin and H. T. W. Tan.1998, The Concise Flora of Singapore II: Monoctyledons Singapore University Press. 215 pp.
  • Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
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