SafePlants

Halodule: A Genus of Seagrasses

Halodule is a genus of seagrasses belonging to the family Cymodoceaceae, first described as a genus in 1841. These plants play a vital role in marine ecosystems around the world.

Considerations for Pets

• The text mentions that Halodule species are sometimes found mixed with other seagrasses on shores. While generally not considered toxic, it's always a good idea to supervise pets in coastal environments to prevent them from ingesting large quantities of any plant material.

Scientific Name and Common Names

• Scientific Name: Halodule
• Common Names:
  • Narrowleaf seagrass (for Halodule uninervis)
  • Shoalweed, Shoalgrass (for Halodule wrightii)

Taxonomy and Nomenclature

• Family: Cymodoceaceae
• Kingdom: PLANTAE
• Division: ANTHOPHYTA
• Class: MONOCOTYLEDONEAE
• Order: HELOBIAE
• Synonyms: Diplanthera Thouars (1806), not Gleditsch (1764)

Distribution and Habitat

• Halodule species are widespread on tropical and semi-tropical ocean shores worldwide.
• Specific locations mentioned include:
  • Western Pacific and Indian Oceans (Halodule uninervis)
  • Seacoasts of warmer oceans, including California and Texas (Halodule wrightii)
  • Coastlines of Malaysia (Halodule uninervis and Halodule pinifolia)
  • Gulf of Mexico (Halodule wrightii)
  • Kuwait Bay (Halodule uninervis)
  • Mexico (Halodule spp. and Halophila decipiens)

Ecological Role

• Halodule wrightii can form carpet-like beds in warm, shallow waters, providing habitat for various marine organisms.
• Halodule wrightii and Syringodium filiforme play a role as pioneers in the succession of seagrass communities.

Morphological Characteristics and Growth Habits

• Halodule wrightii is a "seagrass" that may form carpet-like beds in warm, shallow waters.
• Halodule uninervis is a thin, flat, needle-like seagrass, sometimes mixed with other seagrasses.
• Halodule species have rhizomes that are branched and root at the nodes.
• Halodule pinifolia has a trident leaf tip with one central longitudinal vein and a rhizome that is usually pale ivory with clean black leaf scars.
• Halodule wrightii is dioecious, meaning it has male and female flowers on separate plants.
• Seeds of Halodule wrightii have a hard seed-coat and form a persistent seed bank.

Interactions with Other Organisms

• Dugongs are mentioned as preferring Halodule pinifolia as a food source.
• The community structure of the ichthyofauna (fish) is associated with seagrass beds of Halodule wrightii.
• The shoot density of Halodule wrightii influences the composition of the associated algal community.

Further Information

• ARKive (for Seagrass photos and facts)
• WoRMS (World Register of Marine Species) taxon details
• IUCN Red List (species range map for Halodule pinifolia)
• JEM Technical Report (2007, Stressor response models for Seagrasses, Halodule wrightii and Thalassia testudnium)
• Wikimedia Commons (File:Halodule uninervis.jpg)