SafePlants

Donax and Arundo donax: A Tale of Two Genera

The name Donax is applied to two distinct genera of organisms: one of saltwater clams (bivalves) and another of plants. This article will discuss both, although focusing primarily on Arundo donax.

Donax (Bivalve)

• Common Names: Bean Clam, Coquina Clam
• Scientific Name: Donax
• Taxonomy:
  • Kingdom: Animalia
  • Family: Donacidae
• Species Examples: Donax variabilis (Coquina), Donax trunculus, Donax rugosus, Donax denticulatus, Donax vittatus
• Synonyms: Donax (Chion)
• Distribution and Habitat:
  • Donax trunculus: Native to the Mediterranean and Atlantic coasts of western Europe.
  • Donax variabilis: Eastern coast of the United States (New York to the Caribbean), Gulf of Mexico.
  • Donax denticulatus: Carenero Beach, Southeastern Cuba
  • Occurs on sandy beaches along coasts worldwide.
• Morphological Characteristics:
  • Shell size up to 39mm.
  • Thin, solid shell structure.
  • Equivalve.
  • Inequilateral (beaks behind midline).
  • Not tumid.
  • Donax vittatus has a roughly wedge-shaped, shiny shell up to 3.8 cm long with the umbones close to the posterior end.
• Ecological Role:
  • Prolific filter feeder, providing an important link in coastal food chains.
  • Indicator species for coastal health.

Arundo donax (Plant)

• Common Names: Giant Reed, Spanish Reed, Colorado River Reed, Giant Cane, River Cane, Bamboo Cane, Donax Cane, Arundo Grass, Giant Reed Grass
• Scientific Name: Arundo donax L.
• Taxonomy:
  • Kingdom: Plantae
  • Family: Poaceae (Gramineae) - Grass Family
• Synonyms: Arundo maxima, Arundo versicolor, Cynodon donax, Donax arundinaceus, Donax donax, Arundo glauca, Arundo latifolia, Arundo longifolia
• Distribution and Habitat:
  • Native to eastern and southern Asia, and possibly parts of Africa and the southern Arabian Peninsula.
• Ecological Role:
  • Invasive in riparian areas, altering hydrology, nutrient cycling, and fire regimes.
  • Displaces native species.
  • Can form dense stands in water.
• Morphological Characteristics:
  • Deciduous rhizomatous perennial, forming spreading clumps.
  • Bamboo-like stems, reaching up to 5m (19ft) tall and 4m (13ft) wide.
  • Strap-shaped blue-green leaves.
  • Tall, erect, cane- or reed-like grass, 2 to 8 meters high.
  • Many-stemmed, cane-like clumps, spreading from horizontal rootstocks.
  • Very large, feathery, plume-like inflorescences.
• Growth Habits:
  • Perennial growing to 6 m (19ft) by 4 m (13ft) at a fast rate.
  • It is hardy to zone (UK) 6.
  • Flowers in September, seeds ripen in.
  • Easily grown in full sun to light shade a wide variety of soils ranging from light sandy ones to heavy clays.
  • Plants perform well in moist to wet soils.
• Interactions with Humans:
  • Used for musical reeds and industrial cellulose.
  • Historically used as windbreaks.
  • Potential biochar and biofuel crop.
  • Ornamental garden plant.