Description :

• Submerged, fern-like, annual or rarely perennial herbs found on rocks in fast-flowing freshwater, dioecious or rarely monoecious; rhizome discoid or tuberous, forming a compact circle of roots, firmly attached to rocks
• Leaves basal, 2- or 3-pinnatifid, petiolate, dilated and ligulate at base, petiole and rachis densely covered with warty to tongue-shaped protuberances; pinnae dissected into multifid, variously-shaped outgrowths ('gill-tufts')
• Inflorescence emergent, densely spicate (resembling fruiting spikes of Plantago major); scape verrucose or rarely smooth
• Flowers unisexual, small, sessile, solitary in axils of spirally arranged, closely imbricate bracts; calyx and corolla 0
• Male flowers consisting of one sessile or subsessile stamen with 2 oblong thecae; pollen in tetrads, copious
• Female flowers : ovary superior, of 2 fused carpels, 1-locular, many-ovuled, with 2 parietal placentas; styles 2, exserted from the bracts, persistent
• Fruit a 2-valved capsule, enclosed in persistent bract
• Seeds small, light, many; endosperm 0

Classification Notes:

• In habit the family closely resembles Podostemaceae , and the two were formerly often considered to be affiliated. Recently Hydrostachyaceae has been placed in or near SCROPHULARIALES, LAMIALES or PLANTAGINALES. Chemical data support affiliations with BRUNIALES

Nomenclature:

• Hydrostachyaceae
  • Podlech: 1 (1966)
  • Obermeyer: 211 (1970)
  • Cusset: 75 (1973)
  • Cook: 105 (1990)
  • Scogin 471 (1992)
  • Stannard 10 (1997)

Distribution & Notes:

• Global : Genus 1, species 22, Africa south of the equator and Madagascar
• Southern Africa : Genus 1, species 1

References:

• COOK, C.D.K. 1990. Aquatic plant book . SPB Academic Publishing, The Hague
• CUSSET, C. 1973. Révision des Hydrostachyaceae . Adansonia , sér. 2, 13 (1)
• OBERMEYER, A.A 1970. Hydrostachyaceae . Flora of southern Africa 13
• PODLECH, D. 1966. Podostemaceae . Prodromus einer Flora von Südwestafrika 61
• SCOGIN, R. 1992. Phytochemical profile of Hydrostachys insignis ( Hydrostachyaceae ). Aliso 13(3)
• STANNARD, B.L. 1997. Hydrostachyaceae . Flora zambesiaca 9,2

Resources:

• Hydrostachyaceae genus: Hydrostachys