Rhizoid

Evolutionary development:
– Plants originated in aquatic environments
– Gradually migrated to land during evolution
– Absorbed water from surroundings in water or near it
– Minimal tissue differentiation in primitive plant development
– Specialized water absorbing tissue developed to anchor to the ground

Description:
– Rhizoids absorb water mainly by capillary action
– Water moves up between threads of rhizoids
– Some bryophytes can take up water inside rhizoids
– Rhizoids in some species not as developed as roots
– Absorption mechanism differs in various plant species

Land plants:
– Rhizoids in land plants are trichomes
– Anchor the plant to the ground
– Absent or unicellular in liverworts
– Multicellular in mosses
– Known as root hairs in vascular plants

Algae:
– Some algae have extensive rhizoidal system
– Anchors alga to sandy substrate
– Allows absorption of nutrients
– Microscopic free-floating species lack rhizoids
– Rhizoids vary in structure and function among algae species

Fungi:
– Rhizoids in fungi are small branching hyphae
– Grow downwards from stolons
– Anchor the fungus to substrate
– Release digestive enzymes and absorb organic material
– Fungi are heterotrophs by absorption

See also:
– Fungi portal
– Rhizine, equivalent structure in lichens

References:
– Fletcher RL (1987)
– Jones VA, Dolan L (July 2012)
– Demes KW, Littler MM, Littler DS (2010)
– Smith GM (1955)