Hornworts

Rigid Hornwort Soft Hornwort Soft Hornwort Rigid Hornwort

What are they?

These are submerged, perennial aquatic plants that are free-floating in the water column and do not produce roots. Segments of stem that break off are capable of continuing to grow as separate plants. Hornworts are popular oxygenating plants for garden ponds.

Where are they found?

These are plants of still or slow-moving water, typically found in a range of ponds, ditches, dykes and slow-moving waterways.

Identification

Hornworts are rather distinct in appearance from other subaquatic plants in our region. They have leaves carried in whorls on the stems and which are reduced to the veins with little in the way of an actual leaf surface; this gives them the look of a bottlebrush. Their flowers are very small and appear singly in the leaf axils, with male and female flowers appearing separately but on the same plant. The two species are very similar, but can be told apart by checking the number of times that the leaves are divided.



Rigid Hornwort      Ceratophyllum demersum

Native. Widespread and often quite common in a wide range of still or slow-moving, permanent waterways, especially in Fenland and Broadland. Flowers July to September. Best told from Soft Hornwort by its leaves, which are forked only one to two times.

Rigid Hornwort Rigid Hornwort Rigid Hornwort Rigid Hornwort
Habit
Habit
Leaves
Leaves
Rigid Hornwort Rigid Hornwort
Leaf segments
Leaf segments


Soft Hornwort      Ceratophyllum submersum

Native. Widespread but far less common than Rigid Hornwort and mostly found in well-maintained dykes and ditches near the coast. Flowers July to September. Best told from Rtigd Hornwort by its leaves, which are forked three or more times.

Soft Hornwort Soft Hornwort Soft Hornwort Soft Hornwort
Habit
Habit
Leaf segments
Seed capsule