Some similarities to other Bur-reeds:
- Un-branched Bur-reed (Sparganium emersum), but that is without branches on the stem and is only half the maximum height, 60cm.
- The similarly short (up to 60cm in length)
Floating Bur-reed (Sparganium angustifolium) but that has floating leaves and only two male flowers and between 2 and 4 female flowers, and it prefers shallow peaty acidic waters.
- The shortest at just 30cm
Least Bur-reed (Sparganium natans) which has but one male flower with narrower (2-6mm) leaves. May also grow in alkaline waters.
Not to be confused with :
Bur-Marigolds such as London Bur-Marigold or Nodding Bur-Marigold [plants with similar name from a different family].
The Genus Sparganium [which was the sole member of the Bur-Reed (Sparganiaceae] Family) has more recently been found to more closely match the Family Typhaceae, which is to where the Sparganiaceae Family has now been subsumed.
There are 4 sub-species:
It is not known to which sub-species (possibly plural) the above photos represent - none of the fruits are yet ripe (brown of any shade), it depends exactly how gradual is 'gradually' and how abrupt is 'abrupt'... But in the photos of the fruiting heads - if the expanded fruits are ripe, then there are very few of them per head, so, ipso facto - they must be the ssp. oocarpum...
Branched Bur-reed (Sparganium erectum ssp. erectum) - Central & Southern Britain & IOM. Fruits often dark-brown and flat-topped apart from the beak in the centre.
Branched Bur-reed (Sparganium erectum ssp. microcarpum) - All Britain, Ireland & IOM. Fruits often dark-brown at apex with rounded top which narrows abruptly to a beak.
Branched Bur-reed (Sparganium erectum ssp. neglectum) - Throughout Britain & Ireland. Fruits pale-brown, ellipsoidal, only gradually narrowing to a beak.
Branched Bur-reed (Sparganium erectum ssp. oocarpum) - The dominant sub-species. Fruits pale-brown nearly globular and abruptly narrowing to a beak. Usually very few fruits form per head. This is possibly the hybrid between ssp. erectum and ssp. neglectum.
It is an aquatic perennial plant that grows in or besides still(ish) fresh-water such as canals. The fruiting heads are globular, with many beaked fruits - much like a mediaeval mace! The leaves are long, linear and deeply keeled for rigidity, standing much taller than the flowers. It is monoeciuos, with separate male and female flowers on the same plant. Floating leaves are rare on this species; they are much more common on
Floating Bur-reed (Sparganium angustifolium)