Branched Bur-reed

Sparganium erectum

The Branched Bur-reed gets its name from its globular spiky ("Bur"-like) flowerheads which are arranged on a branching spike ("Branched"). It is a close relative of the larger plant Reed Mace; together, the two plants make up belts of reeds in shallow bodies of water in marshy habitats characterized by sedimentation.

This plant grows to heights between 50 and 150cm. At its base are triangular distichous (e.g. in vertical rows on opposite sides of the stem) leaves. The keeled leaves are bright green and make the plant easy to differentiate – even when not flowering – from the more blue-green Reed Mace. False identification is however possible in the case of vegetative specimens of the Butomus (also known as flowering rush). The main differences are in the reddish-hued base of the leaves and the small bulbs on the main rhizome of the flowering rush. Unlike other types of this genus, the Branched Bur-reed does not form floating leaves. The branched flowering stem has both male and female flowerheads: on top the male flowerheads in spikes, and below the round female flowerheads in clusters. Flowering takes place in the months June to August. The plant propagates by way of thin rhizomes.

The Sparganium genus comprises around 20 different types, nearly all of which are native to the northern hemisphere. Only one type grows south of the Equator – in New Zealand. Its range extends from Northern Africa to the Arctic Circle and east to Japan. This reed species populates the edges of stagnant and slow-moving bodies of water including ponds, ditches, and marshy swamps. As long as the water is rich in nutrients, the plant may be found up to montane-level elevations.

Endangerment and Conservation Status
The most common representative of its genus in Austria, the Branched Bur-reed may be found in all provinces. Various subspecies exhibit varying degrees of vulnerability. In accordance with the Vienna Environmental Protection Act, all subspecies of the Sparganium genus are protected, at least in part.

Ecological Characteristics
The Branched Bur-reed prefers reed beds located in waters from 30-60cm deep. The male flowers bloom first, then the female. Pollination takes place, as with many reeds, through dispersal by wind. The spiky globular fruitheads fall apart when ripe and break into small, spongy (e.g. floating) fruits which are dispersed by both water and waterfowl. They germinate particularly well in recently dried muddy soils; within a closed reed bed, germination is nearly impossible. Instead, established plants propagate by forming runners. In its root system, the Branched Bur-reed divides work up among its anchor roots and the so-called feeding roots, which are specialised in seeking nourishment.

Special Characteristics
Fossilised remains of the Branched Bur-reed have been found in excavations of prehistoric pile dwellings. Its long leaves were likely used to thatch roofs. The edible lower parts of the stem are juicy and can be enjoyed raw or cooked as wild vegetables.