They are said (by some taxonomy experts) to be two differing sub-species of Bulbous Rush:

• (Juncus bulbosa ssp. bulbosus)
• (Juncus bulbosa ssp. kochii)

If there are two sub-species, as claimed by some books, then:

The first batch of photos growing half submerged in water from Coniston Coppermines Valley are perhaps ssp. kochii which has stems more often erect and the fruit capsule shiny dark brown.

And the second batch of photos drooping from a flowerpot might be ssp. bulbosa with the fruit capsule matt light-brown.

However, the exact way(s) in which they differ or are to be differentiated by varies between two opinions; and with some experts question the validity of the two sub-species. It might just be that it is actually, as some books say, highly variable.

Uniquely identifiable characteristics

Distinguishing Feature : For a Rush - the tri-lobed fruits are a dead giveaway. The short bunches of tapering needle-like leaves at every stem junction.