Anubias

Anubias barteri and A. barteri nana. Anubias is a marsh plant from tropical West Africa.  It its native haunts it is seldom flooded for long, but in the aquarium it will adapt to submerse life. Each leaf arises out of a sheaf, within which the next leaf develops. It emerges furled tight as a Milanese umbrella, then unfurls from the left margin.
 
Anubias grows very slowly under water, and traditional commercial propagation from axillary shoots and rhizome divisions have been so slow that the retail price has remained high; commercial tissue culture techniques that are maturing in the Far East will bring down prices. For the aquarist, though, each leaf lasts for a couple of years; after a few years you'll have masses of it if you'll periodically slice off the growing ends together with the four or five newest leaves and the roots. The remainder will sulk for a month or so, frustratingly long for commercial growers, then branch. The growing tip will scarcely pause.
 
As older leaves become overgrown with algae or ratty around the edges, you'll want to remove them: lever the leaf stalk backwards, gripping it near the rhizome, and it will come away cleanly, without a stub to rot away. A dormant bud lies under the rind of the rhizome there at the upper base of the petiole: it won't be damaged. Side growth will occur at one of these nodal points, and side growth is the only usual way to get more Anubias plants.
 
Various fancy and descriptive sub-specific names are given this variable plant: mine was purchased years ago as A. b. caladiifolia, because the bases of the leaves were cordate, that is, extended downwards at the base like those of a Caladium; in its constantly submerged life with me, its leaves are less robust and more typically ovate, with a gently waved edge.  A. barteri nana, originally collected from Victoria, Cameroons, and the most widely available Anubias, is a genuine dwarf, with leaves that may diminish to the size of a fingernail, or extend to a couple of inches long, if its roots have found their way from the submerged wood you've pinned it to, into a rich substrate.
 
I find that if I clip a root at about an inch length it will proliferate into a mass of slender roots, which may better suit my purpose.
 
Never bury the thin rhizome from which the leaves emerge. Under the substrate it's very likely to rot. Instead attach a length of rhizome to a thin branch of wood by wrapping the rhizome with a length of  that wire wrapped in green plastic that you buy in a spool at a house plant shop. When the roots have clung securely to the wood, you can remove the strip of waterproof twist-tie, which you won't discard, but save for reuse.