Why does E.Tenellus belong to E. family?

["Wong Chee Huey " <tyneside at singnet_com.sg>]

I've always wondered why E.Tenellus belongs to the sword family? It looks
unlike any other swords that I know of. Others have a blade of leaf attached
on the petiole but tenellus looks just like a narrow blade of grass.(blyxa
sp)

Moreover, tenellus propagate by runners which I do not see in other swords.
I've never tried growing it on land. Does it send a flower stalk with
plantlets growing on it?