ON SOME WATER PLANTS. 107
in colour, with bands of white spots, and are about the size of
marbles. I confess that when I first pulled one up from the
mud of a river-bed I thought for a moment I really had found
a marble or china bead, through which the runner had grown.
Arrowhead is abundant in England from Cumberland southward,
FIG 3.
FIG. 5.
it is rare in Ireland and only naturalized in Scotland: it is found
throughout Europe, North Asia and N. W. India.
The Butomus or Flowering Rush, often included in Alis-
maceae, still flourishes in the Roding and gladdens our eyes
with its umbels of pink flowers borne on long steins in mid summer;
the narrow leaves, triangular in section, are all aerial.
Another plant that often has ribbon-leaves is the smaller
Bur-reed, Sparganium simplex. In the forest ponds, where it