154


White and Greenish


Any plant which elects to grow in shallow water must be am-
phibious ; it must be able to breathe beneath the surface as the fish
do, and also be adapted to thrive without those parts that corre-
spond to gills ; for ponds and streams have an unpleasant way of
drying up in summer, leaving it stranded on the shore. This ac-
counts in part for the variable leaves on the arrow-head, those
underneath the water being long and ribbon-like, to bring the
greatest possible area into contact with the air with which the
water is charged. Broad leaves would be torn to shreds by the
current through which grass-like blades glide harmlessly ; but
when this plant grows on shore, having no longer use for its lower
ribbons, it loses them, and expands only broad arrow-shaped sur-
faces to the sunny air, leaves to be supplied with carbonic acid to
assimilate, and sunshine to turn off, the oxygen and store up the
carbon into their system.
Water Arum: Marsh Calla
(Calla palustris) Arum family


Flowers—Minute, greenish yellow, clustered on a cylinder-like,
fleshy spadix about 1 in. long, partly enfolded by a large,
white, oval, pointed, erect spathe, the whole resembling a
small calla lily open in front. The solitary ‘‘flower” on a
scape as long as the petioles of leaves, and, like them, sheathed
at base. Leaves : Thick, somewhat heart-shaped, their spread~
ing or erect petioles 4 to 8 in. long. Fruit: Red berries clus-
tered in a head.
Preferred Habitat—Cool Northern bogs; in or beside sluggish
water.
Flowering Season—May—June.
Distribution—Nova Scotia. southward to Virginia, westward to
Minnesota and Iowa.
