floating leaves. For the identification of the species the Manual must
be used.

JUNCAGINACEAE, the Arrow Grass Family

Marsh plants, with linear cylindrical leaves and inconspicuous flowers
in spikes or racemes, appearing in early summer.

1a. Leaves all basal; flowers numerous in a spike-like raceme (Arrow
Grass) --2.

1b. Stem-leaves present; flowers in a loose bracted raceme (1-3 dm.
high). =Scheuchzeria, Scheuchzeria palustris.=

2a. Fruit (usually to be seen at the base of the raceme) ovoid or
oblong, rounded at the base =Arrow Grass, Triglochin maritima.=

2b. Fruit linear, narrowed at the base (1-5 dm. high)
=Arrow Grass, Triglochin palustris.=

ALISMACEAE, the Water Plantain Family

Marsh plants, with scape-like stems; flowers with 3 green sepals, 3
white petals, 6 or more stamens, and several separate pistils.

1a. Ovaries in a ring; flowers in panicles (2-8 dm. high, summer)
=Water Plantain, Alisma Plantago-aquatica.=

1b. Ovaries in a head; flowers in racemes or umbels --2.

2a. Flowers all perfect, in a single umbel of 2-8 flowers; stamens
9 (leaves lanceolate; 15 cm. high or less; summer)
=Dwarf Water Plantain, Echinodorus tenellus.=

2b. Flowers in a raceme of 3-flowered whorls, the lower pistillate,
the upper staminate; stamens usually more than nine (1-10 dm.
high, summer) (Arrow-head) --3.

3a. Leaves ovate to linear, not sagittate at base --4.

3b. Leaves broad or narrow, sagittate at base --5.

4a. Pistillate (basal) flowers sessile or nearly so (2-8 dm. high,
summer) =Arrow-head, Sagittaria heterophylla.=

4b. Pistillate flowers with obvious pedicels
=Arrow-head, Sagittaria graminea.=

5a. Basal lobes of the leaf conspicuous, triangular, almost or quite as
long as the terminal portion --6.

5b. Basal lobes small, short, linear --4b.

6a. Beak of the achene very short and erect; rare species
=Arrow-head, Sagittaria arifolia.=

6b. Beak of the achene sharp, incurved at right angles to the body;
common species =Arrow-head, Sagittaria latifolia.=

HYDROCHARITACEAE, the Frog's Bit Family

Submerged aquatics, with inconspicuous flowers in