Erect plants 1-2 m. high, with linear leaves and terminal spikes of brown flowers, appearing in summer.
| 1a. Staminate and pistillate portions of the flower-spike contiguous, the latter 2.5 cm. in diameter | Common Cat-tail, Typha latifolia. |
| 1b. Staminate and pistillate portions of the spike separated, the latter 2 cm. or less in diameter | Narrow-leaved Cat-tail, Typha angustifolia. |
SPARGANIACEAE, the Bur-reed Family
Marsh plants with linear leaves and spherical heads of inconspicuous greenish flowers, appearing in summer.
| About 5 species occur in Michigan, of which the commonest is | Bur-reed, Sparganium eurycarpum. |
NAJADACEAE, the Pondweed Family
Aquatic plants with submerged or floating leaves and inconspicuous flowers in summer.
| 1a. Leaves opposite or whorled [— 2.] | |
| 1b. Leaves alternate [— 2c.] | |
| 2a. Leaves thread-like, 3-8 cm. long | Horned Pondweed, Zannichellia palustris. |
| 2b. Leaves linear, toothed, abruptly dilated at the base, 3 cm. long or less (Naiad) [— 3.] | |
| 2c. Leaves entire, not abruptly dilated at base | [2]Pondweed, Potamogeton spp. |
| 3a. Leaves about 2 mm. wide, sharply and coarsely toothed | Naiad, Naias marina. |
| 3b. Leaves very narrowly linear, with numerous minute teeth | Naiad, Naias flexilis. |