=Water Loosestrife, Decodon verticillatus.=

1b. Stem herbaceous (4-10 dm. high; flowers purple, summer) --2.

2a. Flowers solitary in the axils; leaves mostly alternate
=Loosestrife, Lythrum alatum.=

2b. Flowers in terminal panicles; leaves opposite or whorled
=Loosestrife, Lythrum salicaria.=

MELASTOMACEAE, the Melastoma Family

Herbs, with opposite leaves with 3-5 principal veins; receptacle
urn-shape, bearing 4 sepals and 4 petals at its edge; stamens 8; ovary
4-celled, superior.

One species in Michigan, 3-4 dm. high, with purple flowers in late
summer =Meadow Beauty, Rhexia virginica.=

ONAGRACEAE, the Evening Primrose Family

Herbs with opposite or alternate simple leaves and regular flowers;
sepals and petals each 4 (or 2 in one genus), stamens 8 (or 2 in one
genus), attached to the summit or inside of a tubular receptacle; ovary
2-4-celled, inferior.

1a. Aquatic plant of shallow water or muddy ground, with prostrate stem
(flowers minute, axillary; petals small or none, summer)
=Water Purslane, Ludvigia palustris.=

1b. Land plants with erect or ascending stems --2.

2a. Petals minute, greenish (3-8 dm. high; late summer)
=False Loosestrife, Ludvigia polycarpa.=

2b. Petals yellow --3.

2c. Petals white, pink, purple, or red --9.

3a. Sepals borne at the summit of the ovary (5-10 dm. high; summer)
=False Loosestrife, Ludvigia alternifolia.=

3b. Sepals borne at the summit of the slender tubular receptacle, which
is prolonged beyond the ovary --4.

4a. Stamens all equal in length (Evening Primrose) --5.

4b. The alternate stamens longer (3-8 dm. high; summer) (Sundrops)
--8.

5a. Leaves deeply dentate or pinnatifid (2-5 dm. high; early summer)
=Evening Primrose, Oenothera laciniata.=

5b. Leaves entire or undulate or finely toothed (5-12 dm. high; summer)
--6.

6a. Hairs on the stem with broad reddish bases
=Evening Primrose, Oenothera muricata.=

6b. Hairs on the stem none, or without swollen bases --7.

7a. Stem and foliage glabrous, or with sparse spreading hairs
=Evening Primrose, Oenothe