Evening Primrose Family (Onagraceæ)
A family of herbs or shrubs with perfect, usually four-parted flowers, four petals, four sepals, four or eight stamens and a two- or four parted stigma.
(A) Great Willow Herb; Fireweed (Epilobium angustifolium) springs up in profusion and attains its greatest growth in clearings or recently burned land.
The tall, upright stem is usually simple, but occasionally slightly branched at the top. It attains heights of from 2 to 8 feet.
The flower spike is long; the flowers, blooming from the bottom upward, leave upright, long, slender pods.
The Great Willow Herb is abundant throughout our range in low ground, blooming during July and August.
(B) Hairy Willow Herb (Epilobium hirsutum) (European) has become naturalized and is fairly common in waste places and about old dwellings. It is branchy, hairy, has finely toothed, stemless leaves, and four-parted magenta flowers growing from the angles of the upper leaves.
(A) Evening Primrose (Œnothera biennis) is an exceedingly common biennial plant, of nocturnal habits, the flowers spreading wide open at dusk and partly or wholly closing the next morning.
The stem is soft-hairy, quite stout, and often very tall, ranging from 1 to 6 feet in height. Both the stem and the leaves are rather coarse in texture. The flowers are seated in the angles of the upper leaves. The four pale lemon-yellow petals are large and rounded, the flower spreading slightly less than two inches.
The lower buds open first, only a few at a time, so that usually we may find seed-pods seated among the leaves just below the flowers and undeveloped buds and leaves above. Primrose blooms in fields and roadsides, everywhere, from July to September.
(B) Sundrops (Œnothera fruticosa) a somewhat similar, diurnal species, with a branched stem, grows 1 to 3 feet high. The pale-yellow flowers measure from ½ to 1 inch across; they are in loose, terminal clusters or from the angles of the upper leaves. The leaves are linear-lanceolate, slightly toothed. Common from Me. to Minn. and southward.