Willowherbs  ( Epilobium ciliatum, E. brachycarpum)

Willowherbs are native broadleaf plants but usually require a disturbance to establish. Although considered desirable members of natural habitats, they can be weedy in managed urban and agricultural sites. Two species of willowherbs common in California are the perennial fringed willowherb, E. ciliatum, and tall annual willowherb, E. brachycarpum, a summer annual.

Fringed willowherb is found throughout California to 13,500 feet (4100 m). It inhabits moist or dry disturbed areas in plant communities including those in meadows and wetlands, in agricultural areas, wet and moist sites, and nurseries. Tall annual willowherb is found throughout California, except for the Channel Islands and deserts, to 11,000 feet (3300 m). It inhabits dry, open sites in many plant communities, unmanaged, disturbed areas, landscaped areas, and agricultural sites.

Habitat

Fringed willowherb–many plant communities, meadows, wetlands, streambanks, ditches, irrigation canals, nurseries, orchards, vineyards, and landscaped areas. 
Tall annual willowherb–fields, agronomic crop fields, orchards, vineyards, forestry sites, and roadsides.

Seedling

In both fringed willowherb and tall annual willowherb, leaves are initially opposite to one another and sometimes are tinged red.

Fringed willowherb: Cotyledons (seed leaves) are egg shaped with a rounded to
slightly squared tip and hairless. The first true leaves are oval.

Tall annual willowherb: Cotyledons are broadly egg shaped to almost round, approximately 1/8 to 1/5 of an inch (3–5 mm) long and wide, hairless, with a slightly squared tip. The first true leaves are oblong football shaped, about 2/5 to 3/5 of an inch (10–14 mm) long and approximately 1/8 to 1/5 of an inch (3–5 mm) wide, hairless, and with edges that sometimes have weak teeth.

Mature plant

Fringed willowherb is a loosely clumping plant usually with more than one stem from the roots that branch in the upper portion. Stems are weakly woody but not peeling at the base as occurs in tall annual willowherb, and sometimes reddish. The mature plant can grow to about 6-1/2 feet (2 m) tall. Leafy rosettes are usually found at the base of the plant. Leaves are lance shaped or football to egg shaped, range from about 2/5 to 6 inches (1–15 cm) long, sometimes tinged red, have short stalks or no stalks, and usually have serrate edges. Leaves are opposite to one another along the base of the stem and generally are alternate to one another above it. Lower leaves are hairless or hairy, while upper leaves are sparsely to densely hairy. Upper leaves do not have clusters of smaller leaves where their stalks meet the stem (axils) as is found in tall annual willowherb.

Tall annual willowherb grows erect and usually has one main stem that branches in the upper portion, is weakly woody, and peels at the base when mature. Branches grow ascending (sloping upward) to almost straight and are nearly hairless, except for the tips, which often have some glandular hairs. The plant can grow to about 6-1/2 feet (2 m) tall. Leaves are narrowly football shaped, mostly 2/5 to 2 inches (1–5 cm) long, nearly hairless, often fold upward, have no stalks or very short stalks, and have edges that are smooth or have a few small teeth. Often the upper leaves have clusters of smaller leaves where their stalks meet the stem (axils).

Flowers

Flowers have four, white to violet-pink notched petals, which are produced at the end of long, slender stalks that attach along the flowering stem forming a flower head.

Fringed willowherb flowers bloom from June through September. The flowering head is covered sparsely to densely with hairs that are sometimes glandular, and leaves remain attached to it.

Tall annual willowherb flowers bloom from May through September. Flower heads are nearly hairless and have very few leaves. Flower stalks generally have some glandular hairs.

Fruits

Fruits consist of slender, straight, cylindrical capsules with four chambers. Capsules eventually split open and peel back, exposing the seeds.

Fringed willowherb: Capsules are 3/5 to 4 inches (1.5–10 cm) long, hairy, and stalkless or have long stalks.

Tall annual willowherb: Capsules are 3/5 to 1-2/5 inches (1.5–3.5 cm) long, hairless or have glandular hairs, and have long stalks.

Seeds

Seeds are egg shaped, flattened, and end in a tuft of long, soft hairs.

Reproduction

Reproduces by seed.

More information

• Broadleaf ID illustration
• Fringed willowherb, Epilobium ciliatum ssp. ciliatum Calflora's distribution map
• Tall annual willowherb Calflora's distribution map
• For agriculture: UC IPM Pest Management Guidelines