Yellow glandweed (Parentucellia viscosa) was introduced to North America from the Mediterranean. It now inhabits mostly coastal areas in the Pacific States and there is a population in East Texas. It spreads rapidly and is considered an invasive/noxious weed.
A member of the Broomrape Family (Orobanchaceae), yellow glandweed is also colloquially known as yellow parentucellia and yellow bartsia. Its habitat is disturbed wetlands, fields and pastures as well as moist grasslands below 2,000 feet.
An annual, yellow glandweed has fibrous roots. The simple, unbranched stems and leaves are covered with short, sticky, glandular hairs. These glandular hairs give yellow glandweed the species designation, viscosa, which means “sticky”.
The opposite, lanceolate leaves have toothed edges and prominent veins. The largest leaves with the coarsest teeth are at the base of the stem and become smaller and more bract-like below the flower heads.
The yellow glandweed inflorescence is an elongated raceme (unbranched, opening from the bottom up) at the end of the stem. A green calyx of four lanceolate, united sepals surrounds the five yellow petals which are arranged into two lips. The upper lip is entire and arches to form a hood. The lower lip is divided into three rounded lobes. Enclosed within the petals are two unequal pairs of stamens and a superior ovary.
The green, cylindrical fruits project just beyond the calyx and contain many small, lance-shaped seeds.
Tomaso Parentucelli (1397 – 1445), who became Pope Nicholas V, is honored by the genus designation.
These yellow glandweed plants were growing in June at the start of the Dead Lake Trail in Tolowa Dunes State Park near Crescent City CA.