Invasive Plants, Pacific Northwest
The Butter & Egg Plant grow all over the Pacific Northwest and is a common sight. This introduced perennial plant is up to 60 cm tall with straight stems and very little branching. The alternate leaves are densely distributed all around the central stem, appearing to be opposite or whorled. They are up to 6 cm long and 0.3 cm across, pale or grayish green, linear with smooth margins, and hairless. The central stem has a few hairs near its apex, but becomes slightly woody near the base. This stem terminates in a raceme of flowers that is up to 8 cm long.
The flowers are distributed all around this raceme. Each flower is about 2.5 cm long with an upper and lower lip that is more or less yellow; there is also a long spur at the end of the corolla that hangs downward. The blooming period occurs from early to mid summer and lasts about a month, and then intermittently thereafter until the early fall.
Some groups of plants bloom later than others depending on shade conditions. Each flower is replaced by a seed capsule that contains many small seeds. Each seed is brown, flattened and surrounded by a rather large papery wing with a small notch on one side. Assisted by these papery wings, the seeds are blown about by the wind.
The root system consists of a long taproot and shallow rhizomes that spread in all directions. This plant usually forms colonies by means of its rhizomes. But will pioneer new areas by seed.
The preference is full sun, dry conditions and a barren soil that is gravelly or sandy. Under these conditions, this plant can spread aggressively because of the reduced competition from taller plants with wider leaves. The flowers are pollinated by bumblebees, which are strong enough to push past the palate to enter the throat of the corolla.
Butter & egg is another garden plant that has escaped into the wild to become a permanent resident. It has spread to all areas of the coast.