Glaudicium is a genus of herbaceous plants of the family Ranunculaceae. The genus consists of a single species, Glaucidium palmatum, also known as Japanese wood poppy. This plant is endemic to northern and eastern parts of Japan, but it is also cultivated in gardens in the United Kingdom, Canada, and the United States. It grows into a shrub with lobed leaves and upright stems, with a single pink, purple, or white flower atop each stem. The wood poppies are best planted in shady areas with moist soil, but they are vulnerable to fungal and insect attacks.
Most classifications include this plant under the family Ranunculaceae, but some botanists place it under its own family, Glaucidiaceae. Some gardeners and plant enthusiasts highly value these plants for their rarity and use them as border plants or woodland garden highlights. The colorful flowers provide a striking contrast to a green backdrop.
Glaucidium plants form a mass that can grow to a height of 18 to 24 inches (45 to 60 cm), and their stems form together into a small shrub-like clump. The lobed leaves can grow 12 to 18 inches (30 to 48 cm) wide. Leaves grow in pairs from a single upright stem and become smaller as they ascend the stem.
On top of each stem is a solitary, drooping cup-shaped flower about 3 to 4 inches (7 to 10 cm) wide that consists of four petals with many stamens. Glaucidium flowers bloom every year from May to June. It will take one of these plants approximately four cycles of blooming seasons before its maximum flower size is achieved.
This plant thrives in its natural wild habitat under the shade of deciduous forests in Japan. When planted in a garden, it is best to provide the plant with the same shady conditions. Glaucidium grows only in soil that is cool, moist, and rich with humus. Outside its natural habitat, constant watering is important for the plant to survive. It is best to allow the ground to completely dry in between watering it.
Humid and windy conditions can kill this plant. It can tolerate cold temperatures to some extent. The aerial parts may wilt due to frost during winter, but will recover easily when temperatures rise.
Glaucidium seeds typically take up to two years to germinate. Seedlings turn into dormant buds that are attached to a horizontal rootstock. Portions are then cut and planted around 15 to 18 inches (38 to 45 cm) from each other to provide ample space for future growth. This plant is vulnerable to insect and fungal attack, and preemptive insecticide and fungicide application before the plant blooms is recommended.