Silene latifolia subsp. alba (white campion, "Matsuyoisenno")

Japanese name: マツヨイセンノウ（待宵仙翁）
Scientific name: Silene latifolia subsp. alba

[Overview]
A biennial or perennial up to 1 m tall.
The stems and leaves have slightly sticky hairs.
The stem branches freely.
Leaves are simple and opposite, lanceolate to oblong, 4–10 cm long, with coarse hairs on both surfaces.
The leaf margins are entire.
The plant is dioecious.
Both male and female plants bear cymes at the stem tips with many flowers.
The flowers are white, 5-petaled, about 2.5–3 cm across.
The petals open flat and are deeply 2-lobed at the tip.
The lower part of the flower is enclosed in an urn-shaped calyx marked with dark stripes.
There are 10 stripes in male flowers and 20 in female flowers.
The flowers open from evening and are fragrant.
The fruit is a capsule.

[History]
It is said to have been introduced as an ornamental in the Meiji era, and it has become naturalized throughout Japan.

[Cultivation]
Propagate from seed.
It also spreads readily from self-sown seed.
It prefers sunny, well-drained, slightly alkaline soil.
Cultivation is easy.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient.
Fertilizer is not particularly necessary for plants in the ground; for potted plants, apply slow-release fertilizer in spring and autumn.
There are no particular pests or diseases.