Euphorbia cyathophora (dwarf poinsettia, "Shojoso")

Japanese name: ショウジョウソウ （猩々草）
Scientific name: Euphorbia cyathophora

[Overview]
A perennial 60–100 cm tall.
It is not cold-hardy, so in Japan it is treated as an annual.
Milky white sap comes out when the stems or leaves are damaged.
Leaves are simple and alternate, oblong-ovate and about 6 cm long.
The leaf margins are irregularly and coarsely lobed.
At the branch tips the leaves are whorl-like, and their bases are colored vermilion and form bracts.
Small flowers are borne at the center of the bracts.
The flowers are borne in cyathia, enclosed in a green urn-shaped involucre, and have no perianth.
There is a single yellow gland.
The fruit is a spherical capsule 5 mm in diameter.

[History]
It was introduced in the Meiji era and has now become naturalized in warm regions such as Kyushu, the Ogasawara Islands and Okinawa.

[Cultivation]
Propagate from seed.
The optimum temperature for growth is 20–30°C and for germination 20–25°C, so sow only after the temperature has risen sufficiently.
It dislikes being transplanted, so when sowing directly, sow 5–6 seeds per spot with 25–30 cm between plants, and thin out the seedlings.
It prefers fertile soil that is sunny, well drained and moisture-retentive, but it is not very particular about soil type, and it is robust and grows well even if left alone.
In poor sun, the leaf color may be poor.
For potted plants, water thoroughly when the soil surface dries.
For plants in the ground, rainfall is sufficient.
It tolerates dryness.
If basal fertilizer is applied, no further fertilizer is particularly necessary.
It falls over easily in wind and rain, so provide a stake.
There are no particular pests or diseases.

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