Ageratina altissima (white snakeroot, "Marubafujibakama")

Japanese name: マルバフジバカマ （丸葉藤袴）
Scientific name: Ageratina altissima

[Overview]
A perennial 0.3–1 m tall.
It has long, creeping, branching rhizomes and often grows in colonies.
The stem is erect, branches well in the upper part, and has short hairs.
The leaves are opposite and ovate, about 15 cm long and 9 cm wide.
The leaf margins are toothed.
The petiole is 2–5 cm long.
Many white flower heads are borne in corymbs on the upper part of the stem.
The flower heads consist only of tubular florets.
The fruit is an achene with a white pappus.

[History]
Plants brought in as ornamentals around the middle of the Meiji era have become naturalized in various places.

[Cultivation]
Propagate from seed, by division, or by stem cuttings.
It prefers sun and soil that is well drained and retains moisture well.
When planting in the ground, avoid places with strong afternoon sun or dry conditions.
Because it spreads by sending out underground stems, to keep it from spreading too much, make a frame underground or plant it in a large pot and then bury the pot.
Take care not to let it run short of water; for potted plants, water thoroughly when the soil surface dries, and for plants in the ground, rainfall is sufficient unless summer brings sunny weather and dryness.
Too much fertilizer makes it leggy and reduces flowering, so none is particularly needed if base fertilizer is applied, but for potted plants diluted liquid fertilizer may be given in spring and autumn.
There are no particular pests or diseases.

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