Adenostemma lavenia ("Numadaikon")

Japanese name: ヌマダイコン （沼大根）
Scientific name: Adenostemma lavenia

[Overview]
A perennial 0.3–1.3 m tall, growing beside waterways and in wetlands.
It has slender rhizomes.
The stem often creeps along the ground at the base and roots, branches, and is erect in the upper part.
The leaves are simple, sparsely opposite in 4–8 pairs, ovate-oblong; those in the middle of the stem are 4–24 cm long including the petiole and 1.5–7 cm wide, with a petiole 1–4 cm long.
The leaf tip is pointed, the base is rounded to wedge-shaped, and there are 4–20 pairs of low, blunt teeth.
The leaves are sparsely covered with short hairs.
White flower heads are borne several at a time in corymbs at the tips of long stalks, and each flower head has a short, hairy stalk.
Each flower head consists of about 20 florets, and the corolla is tubular, about 2.5 mm long, and shallowly 5-lobed.
The involucre is spherical, about 1 cm across, and the involucral bracts are arranged in 2 rows and joined at the base.
The fruit is an oblanceolate achene about 3.5 mm long; when ripe and dry it turns pale brown and is covered with glossy, scab-like projections, whose tips often look like glandular dots.
The pappus is club-shaped, with 3–4 elements arranged radially, and secretes a sticky fluid.

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