Dipsacus japonicus Seeds | Japanese Teasel

Japanese Teasel (Dipsacus japonicus) with its tall spiny stems and oval flower heads banded with rings of pale flowers — Japanese Teasel (*Dipsacus japonicus*): Caprifoliaceae, a tall biennial of East Asian waysides, close relative of the drug plant Xu Duan.

LATIN NAME: Dipsacus japonicus

COMMON NAME: Japanese Teasel

Plant Profile

Japanese Teasel is a tall biennial of East Asian roadsides and field margins, spending its first year as a flat rosette of spear-shaped leaves and its second year rocketing to two metres of spiny, ridged stems. In midsummer each stem tip carries an oval, bristly flower head, the pale flowers opening in a banded ring that works its way up the head over several weeks.

The dried heads hold their shape all winter, which has made the teasels a fixture of dried-flower work since the wool trade used their cousins to raise the nap of cloth. It wants open, sunny, well-drained ground and seeds itself freely once established. The leaves are rough to the touch and the stems carry short downward prickles, so gloves are worth wearing when the plant is handled at all.

Science & Biotechnology

The genus has interested botanists for the heads’ staged flowering, a built-in sequence that spreads pollination over weeks, and for the water-holding basins formed where opposite leaves join the stem, tiny pools that trap and digest insects weakly enough to count the genus among the protocarnivorous plants.

In pharmacology the genus is famous through Xu Duan, the drug root of <em>Dipsacus asper</em>, whose iridoid glycosides are studied for bone-metabolism effects; this species is a recognised close relative used regionally in the same direction. The banded opening of the flowers, a ring at a time over several days, has been documented in pollination studies as a mechanism that keeps a single head attractive to insects for over a week. The leaf-junction water pools have been tested experimentally, with small insects drowned in them and nutrients absorbed, a graded stage on the road to full carnivory that makes the genus a textbook case.

Uses & Benefits

In the garden it is architecture: two metres of spiny summer presence, then a winter of bronze heads that catch frost and hold the birds’ attention. Flower heads feed bees through their long banded bloom, and finches take the seed heads when they stand.

The dried heads fill arrangements and winter borders, and the root has a long record in the traditional practice of the East as a tendon-and-bone herb, though the commercial drug comes from its mountain relative. Florists cut the stems just as the first ring opens and dry them upside down in a dark shed, which preserves both the shape and the pale colour through the winter. Finches and buntings take the seed from standing heads through winter, and the spiny heads also give late-season shelter to small birds hunting the margins.

Growing from Seed

Sow fresh seed in spring or early summer on the surface of a loose compost, covering barely, and keep moist; the first year is all rosette, so treat it as a patience crop.

Plant the rosettes out a foot apart in full sun, and the following summer the stems rise. Let a few heads stand and shed seed to keep a supply, but deadhead the rest, because a single plant can leave hundreds of recruits. The rosette stage dislikes competition, so keep a hand’s width of bare soil around each plant through the first summer, and the second-year stems will pay for the weeding. Where the ground is rich the biennial may flower in its first autumn, though the classic two-year rhythm is the norm on ordinary garden soil.

Our Take

A biennial that spends a year looking plain and then pays it all back with spires, bees and a winter of bronze heads. Sun, drainage and one seed year is the whole commitment.

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