Lesser burdock |
Habit,
flowers, upper leaf surface, underside of the leaf and
cross
section of
the petiole
| Arctium minus Hill (Bernh.): | |
| Blooming period: | July–Oktober |
| Height: | 50–300 cm |
| Flowers: | in heads, Ø of the heads
15–28
mm, stamens:
5, styles: 1 |
| Ray florets: | missing |
| Disc florets: | pink to purple |
| Calyx: | transformed into a pappus |
| Stem leaves: | alternate, stalked, egg-shaped, entire to coarsely toothed, undulated |
| Basal leaves: | up to 70 cm long, petiole hollow, heart-shaped, entire to coarsely toothed, undulated |
Plant biennial, herbaceous, with a deep, strong, up to 5 cm thick taproot.
Stem erect, grooved, hollow, rough, sometimes arachnoid, branched. Branches spreading.
Stem leaves alternate, losing upwards in size, stalked, lamina ovate, base truncate or cordate, entire, coarsely toothed or weakly lobed, undulate, grey tomentose underneath.
Basal leaves large, long-petiolate, petiole hollow, leaf blade lobed, cordate, entire, coarsely toothed or slightly undulated, grey tomentose underneath.
Flower heads terminally or laterally in long racemose, paniculate or spiciform inflorescences. Sessile or stalked, up to 40 mm long. Receptacle flat and densely bristly. Bristles filiform, white, 5–9 mm long.
The linear to linear-lanceolate phyllaries are arranged imbricated in numerous rows. They have an inwardly directed, short hook at the top, the margins are toothed very finely. The tips of the outer phyllaries are spreading, those of the inner ones are upright and reddish. Involucre spherical, sometimes arachnoid, at the fruiting time largely closed.
The flower head consists solely of 40 tubular florets which are pink to purple or rarely white, 16–21 mm long, hermaphrodite and 5-dentate. They possess purple stamens and white pistils, florets at the base without chaffy scales.
After self or insect pollination are formed 5–8 mm long, rough, dark brown, sometimes mottled, oblong, triangular, slightly ribbed nut fruits (achenes), at the top with a few circles of about 2 mm long, barbellate, white to yellowish bristles.
Arctium minus may form bastards with A. tomentosum, A. lappa and A. nemorosum.
| Floral formula: |
| * K=pappus [C(5) A5(connate)] G(2) inferior |
Occurrence:
On
path
and roadsides, ruderal areas, fallow land, forest
edges. Prefers
bright, slightly warm, slightly damp, decalcified and very
nitrogen-rich locations.
Diustribution:
Originally
Eurasia, introduced in Australia and the Americas.