Dipsacus sylvestris Huds. - Teasel
Family - Dipsacaceae
Stems - To +2m tall, from
stout taproot, erect, herbaceous, carinate, with flattened straight prickles,
branching above or simple.
Leaves - Opposite, linear-lanceolate,
sessile, to +20cm long, +6cm broad, glabrous, with prickles on midrib (below)
and on margins, acute. often basally connate. Basal leaves often drying
by anthesis.
Inflorescence - Dense ovoid
pedunculate cluster of many flowers terminating stem. Cluster subtended
by ascending bracts to +/-10cm long. Bracts with straight prickles. Each
flower subtended and cupped by an awn tipped chaff to +2cm long. Chaff
pubescent, green to purple at apex.
Flowers - Corolla lavender
at apex, whitish near base, to +1cm long, 4-lobed, dense pubescent on tube
portion. Stamens 4, alternating with corolla lobes, adnate near apex of
corolla tube, exserted. Filaments glabrous. Style well exserted, glabrous,
white. Calyx tubular, 4-angled, 4-lobed, green. Achenes to +5mm long.
Flowering - June - October.
Habitat - Fields, thickets, pastures, waste ground, open woods, roadsides, railroads.
Origin - Native to Europe.
Other info. - This species
and the closely related D. laciniatus L. are noxious
weeds in Missouri and throughout their range in the U.S.. The fruiting
heads produce many small achenes and the plant is easily spread and hard
to exterminate.
A better synonym is D. fullonum L.
Photographs taken off Highway 77 near Partensburg, West Virginia, 7-20-02.
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