Sisymbrium loeselii L.

Sisymbrium loeselii plant

Family - Brassicaceae

Stems - To +1.2m tall, erect, herbaceous, from large taproot, typically branching above, pilose to hirsute.

Leaves - Alternate, lyrate-pinnatifid, reduced upward, pilose to hirsute, acute at apex. Lower leaves to 15cm long, 6cm broad. Lobes with coarse irregular teeth. terminal lobes of upper leaves typically hastate and truncate at base.

Sisymbrium loeselii leavesUpper and lower leaves respectively.

Inflorescence - Dense terminal racemes, greatly elongating in fruit to +30cm long (tall). Pedicels to 8mm long in flower, slightly longer in fruit, thin (-1mm in diameter), glabrous.

Flowers - Petals 4, free, clawed, yellow, glabrous. Claw to 3mm long. Limb to 3mm long and broad, rounded at apex. Stamens 6, 4 longer and 2 shorter, erect. Filaments to 3.5mm long, glabrous. Anthers yellow, -1mm long. Ovary green, terete, 3mm long. Stigma capitate. Style very short. Sepals 4, yellow, spreading, glabrous, linear to linear-oblong, free, 3.5mm long, 1.4mm broad, with small protrusion at apex and a single pilose hair arising from protrusion. Fruit a teret silique to 3cm long, 1mm in diameter, glabrous, with beak of persistent stigma and style.

Sisymbrium loeselii sepalsSepals.

Sisymbrium loeselii flowersFlowers.

Flowering - Late April - October.

Habitat - Disturbed sites, waste ground, thickets, roadsides, railroads.

Origin - Native to Europe.

Other info. - Uncommon just 30 years ago, this plant is spreading quite quickly throughout the state. The bright straight racemes are easy to pick out along roadsides and railroads but are easily confused with other showy members of the family like Barbarea vulgaris. A closer look quickly differentiates the two.

Photographs taken off Route 118, Holt County, MO., 5-3-00.


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