Linum sulcatum Riddell - Yellow Flax

Linum sulcatum plant

Family - Linaceae

Stems - To +/-60cm tall, erect, herbaceous, from a taproot, ribbed from decurrent leaf tissue, glabrous, glandular (use lens to see), mostly simple but branching near apex, purplish at base, single or multiple from base.

Leaves - Alternate, sessile, linear-oblong, entire, acuminate, to 2cm long, +2mm broad, with single midrib, glabrous, glandular (use lens to see), with pair of opposing blackish glands at leaf base.

Linum sulcatum leaves

Linum sulcatum glandsGlands at the base of the leaf.

Inflorescence - Terminal and axillary loose panicles or racemes. Each flower subtended by a foliaceous bract. Bracts glandular-serrulate. Pedicels glabrous, 2-3mm in flower, slightly elongating in fruit to 4-5mm.

Flowers - Corolla yellow, +1cm broad, 7-8mm long. Petals 5, glabrous externally, pubescent near base internally, rounded at apex, with short basal retrorse lobes (lobes acute and triangular), connate basally for 1-2mm. Stamens 5, erect. Filaments scarious, compressed and united at base into short tube under the ovary, glabrous, 4mm long, slightly yellowish near the apex. Styles 5, 3mm long, united at base, glabrous, whitish-yellow. Ovary superior, green, 5-locular, (1-2 ovules per locule), glabrous, globose-ovoid, 1.5mm in diameter. Sepals 5, ovate-lanceolate, scarious but with a green midrib, glandular-serrulate, glabrous, to 4mm long, 1.5mm broad, acuminate, persistent in fruit. Capsule globose, glabrous, 3mm in diameter, 5-valved, dehiscing into 5, 2-parted segments.

Linum sulcatum calyx

Linum sulcatum flower

Flowering - May - September.

Habitat - Glades, prairies, sometimes in open woods.

Origin - Native to U.S.

Other info. - This little plant is inconspicuous when not in flower but is still easy to identify because of the pair of opposing, blackish glands at the base of each leaf. The plant is common throughout most of Missouri except in the extreme southeastern and northwestern corners of the state.

Photographs taken at the Peck Ranch Wildlife Refuge, Reynolds County, MO., 7-7-01, and at Busiek State Forest, MO., 6-17-05.


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