Liatris pycnostachya Michx.



CC = 6
CW = 0
MOC = 67

© DETenaglia

Family - Asteraceae/Eupatorieae

Habit - Perennial forb from a globose corm.

Stems - To -2m tall, glabrous to hirsute (at least above), erect, typically simple, striate to carinate, from thick roots herbaceous.

Liatris_pycnostachya_stem.jpg Glabrous stem.

© DETenaglia

Leaves - Alternate, dense, linear, entire, punctate, +/-5mm wide, to +20cm long, reduced upward, sessile, glabrous to pubescent or slightly scabrous, very numerous. Basal leaves to -40cm long.

Inflorescence - Dense terminal spike to 40cm tall. Flower heads sessile, usually subtended by single foliaceous bract. Axis pubescent to hirsute.

Liatris_pycnostachya_inflorescence.jpg Inflorescence.

© SRTurner

Involucre - To 1cm long(tall), 4-5mm in diameter, cylindric. Phyllaries to 7mm long, +/-2.5mm broad, green below fading to red above, mostly glabrous, punctate, with ciliate margins, tips recurved, acuminate. Flower heads with +/-7 flowers.

Liatris_pycnostachya_involucre.jpg Involucre.

© DETenaglia

Ray flowers - Absent.

Disk flowers - Corolla tube pink, 5-6mm long, glabrous, 5-lobed. Lobes acute, erect to spreading, 2mm long, glabrous. Stamens 5, adnate about 1/3 to 1/2 way up tube, exserted. Anthers connate around style, 3mm long, brownish-purple. Style exserted, bifurcate. Stigma deep pink. Achenes dense pubescent, 3-sided, 3mm long in flower. Pappus of barbed capillary bristles to 5mm long.


© DETenaglia

Flowering - July - October.

Habitat - Prairies, meadows, open ground, glades, railroads, roadsides.

Origin - Native to the U.S.

Lookalikes - L. mucronata.

Other info. - This species is commonly seen in prairie habitats and along roadsides in the Ozarks. It occurs throughout most of Missouri, and also within a band extending from Minnesota southward to the Gulf Coast. The numerous linear leaves and densely flowered spikes are good characteristics for identifying the species. The pappus bristles are simply barbed, in contrast to the plumose pappus bristles found in L. mucronata. Species distinctions within the Liatris genus can be difficult.

Missouri plants have been called var. pycnostachya. A rare phase of the plant with white flowers has been called fo. hubrighti. All the plants in this genus are gaining popularity in cultivation due to the increased interest in butterfly and native landscape gardening.

Photographs taken at Taum Sauk Mountain, MO., 7-28-03 (DETenaglia); also at Weldon Spring Conservation Area, St. Charles County, MO, 7-27-2009 (SRTurner).