Amsonia tabernaemontana Walt.

Blue Star

Amsonia tabernaemontana plant

Family - Apocynaceae

Habit - Perennial forb, sometimes woody near base.

Stems - Ascending to erect, to 1.1 m, usually multiple from base, sometimes branching near tips, with milky sap, glabrous.

Amsonia tabernaemontana stemStem and node.

Leaves - Alternate, short-petiolate, (becoming sessile near base of plant), simple, entire. Petioles to 1 cm. Blades lanceolate to ovate, sharply pointed, 6-15 cm long, 2-5 cm wide, dull green on upper surface, slightly glaucous below, mostly glabrous. Margin ciliate.

Amsonia leavesLeaves.

Amsonia tabernaemontana leaf2Leaf abaxial.

Amsonia tabernaemontana leaves2Leaves not shiny.

Inflorescence - Terminal clusters, 7-12 cm long at flowering, positioned near the leaf tops. Flower stalks 2-7 mm long.

Amsonia tabernaemontana inflorescenceInflorescence.

Flowers - Calyces 5-lobed, the lobes triangular, the tube to 1 mm long, glabrous. Corollas densely hairy internally, sparsely to moderately hairy toward the tip externally, the tube 7-8 mm long, about 1.5 mm wide at base, the throat 2.5-3.5 mm wide, the lobes 5-8 mm long, 1.2-2.0 mm wide, light blue. Stamens 5, alternating with corolla lobes, adnate to corolla tube near apex. Anthers yellow-orange. Style glabrous, 4.5mm long. Stigma capitate, winged at base. Carpels 2, seeds many.

Amsonia tabernaemontana calyx2Calyces.

Amsonia tabernaemontana flowerCorolla.

Amsonia tabernaemontana flowers2

Fruits - Slender follicles to 12 cm long, terete, many seeded, glabrous, erect at maturity, positioned among the leaves, not constricted between the seeds. Seeds 8-10 mm long, the surface usually with low, corky ridges and tubercles.

Amsonia tabernaemontana fruitsFruits.

Flowering - April - May.

Habitat - Open woods, thickets, slopes, ravines, roadsides, railroads.

Origin - Native to U.S.

Other info. - This striking species can be found in scattered locations in the southern half of Missouri and also in a handful of counties around the St. Louis area. It ranges throughout most of the southeastern U.S. The plant is easy to identify becasue of its many blue flowers and broad, pale leaves. This species also bleeds a milky sap when injured. It is very similar to Amsonia illustris, but unlike that species has erect fruits and leaves which are not glossy.

The species has been subdivided into varieties, two of which are currently recognized in Missouri. Variety salicifolia has relatively narrow leaves, to 3 cm wide, and is the most common variety in the state. Variety tabernaemontana has wider (ovate) leaves. The natural ranges of these forms in Missouri have been obscured by escapes from ornamental cultivation and by habitat restoration plantings.

Photographs taken off County Road 40 in the Lowndes Wildlife Management Area, Lowndes County, AL., 4-9-05 (DETenaglia); also at Duck Creek Conservation Area, Bollinger County, MO, 5-18-2014 (SRTurner).


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