Amsonia tabernaemontana Walt. - Blue Star

Amsonia tabernaemontana plant

Family - Apocynaceae

Stems - To +1m tall, erect, simple or branching near apex, glabrous, herbaceous, 4-5mm in diameter, from thick woody roots.

Amsonia tabernaemontana stem

Leaves - Alternate, short-petiolate, (the petioles to -1cm long or absent on some lower leaves), lanceolate, acuminate at apex, to +3cm broad, +8cm long, slightly glaucous below, dull green above, glabrous. Margin ciliate.

Amsonia leaves

Inflorescence - Terminal, loose cymes, to +/-8cm tall.

Flowers - Corolla light blue-purple, tubular, 5-lobed, glabrous at the base externally, with at least some pubescence near the apex externally, with dense multicellular intertwined hairs at summit internally, with dense retrorse pubescence below point of filament attachment. Tube 8mm long, more broad near apex. Lobes to 1cm long, 3mm broad. Stamens 5, alternating with corolla lobes, adnate to corolla tube near apex. Filaments .5mm long. Anthers yellow-orange, .8mm long, -.5mm broad. Style glabrous, 4.5mm long. Stigma capitate, winged at base. Carpels 2, seeds many. Calyx tube to 1mm long, 5-lobed, glabrous. Lobes subequal, .5 to 1.5mm long, slightly scarious margined. Follicles to +10cm long.

Amsonia tabernaemontana flowers

Amsonia tabernaemontana flower

Amsonia tabernaemontana calyxCalyx and corolla tube.

Flowering - April - May.

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

Origin - Native to U.S.

Other info. - This striking species can be found mainly in the southern half of Missouri and aslo in a handful of counties around the St. Louis area. 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.
Steyermark broke the species up into 3 different varieties based on leaf shape and inflorescence shape. These varieties will not be discussed here.

Photographs taken off County Road 40 in the Lowndes Wildlife Management Area, Lowndes County, AL., 4-9-05.


Back