Penstemon tubaeflorus Nutt.

Penstemon tubaeflorus plant

Family - Scrophulariaceae

Stems - To +1m tall, erect, simple, herbaceous, glabrous, from thick caudex.

Leaves - Opposite, sessile and partially clasping, entire or with few shallow teeth, glabrous, typically ovate below and lanceolate to oblong above, to 13cm long, +/-3cm broad, acute. Most leaves are on the lower half of the stem, those by the inflorescence reduced to bracts.

Penstemon tubaeflorus leavesLower to upper leaves respectively.

Inflorescence - Long terminal thryse to -40cm long(tall). Cymes of flowers in +/-6 verticillasters. Cymes with +/-6 flowers. Each cyme subtended by pair of foliaceous bracts. Peduncles and pedicels with gland tipped pubescence(typically not dense). Pedicels to 1cm long. Cymes with axes erect and remaining mostly parallel to axis of thryse.

Flowers - Corolla pure white, weakly funnelform with the tube staying fairly narrow, 2cm long, -2cm broad at apex, glandular pubescent internally and externally, zygomorphic, 5-lobed. Lobes obtuse to rounded. Stamens 4, adnate to lower half of corolla tube, included. Filaments to 1.5cm long, white, glabrous. Anthers blackish, 1.7mm long. Staminode with sparse glandular pubescence and with compressed yellow-brown pubescence on apex (dorsally). Style 1cm long, glabrous, white. Ovary glabrous, green, 3mm long, 2mm in diameter, 2-locular. Placentation axile. Sepals 5, 5mm long, 2.2mm broad, glandular pubescent externally, glabrous internally, lance-ovate, acute to acuminate, with slightly scarious margins. Capsules to 1cm long, many seeded.

Penstemon tubaeflorus corollaCorolla.

Penstemon tubaeflorus calyxCalyx and corolla tube.

Flowering - May - June.

Habitat - Prairies, glades, open woods.

Origin - Native to U.S.

Other info. - At first glance this species may resemble the very common P. digitalis Nutt. but the two are different in several ways. You can find P. digitalis on this same section of this website to compare the two.
P. tubaeflorus is a very showy plant with densely flowered inflorescences. It is fairly common in the south-western corner of Missouri, but is scattered throughout the rest of the state. The inflorescence of the plant is very cylindrical and the stem below it typically appears almost naked. The peduncles and pedicels can vary in the amount of pubescence present.

Photographs taken at the Kansas City Zoo, 6-27-00, and at Prairie State Park, Barton County, MO., 6-23-00.


Back