Phlox paniculata L.

Perennial Phlox

Phlox paniculata plant

© DETenaglia

Family - Polemoniaceae

Habit - Perennial forb with short, thick rhizomes.

Stem - Ascending or erect, to 1.2 m, often 3-7 from base, with 20-35 nodes, glabrous toward the base, grading to sparsely to densely pubescent above the midpoint with short, curved, usually nonglandular hairs, sometimes with red streaks.

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Stem and node near base.
© SRTurner

Leaves - Opposite (the uppermost sometimes subopposite), simple, entire, sessile or nearly so. Blades narrowly elliptic to oblong-lanceolate, angled or more commonly tapered to a sharply pointed tip, variously angled or tapered at the base, the uppermost sometimes ovate, those of the largest leaves 9-14 cm long and 20-40 mm wide, the upper surface usually glabrous, the undersurface glabrous or less commonly sparsely short-hairy, the margins short-hairy, the secondary veins forming closed loops.

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Stem and leaves.
© SRTurner

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Leaf adaxial.
© SRTurner

Phlox_paniculata_leaf2.jpg

Leaf abaxial.

Note the distinctive looping pattern of the lateral venation.
© SRTurner

Inflorescences - Panicles with usually 35 to more than 200 flowers, the aggregate usually broad, domed to hemispheric or pyramidal, occasionally narrower and appearing somewhat racemelike.

Phlox_paniculata_inflorescence.jpg

Inflorescence.
© SRTurner

Flowers - Flower stalks 2-8 mm. Calyces 6-10 mm long, the lobes slender, tapered evenly to sharply pointed tips, glabrous or pubescent with short, nonglandular hairs. Corollas trumpet-shaped, bright pink to light pinkish purple or purple, the tube 18-25 mm long, sparsely to densely hairy externally, the lobes 6-12 mm long and 4-11 mm wide, obovate to broadly obovate, rounded at the tips, occasionally with a very shallow apical notch. Stamens with the filaments 15-21 mm long, the anthers positioned near the stigma and near the mouth of the tube (occasionally 1-3 slightly exserted). Style 12-24 mm long, the stigmas 0.8-1.3 mm long.

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Calyces.
© SRTurner

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Corolla tubes.

Pubescent.
© SRTurner

Phlox_paniculata_corollas.jpg

Corollas.

Uppermost anthers positioned near mouth of corolla tube.
© SRTurner

Fruits - Capsules with 1-3 seeds.

Flowering - June - September.

Habitat - Forests, streambanks, fens, bluff bases, roadsides, shaded disturbed areas.

Origin - Native to the U.S.

Lookalikes - Other species of Phlox, of which there are several.

Other info. - Of the species of Phlox which occur in Missouri, this is the showiest and the one most often cultivated. Within the state it is found mainly south of the Missouri River. Its North American distribution mainly extends from Missouri northward and eastward into New England and also Canada. More northern populations are considered introduced or escapes from cultivation.

Many species of Phlox can look similar, with showy pink to purple or blue, trumpet-shaped flowers and opposite leaves. Differentiation is based on several factors, including the position of the anthers in the corolla tube, hairiness of the corolla tube, leaf shape and venation pattern, and shape of the inflorescence. The plant is a popular garden subject and many cultivars have been developed. These can have flower colors ranging from white to deep purple, and location preferences ranging from shade to full sun.

The genus name Phlox is derived from a Greek term for a flame, referring to the bright flower colors.

Photographs taken along Logan Creek, Reynolds County, MO., 7-17-03 (DETenaglia); also at Indian Camp Creek Park, St. Charles County, MO, 10-24-2016, and Shaw Nature Reserve, Franklin County, MO, 07-20-2017 (SRTurner).



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