Species

• Carolina phlox, thickleaf phlox, also summer phlox and giant phlox
• Phlox carolina L.
• Polemoniaceae, the phlox family
• Confidence high for Phlox carolina. The genus is certain. The species sits inside the genuinely difficult carolina / glaberrima / maculata complex, but after close examination every alternative in and around that complex is excluded by a concrete observed character (see the look-alike table and the confidence note below). The load-bearing observation is the densely hairy (villous) calyx, verified under high-magnification crops.

Evidence (tied to the photos)

• Flower structure (IMG_4996, IMG_4999): 5 fused petals forming a salverform corolla, a long slender tube flaring to a flat face, with a small darker or paler eye and a hint of yellow at the throat. Textbook Phlox.
• Petal lobes (IMG_4999 close-up): broad, rounded, and entire, not notched or cleft. That rules out the spring woodland phloxes (P. divaricata, P. stolonifera) and the often-notched P. pilosa.
• Leaves (IMG_4997): narrow, lanceolate, opposite, sessile, entire-margined, tapering to an acuminate tip, roughly ≤2 cm wide. Lateral veins are obscure, with no strong looping submarginal collecting vein. The surface is matte and finely downy rather than glossy.
• Stem (IMG_4996 lower-stem crop, IMG_4997 node): green, unspotted, finely pubescent. No purple speckling.
• Calyx and inflorescence (IMG_4998): calyx lobes long, awl-shaped (subulate), densely hairy, with conspicuously pubescent pedicels and inflorescence axis. Several spent brown flower heads are present, so the plant has been in bloom a while.
• Color and habit: lilac-purple flowers in a rounded to shortly cylindrical terminal cluster on an upright leafy stem. A tall phlox, not a creeping one.

Look-alikes ruled out

The chain: obscure leaf venation on narrow leaves excludes the paniculata group. A hairy, unspotted stem with a rounded inflorescence excludes maculata. The densely villous calyx excludes the glabrous glaberrima, the nearest habitat match. Moist cove, mid-July bloom, tall habit, and entire petals exclude pilosa, amoena, and the spring woodland phloxes. What's left is P. carolina.

Habitat check

Good fit, with one nuance. Phlox carolina is "frequently found in the southern mountain regions" of NC, which includes Polk County and the Blue Ridge escarpment, in forests, woodland borders, and clearings on acidic soils. Weakley's Flora rates it FACU (facultative upland), so it isn't a wetland obligate, but it readily occupies moist cove-forest ground, and a low valley ~50 m from a stream is comfortably within its range. The wetter-loving P. glaberrima would be a slightly better moisture match, which is why the villous-calyx character rather than habitat is what settles the ID.

Confidence note — what this rests on and what would change it

• Load-bearing observation: the densely villous calyx, plus downy stem and leaves. That is what excludes the glabrous P. glaberrima, the only serious alternative left after venation and stem characters. The pubescence was checked on high-magnification crops and is unambiguous, so it's solid.
• Would raise it to near-certain: a look at the lower stem for faint purple speckling, a final check against maculata; a ripe seed capsule for seed and valve characters; or a clear read of sepal width and midrib, where broad and weak means carolina and narrow and strong means glaberrima.
• Residual caveat: the carolina/glaberrima/maculata complex intergrades and has been split and lumped repeatedly. A herbarium determination could assign it to a particular variety of P. carolina, say var. carolina against var. angusta, but that doesn't change the species-level call.

Seed propagation

• Maturity window and the mid-July problem: Phlox carolina blooms May–July and can rebloom into fall. Seed capsules ripen roughly 4–6 weeks after each flower opens. In these photos the plant is in full flower, with only a handful of spent heads, so mature seed is largely not yet available in mid-July. Most of what I collected is flowers rather than ripe capsules. Treat any seed collected now as immature and low-viability and don't count on it.
• When capsules do ripen: phlox capsules dehisce explosively and fling the seed. To collect, tie a fine mesh or organza bag over browning capsules and gather seed as the capsules dry, typically Aug–Sep for the earliest flowers.
• Cleaning: let capsules finish drying in a paper bag and the seed pops free. Winnow out the chaff.
• Stratification: sow fresh in fall outdoors, or give ~4–8 weeks cold-moist stratification (seed in damp medium, 34–40 °F / ~2–4 °C) before a spring sow.
• Germination: after stratification, warm (65–70 °F) with light. Expect roughly 2–3 weeks to emerge, though phlox germination is often uneven.

Vegetative propagation — the realistic route this time

I collected leafy flowering stems rather than ripe seed, so softwood stem cuttings are the best bet, and mid-July is squarely inside the recommended May–July softwood window for this species.

• Softwood or basal stem cuttings, to do now:
  1. Recut each stem to 4–6 in, cutting just below a leaf node. Remove the flower head and the lower pairs of leaves, and root a non-flowering section if one is available.
  2. Dip the base in ~0.1% (1000 ppm) IBA rooting hormone. Optional, but it speeds things up.
  3. Stick in a fast-draining, humid medium of peat, coarse sand, and perlite, kept moist, warm, and bright but out of direct sun, in a covered tray or humidity dome.
  4. Expect roots in ~2–4 weeks, then pot on once well rooted.
  • The collected stems have been handled and are wilting, so act fast and recut the bases, ideally under water, before sticking.
• Root cuttings: a classic phlox method, but taken from dormant roots in fall or winter. Not applicable to what I collected.
• Division: reliable, but it needs the whole crown, so not an option from cut stems.

Grow-out in the NC Piedmont

• Hardiness: USDA zones ~5–9. The Piedmont is well within range.
• Light: full sun to part shade. Light afternoon shade helps in hotter, drier Piedmont summers and keeps it closer to its cove-forest origins.
• Soil and moisture: rich, moist, well-drained, acidic soil. It came from a wet streamside cove and has low drought tolerance, so give it consistent moisture. Amend heavy Piedmont clay with organic matter and avoid a baking, dry site.
• Phlox carolina is notably more powdery-mildew resistant than garden phlox (P. paniculata), which is what the famous white cultivar 'Miss Lingard' is prized for, so it's a lower-maintenance choice for humid NC. Fragrant, and it attracts butterflies and hummingbirds. Give it decent air circulation anyway.

Next step

Root the collected stems as softwood cuttings today. Recut each to ~5 in below a node, under water if possible, strip the flowers and lower leaves, dip in rooting hormone, and stick them in a moist peat/sand/perlite mix under a humidity dome in bright indirect light. Don't rely on seed from this mid-July collection; the capsules aren't ripe yet. If I can get back to the site in late Aug–Sep, bag a few browning seed heads to catch mature seed as a backup.

Sources

• NC State Extension — Phlox carolina (Carolina / Thick-leaf Phlox)
• NC State Extension — Phlox maculata (Meadow / Spotted Phlox)
• NC State Extension — Phlox glaberrima (Smooth / Marsh Phlox)
• NC State Extension — Phlox paniculata (Garden / Tall Phlox)
• Lady Bird Johnson Wildflower Center — Phlox carolina
• Flora of the Southeastern US (Weakley) — Phlox key
• Flora of the Southeastern US — Phlox carolina taxon detail
• Flora of the Southeastern US — Phlox glaberrima taxon detail
• NameThatPlant.net — Phlox carolina (Carolinas/SE)
• Native Plant Trust Go Botany — Phlox dichotomous key
• Clemson HGIC — Phlox
• RHS — Phlox carolina 'Miss Lingard'
• Plant Addicts — Propagating Phlox