Phlox drummondii Hooker subsp. drummondii, Drummond’s phlox, annual phlox. Annual, taprooted, 1—several–stemmed at base, not rosetted, erect, in range to 29 cm tall; shoots with only cauline leaves, glandular–hairy
Stems cylindric, to 3 mm diameter, tough, green aging tannish.
Leaves helically alternate (opposite at the lowest node or nodes), simple and sessile, without stipules; blade lanceolate or elliptic to narrowly ovate or narrowly obovate, < 10—30 × 5—8+ mm, ± lobed to subtruncate at base (not clasping), entire, acute at tip, pinnately veined with midrib somewhat raised on lower surface, dull, glandular–hairy.
Inflorescence leafy cyme, terminal, several–flowered, bracteate, green structures glandular–hairy; bractlet subtending pedicel narrowly lanceolate, 7—8 × 1.1—1.4 mm, > pedicel; pedicel at anthesis 3—4 mm long not increasing in fruit, with radiating, long–stalked glandular hairs, the heads colorless to yellowish.
Flower bisexual, radial, 16—18 mm across, unscented; calyx 5–lobed, 6,3—6.8 mm long, conspicuously glandular–hairy with hairs to 1.6 mm long on exposed surfaces; tube narrowly bell–shaped, 3—3.5 × 1.5—1.8 mm, alternating green to lobes and with membranous panels, each 1–veined, membranous panels relaxed later stretched by developing fruit; lobes ascending–spreading from midpoint, acuminate with fine point at tip; corolla 5–lobed, with darker starlike pattern radiating on limbs from throat, variable color in population, persistent if not pollinated; tube + throat slender, to 18 mm long, 1 mm diameter at midpoint, ± striped rose–red to purple red, paler to white approaching limbs; lobes fan–shaped, 8—8.5 × 8—8.5 mm, light to dark rose or pink–purple, paler on lower surface, upper surface minutely papillate; stamens 5, fused to corolla throat at 4—5 different levels, included; filaments decurrent on corolla, free portion threadlike, < 1 mm long (sessile), white; anthers all above level of stigma, dorsifixed, dithecal, ca. 2 mm long, light yellow, longitudinally dehiscent; pollen yellow; nectary disc below ovary, 0.3—0.35 mm tall, dark green; pistil 1, ca. 3 mm long; ovary superior, ovoid, 1 × 0.4 mm, green, 1–chambered with 3 ovules; style 3–branched, lower portion ca. 0.8 mm long, green, the branches ascending, 1..2—1.3 mm long, > stalk, pale green, papillate.
Fruit capsule, dehiscent by 3 valves, 1(—3)–seeded, broadly ellipsoid, ca. 3.5 × 2.5 mm; tannish, calyx tube splitting along papery panels.
Seed hemi–ellipsoid with flat face, ca. 3 × 1.5 mm, brown, rough and wrinkled with finer cellular texture; not mucilaginous when wetted.
A. C. Gibson