Zeltnera beyrichii (Torrey & A. Gray) G. Mans., rock centaury. Annual, taprooted, not rosetted, several–stemmed at base. with erect to suberect branches from base and a branched, flat–topped terminal inflorescence, in range to 20 cm tall; shoots with only cauline leaves, glabrous.
Stems 4–sided, to 2 mm diameter, narrowly ridged along angles descending for 1 internode from a pair of ledges at node, tough, light green.
Leaves opposite decussate, simple, sessile, without stipules; blade linear, 5—25 × 1.2—2 mm, dull, entire (not inrolled), acute at tip, 1–veined with midrib raised on lower surface.
Inflorescence compound cyme, terminal, 20+–flowered per shoot, open but flowers overlapping at top of canopy, often with 5+ orders of branching, bracteate, glabrous; axes never straight, forking at every node, 4–sided with axes stemlike with 4 ridges; bracts subtending cymes and bractlets subtending flowers in pairs, spreading, leaflike, < 20 × < 1 mm decreasing upward, ≥ internode; bractlet subtending pedicel paired with bract subtending fork, equal, linear, 6—7 × 0.5 mm, < pedicel; pedicel 4–sided and 4–ridged, 6.5—7.5 × 0.6 mm increasing in fruit.
Flower bisexual, radial, in range ca. 24 mm across; calyx (4—)5–lobed, fused only at base, ca. 10 mm long; lobes subequal, appressed to corolla tube, acuminate–linear and keeled, 9—10.5 mm long increasing in fruit, green, glabrous, adherent to corolla tube, persistent; corolla (4—)5–lobed, trumpet–shaped (salverform), exserted 3—3.5 mm above calyx, white in bud; tube cylindric, white, with fine veins, delicate and stretched with ovary expansion, persistent; throat broadly funnel–shaped, ± 2 mm long, 0.8 mm wide at base, ca. 3 mm wide and white at orifice; lobes widely spreading, narrowly ovate, ca. 12 × 4.5 mm, in range rose or pink to pale pink (white) and lighter on lower surface, throat + lobes forming white pentagonal pattern below rose or pink, entire, acute at tip, glabrous; stamens (4—)5, fused to base of corolla throat (at level of top of ovary), alternate with corolla lobes, exserted; filaments 9—10 mm long, decurrent portion yellowish within tube, free portion yellowish at base but white above, channeled to midpoint, glabrous; anthers versatile, dithecal, 4.5—5 mm long with short appendage at tip prior to dehiscing, light yellow, longitudinally dehiscent becoming tightly helical (720°) and much shorter after dehiscing; pollen light yellow; pistil 1, 24—26 mm long, exserted 1 mm > stamens; ovary superior, narrowly lanceoloid, 7—7.5 × 1 mm, glossy green but mottled, 1–chambered and longitudinally grooved over each placenta, the 2 placenta intruding with numerous ovules; style straight and erect, thin, channeled approaching stigmas; stigmas formed as 2 short, broad lobes on fan–shaped, floshy top of style, light yellow aging darker, papillate on upper (inner) surface.
Fruit capsule, septicidal, dehiscent by 2 valves, many–seeded, scarious, narrowly fusiform–cylindric, 10—12 × 2—2.5 mm, dehiscing most of its length, tips of valves straight.
Seed D–shaped, 0.4 × 0.3 mm, dark brown, conspicuously netlike.
A. C. Gibson