Vascular Plants of Williamson County

Sabatia campestris [Gentianaceae]
prairie rose–gentian, false–gentian

Sabatia campestris Nutt., prairie rose–gentian, false–gentian. Annual, taprooted, ± not rosetted, 1–stemmed at base, canopy of ascending branches each with a terminal inflorescence, erect, in range 5—20 cm tall; shoots with several short–lived basal leaves and with persistent cauline leaves, glabrous and totally lacking glandular hairs; latex cloudy.


Stems 4–sided and 4–ridged (short–winged), 0.4—2.5 mm diameter, on each internode 2 ridges descending from each leaf and terminating at next node, tough, light green, principal lower stem forming periderm.


Leaves opposite decussate (rarely on diminutive plant the earliest, small leaves in whorls of 3), simple (1—2 lobes near midblade), sessile, without stipules; blade ovate to elliptic, 3.5—25 × 2—7 mm (unlobed), dull, entire, acute to obtuse or rounded at tip, pinnately veined with midrib raised on lower surface.


Inflorescence cyme, terminal, open, several–flowered, with only 1 branch at each node, bracteate, glabrous; bracts subtending cymes and bractlets subtending flowers in pairs, leaflike, decreasing upward; peduncle ascending, stemlike; pedicel suberect to ascending, stemlike and 4–ridged but 5–ridged approaching flower, at anthesis to 20 mm long increasing to 2× in fruit.


Flower bisexual, radial, in range (11—)22—33 mm across; calyx 5—6(—7)–lobed; tube vase–shaped, 1.5—5.5 × 1.2—4 mm, conspicuously 5–ridged with ridges green and faces membranous and later stressed, 10–veined, ridges descending from sinuses and upper pedicel; lobes appressed to corolla lobes, narrowly triangular, 3—9 mm long, 1.2—2.5 mm wide and (1–)3–veined at base, green, minutely bumpy on margins, acute at tip, persistent; corolla (4—)5(—6)–lobed, short trumpet–shaped with conspicuous horizontal lobes, lobes twisted in bud; tube membranous and vase–shaped (conforming to ovary), 2—5 mm long, to 3 mm wide at orifice, colorless, delicate and stretched with ovary expansion, 10–ribbed above with principal veins beneath each calyx lobe; throat short; lobes overlapping at base, broadly obovate to oblong, 6.8—16 × 3.5—10.5 mm, in range dark rose (dark pink), the white area and bright greenish yellow arms of adjacent lobes and upper throat forming a pentagonal (4—6) center with points at midlobes or creating a pentafoil, arms to 4 mm long, paler and somewhat glossy on lower surface, (3–)5–veined at base; stamens (4—)5(—6), fused to base of corolla throat at sinuses alternate with corolla lobes, exserted; filaments 2—4.2 mm long, white and rose above midpoint, glabrous; anthers basifixed, dithecal tapered to tip , (1.5—)2.2—4 mm, bright yellow, longitudinally dehiscent not tightly helically twisted after dehiscence; pollen yellow; pistil 1, mostly 12(—16) mm long (rarely 2 mm long without a long style and apparently sterile), exserted 1—2 mm above stamens; ovary superior, obovoid, to 3.5 × 2 mm, green, glabrous, 1–chambered with 4 placentae intruding with numerous ovules; style mostly 8.5—12 mm long, 2–branched ca. 3 mm from base, white from base to green at fork, the branches narrowly oblong twisted together, green, when twisted inrolled and appearing channeled, papillate on upper (inner) surface.


Fruit capsule, septicidal, dehiscent by 2 valves, many–seeded, subspheroid, ca. 5 × 4.5 mm; at maturity except top concealed by calyx tube and spreading lobes, with corolla tube stretched and papery on surface and with ascending dry corolla lobes and often dry filaments.


Seed roundish to D–shaped, 0.3—0.35 mm long, brown, conspicuously netlike.

A. C. Gibson