1 Sepal lobes with a long (0.5-2.1+ mm long) awn attached at or below their apices.

  2 Sepal awns white.

    3 Sepal awns spinose, in the general plane of the sepal, 0.9-2.0 mm long; plants perennial; [inland provinces of AL, GA, KY, NC, TN, VA, WV]

    3 Sepal awns broadly conical, divergent from the plane of the sepal (angled outwards); plants annual or biennial; [Coastal Plain of LA, TX, and OK].

      4 Stems erect; sepal awns 0.5-0.6 mm long, glabrous; [w. LA, se. OK, south to e. TX]

      4 Stems prostrate; sepal awns 0.3-0.4 mm long, scabrous; [s. TX]

  2 Sepal awns green to brown or yellow.

        5 Leaf apices conspicuously mucronate; leaves elliptic to ovate or spatulate, 1-6 mm wide, 2-4× as long as wide; [Coastal Plain of NC, SC, GA, AL, and FL]

        5 Leaf apices not conspicuously mucronate (if submucronate as in P. lindheimeri, then leaves also linear to filiform), but otherwise obtuse, acute, or minutely cuspidate; leaves linear or subulate, 0.3-1 mm wide, 10-20+× as long as wide; [west of the Mississippi River, or disjunct eastwards in the inland provinces of AL, GA, VA, WV, MD, and DC].

          6 Stems herbaceous; plants annual, biennial, or perennial; [TX].

             7 Stems glabrous to minutely puberulent; terminal flower clusters 0.5-1.5 mm wide, the calyces extending past the subtending bracts; [mainly of limestone soils on the Edwards Plateau and adjacent areas]

             7 Stems strongly hispid or puberulent; terminal flower clusters 3-15 mm wide, the subtending bracts exceeding the calyces; [mainly of Coastal Plain sands in e., se., and s. TX].

               8 Sepal lobe margins yellow and scarious; plants perennial; [s. TX (Brooks, Jim Hogg, Kenedy, Kleberg counties]

               8 Sepal lobe margins white and scarious; plants annual or biennial; [e. and se. TX]

          6 Stems woody, from a tough, dense caudex; plants strongly perennial and long-lived, with old stems apparent; [collectively more widespread, including TX].

                 9 Calyx (not including the awn) 1-3-1.8 mm long, broadly rounded, with no apparent veins

                 9 Calyx (not including the awn) 2.0-2.9 mm long, lanceolate-triangular, with the midvein and 2 lateral veins prominent.

                   10 Sepals densely pubescent; calyx+awn (3.3-) avg. 4.2 (-5.4) long; sepal awns (0.4-) avg. 0.8 (-1.5) mm long, densely pubescent; sepal awns moderately to extremely back-curved; stems and leaves moderately to densely (and uniformly) pubescent; [sw. MO and AR south to e. and c. TX and COA]

                   10 Sepals glabrous; calyx+awn (3.0-) avg. 3.8 (-4.9) mm long; sepal awns (0.2-) avg. 0.6 (-1.1) mm long, glabrous; sepal awns with little or no back-curvature; stems and leaves glabrous to minutely pubescent, the stem hairiness (when present) mainly isolated to near-nodal portions of the stem; [disjunctly scattered east of the Mississippi River, in c. AL, ec. GA, w. VA, e. WV, DC, and sc. & w. MD]

1 Sepal lobes rounded or with a short (< 0.3 mm long) mucro or cusp.

                     11 Sepals petaloid, the tip, margins, or entire sepal whitish; perigynous zone very well developed (mostly equaling or somewhat longer than the sepals); [of the Coastal Plain, from SC southward and westward]; [subgenus Siphonychia].

                       12 Sepals glabrous to the base; plant a cespitose perennial with ascending annual stems; [gulf coastal plain dunes and coastal Pinus elliottii scrubby flatwoods]; flowers borne in distinctly geometric cymes

                          13 Stems minutely gray-puberulent, hypanthium minutely pubescent

                          13 Stems glabrous and often also glaucous, hypanthium glaucous

                       12 Sepals densely pubescent on the basal portion (glabrous above); plant a sprawling, ascending or erect annual OR a sprawling thick tap-rooted perennial (P. discoveryi; the flowers borne in or not borne in distinctly geometric cymes.

                            14 Sepal apices not mucronate, instead broadly rounded or truncate; sepals forming a broadly rounded or dilated hood; CHECK THIS BUT: Pubescent portion of the sepal nearly ½ its length; sepals broadly rounded and hooded; stem glabrous to glabrate, finely retrorse-pubescent, or one side with curly hairs.

                              15 Plants diffuse annuals with slender taproots, the taproots of similar width or only slightly thicker than the primary stem; flowers 1-1.5 mm long; sepal lobes widely obovate (due to broadly distinct apical dilation), flowers appearing more broadly rounded (and obscurely or not strongly 5-angled) due to lack of conspicuously raised marginal costae; [south-central SC s. to FL, w. to AL]

                              15 Plants (often) mat-forming perennials with thick taproots, the taproots much thicker than the primary stem; flowers 1.4-2.2 mm long; sepal lobes oblong; flower bases appearing 5-angled due to conspicuously raised marginal costa; [endemic to eastern and central Florida]

                            14 Sepal apices mucronate; sepals not forming a broadly rounded or dilated hood. Pubescent portion of the sepal <1/3 its length; sepals narrowed toward the apex, with a short tooth or awn; stem uniformly pubescent with retrorse hairs.

                                16 Stem spreading or ascending, the branching unevenly dichotomously, the flowers therefore in diffuse cymes, flowers 1.2-2.2 mm long; glabrous portion of the sepal 0.8 mm long, sepal lobes oblong, the apices broad to nearly truncate (besides the mucro)

                                16 Stem erect, the branching symmetrical and dichotomous, the flowers therefore in weirdly geometric, tight square cymes, flowers 2.3-3.5 mm long; glabrous portion of the sepal > 1.1 mm long, sepal lobes long acuminate and slender, the apices acute to narrowly rounded (besides the mucro)

                     11 Sepals not petaloid, green, sometimes scarious-margined; perigynous zone somewhat shorter than the sepals; [of various provinces, collectively widespread in our area]; [subgenus Paronychia].

                                  17 Leaves with a distinctly ciliate margin; plants prostrate.

                                    18 Plant an annual (-biennial); stems 1-4 dm long, uniformly and minutely recurved-puberulent; flowers 1.25-1.4 mm long, shortly ciliate to nearly glabrous; sepals ca. 1 mm long, oval-oblong, the margin ciliolate; style 0.4-0.5 mm long, bifid; fruit rounded at the top

                                    18 Plant a perennial; stems 2-12 dm long, glabrous or minutely puberulent in longitudinal bands; flowers 1.45-1.55 mm long, more or less glabrous; sepals 1-1.2 mm long, oblong, with a brownish margin; style 0.35-0.4 mm long, the 2 lobes divergent-recurved at maturity; fruit narrowed to the top

                                  17 Leaves entirely glabrous or with a slightly ciliate-serrulate margin; plants erect, suberect, or somewhat prostrate.

                                       19 Flowers 3, 4, or 5-merous, 0.5-0.8 mm long; plants often exhibiting sexual dimorphism or polygamodioecy (male plants more openly branched and trailing; female or hermaphroditic plants more densely matted with shorter, somewhat erect branches); [endemic to sandy lake margins or scrub of Florida].

                                         20 Leaves 0.5-1.5 mm wide; cymes 3-20 mm wide; stem base 1-4.2 mm wide; [endemic to c. FL scrub and similar xeric habitats]

                                         20 Leaves 1.2-3 mm wide; cymes 1.5-4 mm wide; stem base 0.4-1.5 mm wide; [endemic to sandy draw-down zones of lake margins in Washington and Bay counties, FL]

                                       19 Flowers 5-merous, 0.9-1.6 mm long; plants not sexually dimorphic, usually somewhat erect; [c. MS, AL, and GA north and westwards, habitats various].

                                           21 Style elongate, 0.6-0.75 mm long, often bent; anthers 0.25-0.3 mm in diameter; stipular bracts subtending the flowers narrowly lanceolate, ca. 0.5× as long as the flowers

                                           21 Style short, 0.3-0.35 mm long, straight; anthers ca. 0.15 mm in diameter; stipular bracts subtending the flowers lanceolate, from much shorter than to exceeding the flowers.

                                             22 Stems retrorsely puberulent (sometimes sparsely so); sepals leathery, 1-1.2 mm long; leaves oblanceolate, 5-15 mm long, 2-5 mm wide, acute (rarely sub-obtuse to obtuse), firm in texture, dull brownish-green.

                                               23 Stipular bracts subtending the flowers exceeding the flowers (calyx)

                                               23 Stipular bracts subtending the flowers somewhat shorter than the flowers (calyx).

                                                 24 Sepals with a minute cusp or mucro

                                                 24 Sepals with a distinct white awn to 0.2 mm long