ACANTHACEAE

Daniel, Thomas F., García-Morales, Leccinum J. & Mora-Olivo, Arturo, 2021, Taxonomic and Photographic Guide to the Acanthaceae of Tamaulipas, Mexico, Proceedings of the California Academy of Sciences 67 (6), pp. 185-228 : 188-194

KEY TO THE GENERA AND SPECIES OF TAMAULIPAN ACANTHACEAE

1a. Mangrove trees or shrubs with pneumatophores; fruit a leathery and tardily dehiscing/non-explosive capsule with 1 seed...................................................... Avicennia germinans

1b. Herbs, shrubs, or vines, pneumatophores absent; fruit a woody and explosively dehiscent capsule with 2 or more seeds........................................................................ 2

2a. Seeds not borne on hooklike retinacula (retinacula absent or papilliform); plants without cystoliths; anthers 2-thecous............................................................................ 3

2b. Seeds borne on conspicuous hooklike retinacula; plants with cystoliths (or if plants without cystoliths, then anthers 1-thecous); anthers 2-thecous or 1-thecous........................................... 4

3a. Caulescent twining vines; leaves opposite on elongate stems; inflorescence of 1-flowered pedunculate dichasia in leaf axils, peduncles naked; stigma not touch-sensitive; calyx inconspicuous, shallowly 11–17- lobed; capsule with a prominent sterile distal beak longer than the fertile globose base; pollen spiraperturate............................................................... Thunbergia

a. Petioles alate; leaf blades sagittate; corolla orange, throat dark purple, internally glandular; thecae pubescent, at least 1 theca per anther with a prominent basal appendage; capsule 14–23 mm long.................................................................... T. alata

a’. Petioles naked; leaf blades ovate to narrowly ovate-deltate; corolla entirely white (or with throat faintly yellow), throat internally eglandular; thecae glabrous, lacking basal appendages; capsule 22–27 mm long......................................................... T. fragrans

3b. Acaulescent or subcaulescent perennial herbs; leaves in a basal cluster; inflorescence borne on peduncles covered with coriaceous and clasping scales; stigma touch-sensitive; calyx deeply 4-lobed, anterior lobe shallowly 2-parted; capsule without a prominent sterile distal beak (beak, if present, considerably shorter than fertile portion of capsule); pollen 3-colpate...................................... Elytraria

a. Leaves 4. 5–25 mm wide; bracts lanceolate, 6–11 mm long; calyx 6–8 mm long; corolla pinkish to nearly white.......................................................... E. bromoides

a’. Leaves 27–112 mm wide; bracts broadly ovate, 3.8– 5 mm long; calyx 4.5– 5.2 mm long; corolla yellow............................................................... E. macrophylla

4a. Calyx 3-lobed, 32–47 mm long; corolla whitish to greenish cream, lacking colored markings, 55–60 mm long, throat prominently saccate (forming a conspicuous pouch); pollen pantoforate................................................................................ Louteridium tamaulipense

4b. Calyx 4- or 5-lobed, 1–30 mm long; corolla not with the above combination of characters; pollen not pantoforate.......................................................................... 5

5a. Stamens 4, sometimes also with an additional staminode..................................... 6

5b. Stamens 2, sometimes with additional staminodes.......................................... 12

6a. Corolla lemon yellow turning dark blue-purple or blackish on drying; calyx deeply 4-lobed, lobes heteromorphic with outer (anterior and posterior) lobes larger than inner (lateral) lobes; anterior lobe apically 2- cleft.............................................................. Barleria oenotheroides

6b. Corolla variously colored, but when yellow, not turning dark blue-purple or blackish on drying; calyx 5- lobed, lobes homomorphic (or if heteromorphic, then not with lobes as described above), anterior lobe apically entire.......................................................................... 7

7a. Cystoliths absent; anthers 1-thecous; corolla lobes ascending-cochlear in bud; pollen 3-colpate....... 8

7b. Cystoliths present; anthers 2-thecous; corolla lobes contorted (left-contort) in bud; pollen otherwise.. 10

8a. Bracts with 2 submarginal clusters of padlike nectaries (up to 16 per cluster) on abaxial surface; corolla reddish, 30–45 mm long, lateral lobes of lower lip much reduced and appearing attached to upper lip, 0.2– 2.5 mm long, lower-central lobe reflexed or usually recoiled; anther thecae 3–4 mm long.................................................................................. A phelandra scabra

8b. Bracts without submarginal clusters of padlike nectaries on abaxial surface; corolla pink, white to cream (often with greenish tinge), or yellow, 9-20 mm long, lateral lobes of lower lip neither reduced nor appearing attached to upper lip, 3. 5-10 mm long, lower-central lobe not reflexed or recoiled; anther thecae 1.2- 2.3 mm long...................................................................... 9

9a. Caulescent shrubs; leaves opposite or whorled; corolla strongly zygomorphic, white to cream (often with greenish tinge) or yellow, limb not rotate; anthers at least partially exserted from mouth of corolla............................................................................... Holographis

a. Leaves opposite; abaxial surface of bracts and bracteoles glabrous; corolla white to cream (often with greenish tinge), 9-12 mm long, externally glabrous; seeds papillose with both minute and larger rounded papillae................................. H. tamaulipica

a’. Leaves usually whorled (rarely opposite on some shoots); abaxial surface of bracts and bracteoles pubescent; corolla yellow, 12-20 mm long, externally pubescent; seeds ± smooth...................................................................... H. ehrenbergiana

9b. Acaulescent (to subcaulescent) perennial herbs; leaves in a basal cluster; corolla subactinomorphic, pinkish, limb ± rotate; anthers included in corolla tube............................. Stenandrium dulce

10a. Thecae basally awned or mucronate; pollen 3-colporate, mesocolpia multi-striate with pseudoclopi............................................................................. Dyschoriste

a. Glandular trichomes present on some or all of the following: young stems and leaves, bracteoles, calyx, and external surface of corolla.................................... D. hirsutissima

a’. Glandular trichomes absent....................................................... b

b. Plants erect, up to 1 m or more tall; leaves ovate to elliptic, not conduplicate (17–) 25–110 mm long, 8–50 mm wide................................................... D. quadrangularis

b’. Plants mostly prostrate, decumbent, scrambling, or if erect, then up to ca. 3 dm tall; leaves linear to oblanceolate to obovate to obovate-elliptic, often conduplicate, 8–33 mm long, 1–11 (–14) mm wide.......................................................................... c

c. Leaves oblanceolate to obovate to obovate-elliptic, margin crenulate-sinuate (at least distally........................................................................ D. crenulata

c’. Leaves linear to linear-oblanceolate, margin entire.................................... d

d. Internodes glabrous or very sparsely pubescent with retrorse trichomes 0.1– 0.2 mm long.......................................................................... D. greenmanii

d’. Internodes ± conspicuously pubescent with flexuose to retrorse trichomes to 0.3 mm long.......................................................................... D. schiedeana

10b. Thecae lacking basal awns or mucros; pollen otherwise.................................... 11

11a. Plants submersed or emergent aquatics, corolla 8–16. 5 mm long (septa and retinacula remaining attached to inner capsule wall at maturity), limb zygomorphic (conspicuously 2-labiate); pollen 4-colporate, mesocolpia each with 2–3 pseudocolpi...................................... Hygrophila corymbosa

11b. Plants terrestrial; corolla 20–60 mm long (or 10–20 mm long in R. blechum , which has septa and attached retinacula separating from inner capsule wall at maturity), limb subactinomorphic; pollen 3-porate.................................................................................... Ruellia

a. Inflorescences of terminal, 4-sided, densely bracteate spikes; calyx 2.5– 5 mm long; corolla 10–20 mm long, limb 4–11 mm in diameter; capsule 5. 5–7 mm long, septa with attached retinacula separating from inner wall of mature capsule.................................... R. blechum

a’. Inflorescence of 1–many-flowered, sessile to long pedunculate, dichasia in leaf axils; calyx (5.5–) 7–25 mm long; corolla 21–70 mm long, limb 10–49 mm in diameter; capsule 8–29 mm long, septa with attached retinacula remaining attached to inner wall of mature capsule................ b

b. Leaves, bracteoles, calyx, corolla, and capsule (at least near apex) beset with conspicuous punctate glands 0.05– 0.1 mm in diameter; inflorescence of sessile to subsessile (peduncles to 1 mm long) dichasia in leaf axils, dichasia 1 (–2)-flowered; capsule 8–11 mm long; seeds 4 per capsule........................................................................ R. hookeriana

b’. Leaves, bracteoles, calyx, corolla, and capsule without conspicuous punctate glands (sparse and/or inconspicuous punctate glands 0.01- 0.1 mm in diameter sometimes evident on abaxial surface of leaves of R. simplex ); inflorescence of pedunculate (peduncles 3–90 mm long) expanded dichasia in leaf axils, dichasia mostly 3–many-flowered (distal dichasia of R. ciliatiflora subsessile to pedunculate in axils of reduced leaves or bracts, congested or expanded, and often forming a terminal leafy thyrse); capsule 10–29 mm long; seeds 8–22 per capsule........................... c

c. Limb of corolla 10–25 mm in diameter; seeds with trichomes restricted to margin, forming a conspicuous marginal band................................................ R. paniculata

c’. Limb of corolla 18–49 mm in diameter; seeds with trichomes covering entire surface and margin.............................................................................. d

d. Internodes of young stems and peduncles of dichasia pubescent with glandular and eglandular trichomes; capsule 10–22 mm long, pubescent with glandular and eglandular trichomes; seeds 8–12 per capsule.......................................................... R. ciliatiflora

d’. Internodes of young stems and peduncles of dichasia usually glabrous (stems sometimes pubescent with sparse eglandular trichomes and peduncles sometimes with a few scattered eglandular or glandular trichomes); capsule 20–29 mm long, glabrous or with inconspicuous glandular trichomes at apex only; seeds 16–22 per capsule......................................... R. simplex

12a. Androecium of 2 stamens and 2 staminodes.............................................. 13

12b. Androecium of 2 stamens and 0 staminodes............................................. 14

13a. Plants submersed or emergent aquatics; corolla 4.5– 5.5 mm long, ± funnelform, tube short, limb zygomorphic (conspicuously 2-labiate); capsule 5–6 mm long, distally pubescent; pollen 3–4-colporate, mesocolpia each with 3–4 pseudocolpi...................................... Hygrophila polysperma

13b. Plants terrestrial; corollas 20–45 mm long, subsalverform, tube elongate, limb subactinomorphic; capsule 10–16 mm long, glabrous; pollen 3-colporate, mesocolpia each with 2 pseudocolpi................................................................................... Pseuderanthemum

a. Calyx 1.5– 3 mm long; external surface of corolla glabrous; flowers heterostylous; leaves present during anthesis........................................................ P. alatum

a’. Calyx 3. 8–9 mm long; external surface of corolla (at least throat and limb) pubescent; flowers homostylous; leaves mostly or entirely absent during anthesis (of chasmogamous flowers ........................................................................... P. praecox

14a. Young stems mostly hexagonal in cross-section; inflorescence units consisting of cymes bearing 1–5 cymules, cymules consisting of 1 or more flowers subtended by an involucre of 2 or more pairs of bracteoles, the outer cymule bracteoles linear to oblanceolate to obovate to spatulate to hourglass shaped, conspicuous and larger that inner pair(s); capsules with septa and attached retinacula separating from inner capsule wall at maturity and protruding prominently from each capsule valve, mature capsule conspicuously ruptured near base of head................................................. Dicliptera

a. Corolla not resupinate, red, 24–30 mm long.............................. D. sexangularis

a’. Corolla resupinate, pinkish, 15–18 mm long.............................. D. sumichrastii

14b. Young stems mostly terete to quadrate in cross-section; inflorescence various, but not as described above, cymules not present; capsules with septa and retinacula remaining attached to inner capsule wall at maturity or retinacula separating slightly near base of head (i.e., Henrya and Tetramerium ) but not protruding prominently from each capsule valve, mature capsule not or barely ruptured near base of head...... 15

15a. Upper lip of corolla rugulate (i.e., centrally enfolded into a stylar furrow); anther thecae collateral to superposed, parallel to perpendicular, usually one or both with a basal appendage (absent in J. canbyi and J. leonardii .................................................................... Justicia

a. Calyx 4-lobed, or if 5-lobed then lobes conspicuously unequal in length with posterior lobe up to 1/2 as long as other lobes......................................................... b

a’. Calyx 5-lobed, lobes equal or subequal in length...................................... c

b. Corolla pink, tube cylindric nearly throughout; thecae maroon, 0.8– 1.3 mm long, glabrous, lacking basal appendages; pollen apertures flanked on each side by 2 rows of insulae; capsule 9–13. 5 mm long; seeds 2.6– 3 mm long, surfaces and margin gemmate, lacking trichomes or bristles J. canbyi

b’. Corolla greenish or yellowish white tinged with pink or maroon, tube conspicuously and abruptly expanded distally (funnelform); thecae greenish yellow, 1.2– 2.5 mm long, dorsally pubescent with eglandular trichomes, lower theca with basal appendage to 1.5 mm long; pollen apertures flanked on each side by 1 row of insulae; capsule 14–20 mm long; seeds 3–4 mm long, surfaces and margin covered with subconic trichomelike barbed bristles........................ J. salviiflora

c. Leaves mostly crowded at nodes of new growth, sessile, linear to filiform, 0.5– 2 mm wide, margin revolute; (inflorescence of sessile dichasia in leaf axils, corollas externally pubescent with eglandular trichomes only, and margins of calyx lobes neither hyaline nor discolored); Chihuahuan desertscrub............................................................. J. linearis

c’. Leaves not mostly crowded at nodes of new growth, subsessile to petiolate, lance-ovate to ovate to elliptic to broadly elliptic, 2. 6–71 mm wide, margin not revolute (or if, as in J. pacifica , leaves sometimes sessile, linear, and 2.6 mm wide, then margin not revolute, inflorescences mostly in spikes, external pubescence of corollas including glandular trichomes, and margins of calyx lobes hyaline to whitish or much lighter green than remainder of calyx); various biotic communities........ d

d. Corolla orange to reddish orange, lacking colored markings, subfusiform to fusiform in bud, lower lip usually recoiled; inflorescence of spikes or panicles of spikes with bracts and bracteoles triangular to subulate, 0.9– 2.2 mm long, and abaxially pubescent with eglandular trichomes only; capsule 15–21 mm long, appearing glabrous but inconspicuously pubescent with sessile to subsessile glands less than 0.05 mm long............................................ J. leonardii

d’. Corolla color various (if orange, as in J. fulvicoma , then either with additional colored markings present and/or lower lip not recoiled), obovoid to subcylindric to apically curved in bud, lower lip not recoiled; inflorescence not as described above; capsule 5–15 mm long, glabrous or pubescent with eglandular trichomes only..................................................... e

e. Petioles usually inconspicuously glandular on abaxial surface; bracts of axillary spikes (when present) heteromorphic (i.e., sterile bracts smaller than fertile bracts); calyx lobes with margins hyaline to whitish or much lighter green than remainder of calyx; corolla tube ± abruptly expanded several mm from base; staminal filaments pubescent with glandular trichomes; thecae greenish; seeds subglobose, surface smooth, pubescent with deciduous trichomes................. J. pacifica

e’. Petioles lacking glands on abaxial surface; bracts (when present) homomorphic; calyx lobes with margins not differentiated from remainder of calyx; corolla tube cylindric or gradually expanded distally; staminal filaments pubescent with eglandular trichomes; thecae not greenish; seeds discoid, surface appearing smooth (minutely granulate), or rugose with tubercles, lacking trichomes .............................................................................. f

f. Inflorescence of dichasia in leaf axils, leaves bearing dichasia green; corolla pinkish with white markings, externally pubescent with glandular (sometimes sparse and inconspicuous) and eglandular trichomes, tube cylindric (longer than limb); thecae glabrous; capsule glabrous; pollen 2-aperturate................................................................. J. pilosella

f’. Inflorescence of axillary and/or terminal, densely bracteate, 4-ranked spikes, bracts entirely maroon or with some red or maroon discoloration; corolla white with maroon markings or orange sometimes with red spots, externally pubescent with eglandular trichomes only; tube gradually expanded distally (or if not or only slightly expanded distally, then not longer than limb); thecae dorsally pubescent; capsule pubescent with eglandular trichomes; pollen 3-aperturate........ g

g. Calyx 3.5– 3.7 mm long; corolla 11–12 mm long, tube not or only slightly expanded distally; thecae 1.2– 1.5 mm long............................................................. J. sp.

g’. Calyx 4–7 mm long; corolla 25–38 mm long, tube gradually expanded distally; thecae 1.7– 3.2 mm long.......................................................................... h

h. Inflorescence drooping or nodding; corolla white (to yellowish) with maroon markings; bracts broadly ovate to ovate; dichasia alternate; seeds appearing smooth (minutely granulate)........................................................................ J. brandegeeana

h’. Inflorescence erect; corolla orange (sometimes with reddish or yellowish markings); bracts lanceolate to ovate to elliptic; dichasia opposite; seeds rugose with rounded to subconic tubercles......................................................................... J. fulvicoma

15b. Upper lip of corolla not rugulate; anther thecae collateral (or slightly offset), parallel to subsagittate, lacking basal appendages................................................................. 16

16a. Corolla (28–) 35–47 mm long, lemon yellow without colored markings, throat slightly saccate; bracts maroon (at least distally); calyx 11–25 mm long; capsule 15. 5–25 mm long...... Hoverdenia speciosa

16b. Plants not with the above combination of characters....................................... 17

17a. Corolla 22–45 mm long............................................................. 18

17b. Corolla 6. 5–20 mm long............................................................. 19

18a. Inflorescence of mostly loosely and inconspicuously bracteate unilateral spikes or racemes; bracts lanceolate to lance-subulate, 0.5–1.5 (–3.5) mm wide, often caducous; corolla red, tube gradually expanded distally............................................................ Anisacanthus quadrifidus

18b. Inflorescence of densely and conspicuously bracteate 4-sided spikes; bracts lance-ovate to ovate-elliptic to broadly ovate to subdeltate, 5–18 mm wide, persistent; corolla blue, pale purple, or pinkish, tube slender and not (or only very slightly) expanded distally................................... Yeatesia

a. Young stems pubescent with trichomes 0.05– 0.2 mm long; leaf blades linear-elliptic to lanceolate to ovate, 2. 8–17 mm wide; bracteoles 0.05–2 mm long; calyx 1.5– 3.5 mm long; capsule 7–10 mm long, usually 2-seeded...................................................... Y. platystegia

a’. Young stems pubescent with trichomes 0.3– 1 mm long; leaf blades ovate, 19–68 mm wide; bracteoles 9–20 mm long; calyx 5. 5–10 mm long; capsule 11–14 mm long, usually 4-seeded.. Y. mabryi

19a. Capsule 4. 2–7 mm long, retinacula separating slightly from inner wall of mature capsule; seeds 1.2– 2.2 mm long; corollas cream to yellow...................................................... 20

19b. Capsule 7–12 (–16) mm long, retinacula remaining attached to inner wall of mature capsule; seeds 3.5– 5 (–5.8) mm long; corolla white, blue, or purplish.......................................... 21

20a. Bracteoles fused along one side from base to apex forming a conspicuous floral involucre; inflorescence neither densely bracteate nor 4-ranked; bracts shorter than bracteoles; seeds 2, pubescent on one side with stiff interwoven hygroscopic trichomes; pollen with colpi broad, far exceeding width of centrally positioned ora.............................................................. Henrya insularis

20b. Bracteoles fused, if at all, only at base up to 1 mm, not forming a floral involucre; inflorescence densely bracteate and 4-ranked; bracts longer than bracteoles; seeds 4, lacking trichomes; pollen with colpi narrow, not or barely exceeding width of centrally positioned ora................ Tetramerium nervosum

21a. Flowers nototribic (i.e., with stamens closer to upper lip and anthers dehiscing toward lower lip of corolla); corollas blue to purplish, concolorous or with white markings on lower lip, lacking yellow, maroon, or darker purple markings; style curved downward near apex; densely branched, woody shrubs.. Mirandea

a. Bracts linear to oblanceolate, 8–16 (–20) mm long; calyx 5–7 mm long; style glabrous; capsule glabrous; Tamaulipan thornscrub........................................ M. andradenia

a’. Bracts lanceolate to subulate, 3. 5–8 mm long; calyx 3.5– 4 mm long; style pubescent; capsule pubescent; Chihuahuan desertscrub......................................... M. grisea

21b. Flowers stenotribic (i.e., with stamens closer to lower lip and anthers dehiscing toward upper lip of corolla); corolla white (with or without colored markings) or blue to purplish (with yellow + maroon or darker blue/purplish + white markings); style straight near apex; mostly perennial herbs or if shrubby, then ± loosely branched........................................................... Carlowrightia

a. Corolla white, lacking colored marking, subactinomorphic; seeds 2, prominently tuberculate on concave side and papillose on convex side, additional seeds (if present) thinner, partially folded, and with exaggerated marginal teeth........................................ C. albiflora

a’. Corolla blue to purplish, or if white, then with colored markings on upper lip, zygomorphic (or sometimes ± subactinomorphic in C. parviflora ); seeds usually 4 and homomorphic.......... b

b. Young stems bisulcate; corolla blue with white and darker blue/purplish markings on upper lip, lower-central lobe usually not prominently keel-like and enclosing stamens and style; anthers golden yellow...................................................................... c

b’. Young stems terete to quadrate (and sometimes also multi-striate]; corolla white with colored markings, or if blue-purple then with a yellow eye streaked with purple veins on upper lip, lower lip prominently keel-like and usually enclosing stamens and style; anthers maroon.............. d

c. Internodes pubescent with trichomes to 1.5 mm long; leaves cordate, margins not revolute, evenly hirsute-ciliate; capsule 10.5–11. 5 mm long, pubescent, seeds 4– 4.8 mm long.... C. hapalocarpa

c’. Internodes pubescent with retrorse trichomes to 0.2 (–0.4) mm long or glabrous; leaves linear to lanceolate to ovate, margins revolute, hirsute-ciliate only near base, if at all; capsule 8–10. 5 mm long, glabrous; seeds 3–4 mm long....................................... C. parviflora

d. Capsule pubescent................................................... C. trichocarpa

d’. Capsule glabrous............................................................... e

e. Corolla white with yellow and maroon markings on upper lip, 15–20 mm long; capsule 10–16 mm long.................................................................. C. neesiana

e’. Corolla blue-purple with yellow and darker purplish markings on upper lip, 9–12 mm long; capsule 7–9. 5 mm long .................................................. C. henricksonii