Carlowrightia purpurea T.F.Daniel

  • Authority

    Daniel, Thomas F. 1983. Carloivrightia (Acanthaceae). Fl. Neotrop. Monogr. 34: 1-116. (Published by NYBG Press)

  • Family

    Acanthaceae

  • Scientific Name

    Carlowrightia purpurea T.F.Daniel

  • Type

    Type. Mexico. San Luis Potosí: along Hwy. 69, 13.3 mi S jct. Hwy. 69 and Hwy. 70 in Rio Verde, ca. Lat. 21° 50' N, Long. 99° 55' W, elev. 900-1200 m, 26 Jul 1978, Daniel 351 (MICH!, holotype; ENCB!, F!, GH!, MEXU!, MO!, NY!, US!, isotypes).

  • Description

    Latin Diagnosis - Suffrutex usque ad 3(-5) dm altus. Caules juniores quadrati vel teretes, pubescentes. Folia petiolata; Petioli l-10(-20) mm longi; laminae (deltatae) late ovatae vel obovatae, 4-25(-45) mm longae, 2-26(-38) mm latae, 1-2-plo longiorae quam latiorae. Redacta dichasia floribus 1-3, sessilia in axillis foliorum vel axillis bractearum. Calyces 3.1-7.0 mm longi, extus glandulosi. Corollae subbilabiatae, roseolae-purpureae labio superiore in centro luteo excepto, 9-13 mm longae. Capsulae 9-11 mm longae, pubescentes. Semina 3.6-5.2 mm longa, 3.3-4.3 mm lata; testae laeves vel papillosae, mar-ginibus integrae vel crenulatae.

    Species Description - Decumbent to erect suffrutescent perennial to 3(-5) dm high, arising from a woody caudex to 7 mm in diameter or a woody rhizome to 2 mm in diameter. Older stems quadrate to terete or with irregularly fissured bark, 1-2 mm in diameter, pubescent or glabrate. Younger stems gray-green, often tinged with red, quadrate to terete, smooth to multistriate, 0.5-1.5 mm in diameter, pubescent with an understory of eglandular, retrorse (to erect) trichomes 0.2-0.5 mm long (strigose), usually concentrated in 2 vertical, often decussate lines, and an overstory of eglandular, erect to flexuose trichomes 0.5-1.5 mm long (hirsute), more or less evenly disposed, rarely with scattered glandular trichomes 0.2-0.8 mm long as well. Leaves ascendent to horizontal, petiolate; petioles 1-10(-20) mm long, pubescent like younger stems; laminas often tinged with red, especially along the margins, (deltate) broadly ovate to ovate (obovate), 4-25(-45) mm long, 2-26 (-38) mm wide (often reduced in size acropetally into flower-bearing bracts), mostly 1-2 times longer than wide, truncate to acute (or frequently oblique) at base, acute at apex; margins flat, entire to minutely undulate, strigose-hirsute-ciliate; surfaces strigose-hirsute, especially along the veins; several orders of venation evident. Reduced dichasia solitary or opposite at the nodes, sessile in the leaf axils or in axils of bracts in a terminal, leafy spicate axis to 15 cm long. Inflorescence axis (when present) pubescent with a mixture of eglandular and glandular trichomes, the eglandular trichomes erect, 0.3-1.0(-1.5) mm long, the glandular trichomes 0.2-0.8 mm long; flowers 1-3 (or more) per dichasium, each sessile or short (to 0.5 mm long) pedicellate, subtended by 2 bractlets. Bracts petiolate, deltate to ovate to elliptic, 3.5-11.0 mm long, 1.8-10.0 mm wide, pubescent like leaves although more glandular. Bractlets and secondary bractlets (if present) sessile or short (to 0.5 mm long) petiolate, subulate to narrowly lanceolate to narrowly elliptic, 2.5-4.0 mm long, 0.4-0.9 mm wide, pubescent like leaves if in lower leaf axils, pubescent like inflorescence axis if in axil of bracts. Calyx 3.1-7.5 mm long, the outer surface pubescent like bractlets, the inner surface sericeous with appressed trichomes to 0.4 mm long; tube 0.5-1.5 mm long; lobes subulate, 2.5-6.0 mm long, 0.4-0.5 mm wide at base. Corolla subbilabiate, light or dark rose-purple with a faint to prominent, papillate yellow eye outlined and streaked with purple veins on the upper lip, 9-13 mm long, pubescent on the outer surface with trichomes 0.05-0.20 mm long; tube 2-3 mm long, 1.0-1.5 mm in diameter; upper lip spatulate, 6-10 mm long, 2.8-3.0 mm wide, entire or emarginate at apex; lower lip 7-10 mm long, the lateral lobes spreading to reflexed, obovate-elliptic, 5.5-7.5 mm long, 2.0-3.3 mm wide, the lower lobe spreading to reflexed, not strongly conduplicate-keeled, elliptic, 4.3-6.5 mm long, 2.0-3.5 mm wide. Stamens 4.0-4.5 mm long, filaments purplish, 3.1-3.5 mm long, 0.3 mm wide at base, pubescent, especially near the base with trichomes 0.05-0.10 mm long; anthers maroon, 0.9-1.2 mm long. Disc 0.2 mm high. Style 5-7 mm long, pubescent at base. Stigma lobes 0.2 mm long. Capsules 9-11 mm long, pubescent with eglandular trichomes 0.2-0.3 mm long; stipe 3-4 mm long; head flattened, 6-7 mm long (including a terminal beak 0.5-1.0 mm long), 4.0-4.5 mm wide; retinacula 1.5-2.0 mm long. Seeds usually 4 per capsule, flat, obliquely cordate in outline, 3.6-5.3 mm long, 3.3-4.3 mm wide, rounded to acute at apex; testa smooth to papillose; margins entire to crenulate. Flowering. This species has been collected in flower in July and September. The plants were flowering in abundance in July and only sporadically in September.

  • Discussion

    Discussion. Carlowrightia purpurea is a relatively common, although local species which had apparently not been collected prior to this study. The local frequency (to even dominance) of Mirandea grisea Rzedowski, a desert shrub in the same general region which was not described until 1959 (Rzedowski, 1959) indicates the lack of botanical exploration in central San Luis Potosí.

    Despite its ability to hybridize with numerous species, the species is most similar to C. trichocarpa which occurs to the northeast, across the Sierra Madre Oriental in Tamaulipas. It differs from C. trichocarpa by its longer, rose-purple corolla, leafy, glandular spike (when present), and entire to crenulate seed margins. In addition, the corolla of C. purpurea exhibits a floral morph intermediate between Types I and II. The lower-central petal lobe of this species is usually reflexed and not strongly conduplicate. In C. trichocarpa, the lower-central lobe forms a distinct keel in which the stamens and style sit.

    The variation encountered in populations of C. purpurea appears to be attributable to the degree of exposure (sun and shade forms are common) as well as grazing. Exposed plants not only have smaller leaves but tend to be prostrate whereas plants growing up through thorn shrubs are spindly and have large leaves. Occasional albinic forms with white corollas with a faint yellow eye (e.g. Daniel 327) coexist with the normally rose-purple flowered individuals.

    Distribution and Ecology: Carlowrightia purpurea is known only from arid and semi-arid regions of San Luis Potosí where it ranges from the thorn scrub of the east-central part of the state northwestward into the Chihuahuan Desert Region. It is especially frequent in exposed areas on rocky or gravelly hills and along roads at elevations of 1000 to 1900 meters.

  • Distribution

    Mexico North America| San Luis Potosí Mexico North America|