Carlowrightia torreyana Wassh.

  • Authority

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

  • Family

    Acanthaceae

  • Scientific Name

    Carlowrightia torreyana Wassh.

  • Type

    Type. United States. Texas. Between the Pecos River and San Antonio, summer 1852, Wright 1460 (NY!, lectotype; GH!, MO!, NY!, isolectotypes).

  • Synonyms

    Schaueria parvifolia Torr., Dianthera parvifolia (Torr.) A.Gray, Carlowrightia pubens A.Gray, Ecbolium parvifolium (Torr.) Kuntze, Croftia parvifolia (Torr.) Small

  • Description

    Species Description - Decumbent to erect, suffrutescent perennial to 5 dm high, arising from a woody caudex to 13 mm in diameter or a woody rhizome to 3 mm in diameter. Older stems quadrate to terete or with irregularly fissured bark, 1.0-2.5 mm in diameter, pubescent or glabrate. Younger stems green to gray-canescent, quadrate to terete, smooth to multistriate, 0.5-1.0 mm in diameter, evenly and densely pubescent, the trichomes eglandular, erect to flexuose, (0.2-) 1.0- 1.5(-1.9) mm long (hirsute-villous), often with an understory of erect to retrorse trichomes, 0.2-0.3 mm long (strigose). Leaves horizontal to ascendent, petiolate; petioles 2-7(-15) mm long, pubescent like younger stems; laminas broadly ovate to orbicular when larger, ovate-elliptic when smaller, (5-)10-20(-40) mm long, (3-)7-13(-27) mm wide (often reduced in size acropetally into flower-bearing bracts), mostly 1-3 times longer than wide, truncate to rounded to acute (or frequently oblique) at base, rounded to acute at apex; margins flat, entire or undulate, hirsute-ciliate; surfaces hirsute-villous; several orders of venation prominent. Reduced dichasia solitary or opposite at the nodes, sessile in leaf axils, or more commonly sessile in axils of bracts in an inflorescence consisting of 1 or more slender, spicate axes, (3-)5-8(-13) cm long, from the upper nodes. Inflorescence axes pubescent usually with a mixture of eglandular and glandular trichomes, the eglandular trichomes like those of the younger stems or sometimes absent, the glandular trichomes (0.1-) 0.2-0.5 mm long, rarely inconspicuous or few in number; flowers 1-3 per dichasium, each sessile to short (to 1 mm long) pedicellate, subtended by 2 bractlets. Bracts sessile, subulate to narrowly ovate, 1.5-4.9 mm long, 0.5-1.6 mm wide, pubescent like leaves or occasionally with glandular trichomes as well. Bractlets subulate, 1.2-3.0 mm long, 0.3-0.7 mm wide (the bractlets subtending flowers in the leaf axils sometimes elliptic, up to 9.5 mm long and 2.0 mm wide), pubescent like bracts. Calyx 2.5-4.0(-5.8) mm long, the outer surface pubescent like bracts, the inner surface sparsely sericeous with appressed trichomes to 0.5 mm long; tube 0.5-1.8 mm long; lobes subulate 2-3(-4) mm long, 0.3-0.5 mm wide at base. Corolla bilabiate, white with a papillate yellow eye bordered by a maroon ring with radiating maroon veins on the upper lip, 7-9 mm long, pubescent on outer surface with trichomes 0.1-0.2 mm long; tube 1.5-2.5 mm long, 1.0-1.2 mm in diameter; upper lip obovate-spatulate 4.0-5.5 mm long, 2.5-3.0 wide, emarginate at apex; lower lip 4.5-6.0 mm long, the lateral lobes spreading or horizontally situated, obovate-elliptic, 4.0-5.5 mm long, 2.5-3.0 mm wide, the lower lobe oblanceolate, conduplicate-keeled, 4.0-5.0 mm long, 2.5-3.0 mm wide. Stamens 4.0-5.5 mm long, filaments white, 3.5-4.7 mm long, 0.1-0.2 mm wide at base, pubescent, especially near the base with trichomes 0.1-0.2 mm long; anthers maroon turning black, thecae 0.6-0.8 mm long. Disc 0.2-0.3 mm high. Style 3.5-5.5 mm long, glabrous. Stigma lobes 0.1 mm long. Capsules 8-12 mm long, glabrous; stipe 3.5-5.0 mm long; head flattened, 4.5-7.0 mm long (including a terminal beak 0.5-1.0 mm long), 3.8-5.0 mm wide; retinacula 2.0-2.5 mm long. Seeds usually 4 per capsule, flat, obliquely cordate in outline, 4.0-4.8 mm long, 3.5-4.5 mm wide, rounded to acute at apex; testa papillose (often only minutely so); margins crenulate to dentate, the teeth often with retrorse barbs. Flowering. Carlowrightia torreyana usually begins to flower in the early spring of (February) March or April, reaches a peak in the late spring, summer, and fall, and tapers off into the winter during which time there may be sporadic flowering.

  • Discussion

    Discussion. Carlowrightia torreyana was lectotypified by Daniel (1981) from among specimens of C. torreyana, C. texana and C. serpyllifolia. Although the precise date and location of Wright’s type collection is not known, considering the range of the species and Wright’s itinerary, it must have been collected during the summer of 1852 between the Pecos River and San Antonio, Texas (Daniel, 1981).

    The species can be distinguished from other species of section Mexicana by its white corolla with a papillate, yellow eye on the upper lip and glabrous capsules. It appears to be most closely related to C. texana, with which it hybridizes in nature, and C. trichocarpa, with which it shares many morphological similarities. Carlowrightia torreyana differs from C. texana by the characters described in the key. In addition, there is a tendency for the development of glandular inflorescence axes in specimens of C. torreyana but not in those of C. texana. The differences between C. torreyana and C. trichocarpa are discussed under the latter species.

    Carlowrightia torreyana is the most crossable of the 10 species grown in the greenhouse. A relatively high degree of fertility results from crosses of C. torreyana with C. texana, C. mexicana, C. trichocarpa, and C. purpurea. It is less fertile with C. serpyllifolia, C. haplocarpa, C. glandulosa, and C. parvifolia. It has been found growing with these latter two species but natural hybrids between them are unknown.

    Although variation in C. torreyana is largely restricted to sun and shade forms similar to those encountered in specimens of C. texana, two collections are worthy of note. In both Correll et al. 28210 from Medina County, Texas, and Daniel 786 from east-central Nuevo Leon, the cauline pubescence is mostly retrorse and varies from 0.2-0.8 mm in length. In both respects, the pubescence resembles that of C. texana. Daniel’s specimen was collected somewhat out of the range of C. torreyana, in the eastern foothills of the Sierra Madre Oriental. It has a uniform pubescence of highly recurved trichomes 0.2 to 0.3 mm long and the leaves vary from lanceolate to ovate. Unfortunately the specimen had no flowers at the time it was collected. It is considered conspecific with C. torreyana based on its glandular spicate axes, glabrous capsules, and denticulate seed margins. The Texas specimen more closely resembles other specimens of C. torreyana with its slightly longer (to 0.8 mm long), although retrorse, trichomes, but the inflorescence axes are not glandular. This specimen is referred to C. torreyana based on the ovate to orbicular leaves, white corollas with papillate, yellow eyes on their upper lips, glabrous capsules, and denticulate seed margins. In addition, it exhibited a high level of pollen stainability (97%).

    Specimens collected by the Mexican Boundary Survey expeditions often lack collector and/or locality information. In addition, numerous specimens (often representing several species) were sometimes mounted on the same sheet without clear correlation of label and specimen, and different species were often placed under the same number. Therefore, in the specimen citations the same collector and number may be listed under more than one species. In cases where there is no clear correlation between label and specimen, the information is omitted from the specimen citations.

    Distribution and Ecology: The range of C. torreyana extends from the south Texas plains, westward across the Edwards Plateau into the Trans-Pecos region of western Texas, southward into the Chihuahuan Desert to central and eastern Coahuila, and eastward to the dry regions around Monterrey (Fig. 26). In the desert, C. torreyana may be found on limestone slopes or along arroyos in associations with species of Agave, Larrea, Dasylirion, Prosopis, Yucca, and Cerco-carpus. Outside of the desert, it commonly occurs in oak woodlands or on gravelly, limestone plains and ledges, especially along streams, in thorn-scrub or bald cypress associations. The species may also become a weed of disturbed habitats such as roadsides and fencerows. It grows at elevations of 250 to 1600 meters.

  • Distribution

    United States of America North America| Texas United States of America North America| Coahuila Mexico North America| Nuevo León Mexico North America|