Carlowrightia pringlei B.L.Rob. & Greenm.

  • Authority

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

  • Family

    Acanthaceae

  • Scientific Name

    Carlowrightia pringlei B.L.Rob. & Greenm.

  • Type

    Type. Mexico. Oaxaca: Tomellin Canyon, 3500 ft, 30 Nov 1895, Pringle 6261 (GH!, holotype; ENCB!, F!, MO!, MSC!, NY!, UC!, US!, isotypes).

  • Synonyms

    Siphonoglossa pringlei (B.L.Rob. & Greenm.) Lindau

  • Description

    Species Description - Erect to spreading shrub to 1.5 m high. Older stems terete or with irregularly fissured bark, 1-6 mm in diameter, glabrate. Younger stems green, quadrate to terete, smooth to multistriate, 0.5-1.0 mm in diameter, glabrous or more commonly pubescent with eglandular, retrorse trichomes 0.1-0.3 mm long (strigillose), concentrated in 2 vertical, decussate lines, the nodes pubescent with eglandular, erect trichomes 0.2-1.0 mm long (floccose). Leaves horizontal to ascendent, petiolate; petioles 0.8-10.0(-20.0) mm long, pubescent like the younger stems, occasionally with trichomes to 1 mm long as well; laminas lanceolate to narrowly ovate (ovate), 5-40 mm long, 2-20 mm wide (reduced in size acropetally into flower-bearing bracts), mostly 2.0-4.5 times longer than wide, acute to rounded to truncate to subcordate (often oblique) at base, acuminate at apex; margins flat, ciliate with trichomes 0.1-1.0 mm long; surfaces glabrous or pubescent with eglandular trichomes 0.05-1.00 mm long, especially along the veins; several orders of venation evident. Inflorescence typically consisting of 1 or several spicate axes to 16 cm long, collectively forming a terminal, somewhat leafy panicle. Inflorescence axes pubescent like the younger stems or pubescent with a mixture of eglandular and glandular trichomes, the eglandular trichomes erect, 0.1-0.4 mm long, the glandular trichomes 0.1-0.3 mm long. Reduced dichasia solitary at the nodes, sessile or short (to 1 mm long) pedunculate in the axil of a reduced upper leaf or bract; flowers 1 (-3) per dichasium, each sessile or short (to 1 mm long) pedicellate, subtended by 2 bractlets. Bracts sessile or usually petiolate, narrowly lanceolate to narrowly elliptic to ovate, 1-5(-12) mm long, 0.5-2.0 mm wide, pubescent like leaves. Bractlets and secondary bractlets sessile, subulate, 1.5-3.0 mm long, 0.3-0.5 mm wide, pubescent like leaves. Calyx accrescent, (2.5-)4.0-5.0(-6.0) mm long, the outer surface pubescent with a mixture of eglandular and glandular trichomes 0.05-0.80 mm long, the inner surface glabrous, or glandular pubescent with trichomes 0.05 mm long, or sericeous with appressed, eglandular trichomes to 0.3 mm long; tube 0.5-2.0 mm long; lobes subulate, (1.5-)3.0-5.0 mm long, 0.7-0.9 mm wide at base. Corolla pseudopapilionaceous, very light to bright blue, the upper lip with a white to yellow, papillate eye fringed with radiating purple veins (often restricted to the base of the eye), (18-)23-27 mm long, pubescent on the outer surface of the lower central lobe with trichomes 0.1-0.4 mm long; tube 9-13 mm long, 2.0-2.2 mm in diameter; upper lip spatulate, 11-14 mm long, 5.0-6.5 mm wide, emarginate at apex; lower lip 11-15 mm long, the lateral lobes obovate-elliptic, 10-14 mm long, 7-9 mm wide, the lower lobe conduplicate-keeled, 10-13 mm long, 5.0-6.5 mm wide. Stamens 8-10 mm long; filaments bluish, 7.0-8.5 mm long, 0.3-0.5 mm wide at base, strigillose, especially near the base; thecae maroon turning black, 1.5-1.7 mm long. Disc 0.4-0.5 mm high. Style 20-26 mm long, glabrous or strigillose along the lower half. Stigma lobes 0.2-0.3 mm long. Capsules 11-15 mm long, glabrous; stipe 5-8 mm long; head flattened, 6-8 mm long (including a terminal beak to 1.5 mm long), 4.2-5.8 mm wide; retinacula 2-3 mm long. Seeds usually 4 per capsule, flat, obliquely cordate in outline, 4-5 mm long, 3.5-4.5 mm wide, rounded at apex; testa smooth; margins entire. Flowering. Carlowrightia pringlei flowers from late October through January.

  • Discussion

    Discussion. In their description of C. pringlei, Robinson and Greenman questioned the placement of the species in Carlowrightia. Lindau (1897) claimed the species was a typical Siphonoglossa based on the form of the corolla and the pollen. Although the corolla tube of C pringlei is longer than in most other species of Carlowrightia, it is neither erect nor ampliate near the apex as are the corolla tubes in Siphonoglossa. The pollen of C. pringlei is tricolporate with six pseudocolpi rather than being biporate to triporate with rows of insulae flanking the pores as in species of Siphonoglossa (Henrickson & Hilsenbeck, 1979).

    Morphologically, C. pringlei appears to be most closely related to C. glandulosa, within whose range it occurs. It differs from this species by its corolla which is bluish within (vs. white within) and which has a long (9-13 mm) tube (vs. 3.5-9.0 mm), and by the absence of glandular trichomes on the vegetative shoots. Carlowrightia pringlei differs from all the species of section Pseudopapilionacea by the length of its style (20-26 mm long) which is exserted from the fully opened corolla. Herbarium specimens and field observations reveal that in almost all instances, the style extends beyond the lower-central petal lobe, well out of contact with the anthers. This separation of the stigma from the anthers is suggestive of a mechanism to encourage outcrossing in C. pringlei. It is not known if this species is self-compatible, but as all other species in the genus examined so far are, it is likely that C. pringlei will be found to be so. The well-developed keel probably functions in effecting self-pollination (by the method described under Reproductive Biology) if visitors fail to pollinate the stigmas.

    The specimens of C. pringlei from the northern part of the range in Puebla differ from most of the Oaxacan material in pubescence and bract size. In the former specimens, the inflorescence axes are pubescent with a mixture of evenly disposed, eglandular and glandular trichomes 0.2 to 0.4 mm long; the inner surface of the calyx is sericeous; and the style is sparsely pubescent. In most of the specimens from Oaxaca, the inflorescence axes are pubescent with retrorse, eglandular trichomes 0.05 to 0.10 mm long, disposed in two vertical lines; the inner surface of the calyx is glabrous or minutely glandular; and the style is glabrous. In two collections from Oaxaca (Seler & Seler 1756, 4873), however, the inflorescence axes are pubescent like the Pueblan material and the inner surface of the calyx is often sericeous in Seler & Seler 1756 and 4843. The bracts of the Pueblan specimens tend to be smaller (1-3 mm long) and ovate to elliptic whereas the bracts of the Oaxacan specimens are usually larger (1.5-12.0 mm long) and more narrowly lanceolate to narrowly elliptic. There is considerable overlap in the size and form of the bract, however.

    The specimens from Puebla appear to come from two regions approximately 50 kilometers apart. They show little, if any, divergence in the above characters. The absence of collections between these populations may reflect the lack of a highway in this region along which specimens can be easily taken, rather than the absence of the species there. With one exception, the specimens from Oaxaca all appear to have been collected between Etla and Teotitlan del Camino, in a region contiguous with the Pueblan populations. Pringle’s collection (565J) from this region differs from the other Oaxacan material in that the leaf laminas are very reduced (to 10 mm long and 4 mm wide) and the calyx ranges in length from 2.5 to 3.5 mm. His specimens may represent sun or drought forms of the species. Seler and Seler collected a specimen (1756) near Tehuantepec, approximately 200 kilometers southeast of the other Oaxacan populations. This specimen more closely resembles the Pueblan material than most of the other specimens from Oaxaca.

  • Distribution

    The range of C. pringlei extends for approximately 150 kilometers in the mountainous area of northwestern Oaxaca and southeastern Puebla (Fig. 19) where it occurs on rocky slopes in arid and semi-arid associations with species of Acacia and columnar cacti at elevations of 970 to 1600 meters.

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