Carlowrightia albiflora 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 albiflora T.F.Daniel

  • Type

    Type. Mexico. Tamaulipas: thorn scrub along paved Hwy. between Gonzáles and Est. Zaragoza, 1.4 mi SE of turnoff to Est. Zaragoza, ca. Lat. 23° 10' N, Long. 98° 45' W, elev. 290 m, 18 Jul 1978, Daniel 276 (MICH!, holotype; CAS!, ENCB!, F!, GH!, MEXU!, MO!, NY!, TEX!, UC!, US!, isotypes).

  • Description

    Latin Diagnosis - Suffrutex usque ad 3.5 dm altus. Caules juniores striati, pubescentes vel subglabri. Folia petiolata; Petioli 0.5-4 mm longi; laminae lanceolatae (vel ovatae), 8-25 mm longae, 2-15 mm latae, (1.5-)2-4-plo longiores quam latiores. Dichasia redacta 1(-3) floribus, pedunculata in axillis foliorum. Pedunculi 3-13 mm longi. Calyces 2.5-4.0 mm longi, intus subglandulosi. Corollae subactinomorphae, omnino albae, 8-10 mm longae. Capsulae 8-10 mm longae, glabrae. Semina 3.5-3.8 mm longa, 2.62.8 mm lata, testae papillosae vel tubercuiatae ad margines dentatae.

    Species Description - Erect to spreading, spindly subshrub to 3.5 dm high, arising from a woody caudex to 6 mm in diameter. Older stems shallowly striate or with irregularly fissured, corky bark, 1-2 mm in diameter, glabrate. Younger stems green, terete, shallowly multistriate with numerous inconspicuous ridges and grooves, 1.0-1.5 mm in diameter, more or less evenly pubescent (or the pubescence concentrated in 2 vertical lines on opposite sides of the stem) to almost glabrous, the trichomes eglandular, recurved-appressed, 0.1-0.4 mm long (strigose). Leaves ascendent, short petiolate; petioles 0.5-4.0 mm long; laminas lanceolate to ovate, 8-25 mm long, 2-17 mm wide, mostly (1.5-)2.0-4.0 times longer than wide, rounded to cordate at base, acuminate to acute (rarely rounded) at apex; margins flat, ciliate at base, the trichomes flexuose, 0.3-1.0 mm long; surfaces glabrous or scattered strigose along the veins; several orders of venation evident. Reduced dichasia solitary or opposite at the nodes, pedunculate from leaf axils, the peduncles 3-13 mm long; flowers l(-3) per dichasium, each sessile or pedicellate, subtended by 2 bractlets, the pedicels 0.5-1.0 mm long, the lateral flowers (if present) often borne on secondary peduncles to 1 mm long. Bractlets and secondary bractlets (if present) subulate, 1.0-2.0 mm long, 0.4-1.0 mm wide, pubescent like leaves. Calyx 2.5-4.0 mm long, the outer surface glabrous to sparsely strigose, the inner surface more densely pubescent and inconspicuously glandular, the glands 0.050.10 mm long; tube 0.7-1.1 mm long; lobes subulate, 1.8-3.0 mm long, 0.5-0.7 mm wide at base. Corolla subactinomorphic, entirely white, 8-10 mm long, strigose on outer surface; tube 2.5-3.0 mm long, 1.0-1.2 mm in diameter; upper lip elliptic 6.0-7.1 mm long, 1.7-3.0 mm wide, slightly emarginate at apex; lower lip 6.5-7.1 mm long, the lobes identical in form, reflexed, oblanceolate to elliptic, 5.0-6.5 mm long, 1.5-2.5 mm wide. Stamens 4.0-5.0 mm long; filaments white, 3.5-4.3 mm long, 0.2 mm wide at base, pubescent, the trichomes 0.1-0.2 mm long; anthers yellowish, thecae 0.9-1.0 mm long. Disc 0.2-0.3 mm high. Style 4.5-6.0 mm long, glabrous. Stigma lobes 0.2 mm long. Capsules 8-10 mm long, glabrous; stipe 3.5-4.5 mm long; head spherical to partially flattened, 4.5-5.5 mm long (including a terminal beak 0.3 mm long), 4.0 mm wide; retinacula 1.8-2.0 mm long. Seeds usually 2 (rarely 3 or 4) per capsule, concavoconvex, obliquely cordate in outline, 3.5-3.8 mm long, 2.6-2.8 mm wide, acute to rounded at apex; testa tuberculate on concave side, papillose on convex side (third or fourth seeds, if present, often with poorly developed ornamentation on the testa); margins dentate, the teeth often widely scattered, with retrorse barbs. Flowering. This species has been collected in flower in July and September. During a rather severe drought in 1978, C. albiflora was collected during both months and at neither time was there any extensive fruit production, which may have been caused by the apparent lack of pollinators or the severe conditions. Flowering probably continues well into the fall.

  • Discussion

    Discussion. Carlowrightia albiflora is a rare, local species which was known from a single collection prior to this study. It is the only species of Carlowrightia known to have a concolorous corolla. The corolla is entirely white, lacking any markings on the upper lip. The presence of three white-flowered populations in different regions indicates that this type of corolla is the usual situation for C. albiflora, rather than being an albinic form. Even rare, albinic (white-flowered) forms of normally blue-flowered species of Carlowrightia exhibit a faint development of the markings on the upper lip.

    Carlowrightia albiflora is most similar morphologically to C. parvifolia of the Chihuahuan Desert from which it differs most noticeably by its white corolla, petiolate leaves with wide laminas, and glandular calyx (inner surface only).

    In two of the three localities discovered for C. albiflora during this study, the species occurred sympatrically with C. trichocarpa. In neither instance was there any evidence of hybridization.

  • Distribution

    Carlowrightia albiflora is known only from central and southern Tamaulipas, east of the escarpment of the Sierra Madre Oriental (Fig. 14). It grows up through low shrubs in legume and Yucca-dominated thorn-scrub plains and along rocky arroyos at elevations of 300 to 700 meters.

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