Carlowrightia linearifolia (Torr.) A.Gray

  • Authority

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

  • Family

    Acanthaceae

  • Scientific Name

    Carlowrightia linearifolia (Torr.) A.Gray

  • Type

    Type. United States. Texas: Culberson-Jeff Davis County border, between the Chispa Mountains and Lobo Siding, 28 Aug 1849, Wright 436 (US!, lectotype; GH!, PH!, TEX!, isolectotypes).

  • Synonyms

    Schaueria linearifolia Torr., Dianthera linearifolia (Torr.) Benth. & Hook.f. ex B.D.Jacks.

  • Description

    Species Description - Erect, openly branched shrub (l-)5-10(-20) dm high, arising from a woody caudex to 25 mm in diameter. Older stems terete, 2-8 mm in diameter, glabrate. Younger stems green, terete, multistriate with numerous inconspicuous ridges and grooves, 1-2 mm in diameter, evenly pubescent, the trichomes eglandular, erect, 0.02-0.10 mm long (puberulent). Leaves often subopposite, ascendent, sessile (rarely subsessile with petioles 0.5 mm long); laminas linear, 10-55 mm long, 0.5-2.0(-3.0) mm wide (reduced in size acropetally to flower-bearing bracts), mostly (5-)10-25(-35) times longer than wide, attenuate to acute at base, rounded to acute at apex; margins flat, puberulent-ciliate; surfaces puberulent; midvein only evident on both surfaces. Inflorescence typically consisting of 1 or more racemose or thyrsoid axes to 25 cm long, collectively forming a terminal, leafy panicle or thyrse. Inflorescence axes puberulent. Reduced dichasia solitary or usually opposite at the nodes along the inflorescence axes, each sessile or pedunculate in the axil of a leaf or bract, the peduncles 1.5-20.0 mm long; flowers 13 per dichasium, each sessile or pedicellate subtended by 2 bractlets, the pedicels 0.5-1.5 mm long, the lateral flowers borne on secondary peduncles. Bracts linear, (1.5-)3-20(-35) mm long, 0.4-1.0 mm wide, puberulent. Bractlets linear, 1-10 mm long, 0.3-0.6 mm wide, puberulent. Secondary bractlets linear, 0.5-3.0 mm long, 0.2-0.4 mm wide. Calyx 1.5-5.2 mm long, the outer surface sparsely to densely puberulent, the inner surface glabrous to puberulent; tube 0.5-1.5 mm long; lobes linear to triangular, 1.0-4.8 mm long, 0.5-0.8 mm wide at base. Corolla subactinomorphic, lavender blue with faint yellow to white papillate eye outlined and streaked with purple veins on the upper lip, (7.5-)9-12 mm long, glabrous (rarely very sparsely puberulent) on outer surface; tube 3.0-5.0 mm long, 1.3-2.0 mm in diameter; upper lip obovate to spatulate, 4.5-8.0 mm long, 1.5-3.0 mm wide, entire or emarginate at apex; lower lip 5.0-8.0 mm long, the lobes identical in form, reflexed, oblanceolate to elliptic, 4.5-7.5 mm long, 1.5-3.0 mm wide. Stamens 5.5-6.0 mm long; filaments purple, 4.3-5.5 mm long, 0.3-0.4 mm wide at base, pubescent with trichomes 0.1-0.2 mm long; anthers golden yellow, thecae 1.1-1.9 mm long. Disc 0.4-0.5 mm high. Style 7.5-8.0 mm long, glabrous. Stigma lobes 0.2-0.3 mm long. Capsules 10.5-12.2 mm long, glabrous; stipe 4.5-6.0 mm long; head spherical to partially flattened, 6.0-7.0 mm long (including a terminal beak 0.8-1.2 mm long), 4.0-5.0 mm wide; retinacula 2.5-3.8 mm long. Seeds usually 4 per capsule, flat, obliquely circular to cordate in outline, 3.8-4.5 mm long, 3.5-4.5 mm wide, rounded at apex; testa papillose; margins entire. Flowering. This species usually begins to flower in late July, reaches a peak in August and September and continues to flower sporadically into early December.

  • Discussion

    Discussion. This species was lectotypified by Daniel (1981) from among the specimens of C. linearifolia and Justicia warnockii Turner cited in Torrey’s protologue of Schaueria linearifolia. Examination of Wright’s field notes by Dr. Elizabeth Shaw of the Gray Herbarium revealed the date and location of the collection.

    Carlowrightia linearifolia differs from other species in section Carlowrightia by its terete, multistriate (rather than bisulcate) stems, short trichomes, flat and linear laminas, relatively long retinacula, and entire seed margins. In addition, the eye on the upper lip of the corolla is often yellowish and apparently always papillate whereas in the other species in this section the eye is white and lacks papillae. Its closest relative may be C. parviflora which frequently has linear leaves (but with revolute margins). Although primarily a Chihuahuan Desert species, C. linearifolia occurs in the Cochise filter barrier (Morafka, 1977) of southeastern Arizona and southwestern New Mexico. The species does not appear to occur in the Sonoran Desert, however.

    The only population of C. linearifolia observed in the field contained approximately 25 plants, four of which had albinic corollas. The corollas on these otherwise normal plants were white with a faint yellowish eye on the upper lip.

    The most variable features of C. linearifolia are the development of the dichasia, the length of bracts, bractlets, and secondary bractlets, and the form and pubescence of the calyx. The dichasia on one individual may vary from being pedunculate and having a pedicellate central flower with two lateral flowers on secondary peduncles to being sessile and consisting of a single, sessile flower. The bracts, bractlets, and secondary bractlets are extremely variable in length, but the bracts are usually longer than the bractlets and the bractlets are usually longer than the secondary bractlets. The leaves, bracts, bractlets, and secondary bractlets form a heteroblastic series in which there has been little alteration of shape or pubescence, the only difference among them being size.

    The calyx of C. linearifolia is usually about 2.5 to 5.0 mm long, with linear, rather densely puberulent lobes. In contrast, specimens from the southeastern portion of the range (Brewster County, Texas, and Coahuila) usually have calyces about 1.5 to 3.0 mm long, with triangular to linear, sparsely puberulent lobes. There is, however, some overlap in form and pubescence of the calyx throughout the range of the species, and the calyx size may vary rather greatly on an individual. Rarely, one of the calyx lobes will be only one-half to two-thirds as long as the others.

  • Distribution

    Distribution and Ecology: Carlowrightia linearifolia ranges from the Trans-Pecos region of western Texas, westward through southern New Mexico into southeastern Arizona, and southward into adjacent regions of Chihuahua and Coahuila (Fig. 17). It is found in rocky washes and in the gravelly or sandy alluvium of arroyos in desert associations with species of Fouquieria, Agave, Ephedra, Prosopis, Acacia, Mimosa, Dasylirion, and Larrea at elevations of 900 to 1750 meters.

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