Justicia secunda Vahl

Daniel, Thomas F., 2020, Notes on the Vascular Flora of the Island of Príncipe (São Tomé and Príncipe) in the Gulf of Guinea, Proceedings of the California Academy of Sciences 66 (15), pp. 341-352 : 345-346

Justicia secunda Vahl

Príncipe: 0.8 km N of airport terminal along road to Bom Bom Island , 01°40.302ʹN, 007°24.739ʹE, 180 m, disturbed roadside near houses, 1 V 2013 (flr), T . Daniel & A . Stanbridge 12115 ( CAS); along Água Grande, ca. 0.3 km S of entrance to Bom Bom Resort , 01°41.340ʹN, 007°24.126ʹE, ca. 5 m, disturbed moist evergreen forest, 24 IV 2013 (flr), T . Daniel & J . Shevock 12034 ( CAS) . São Tomé: trail from Jardim Botânico de Bom Sucesso (00°16.866ʹN, 006°38.868ʹE; 1115 m) to Lagoa Amélia (00°15.972ʹN, 006°35.589ʹE; 1480 m), moist to wet montane forest and cultivated fields, 14 IV 2008 (flr), T . Daniel 11142 ( CAS) .

This species ( Fig. 3 ), a native of tropical America, was noted by Daniel and Figueiredo (2009) to be cultivated in São Tomé and Príncipe based on plants seen on both islands in 2008. Indeed, the specimen from São Tomé cited above was cultivated as a hedge near the botanical garden, and Daniel & Stanbridge 12115 from Príncipe was both cultivated in a hedge (seen in 2008), but also appeared to be naturalizing nearby (collected in 2013). Daniel & Shevock 12034 from another site on Príncipe (2.2 km distant from Daniel & Stanbridge 12115) consisted of a stand of ca. 100 naturalized and locally frequent plants that confirmed the species escape from cultivation, at least on that island. Infusions and decoctions (including an herbal tea) made from leaves or entire plants of J. secunda have putative medicinal attributes, and are used in both Africa and South America (e.g., Kitadi et al. 2019). Because this species was not treated by Daniel and Figueiredo (2009), a brief description of it (based on the collections cited above) and a revised key to the native and naturalized species of Justicia in the country are provided below.

Perennial herb to shrub to 3.5 m tall; leaves petiolate, blades ovate, 75–140 mm long, 22–53 mm wide, 2.6–3.6 × longer than wide, rounded to acute at base, acuminate at apex, surfaces pubescent with eglandular trichomes restricted to major veins. Inflorescence of axillary and/or terminal panicles of subracemose branches bearing alternate and unilateral (axillary branches) or opposite (terminal portion of main axis) 1-flowered and sessile dichasia. Bracts subtending dichasia subulate to lanceolate, 1–5 mm long (fertile bract usually longer than sterile bract when dichasia unilateral). Paired bracteoles subtending flowers subulate to lanceolate, 1.5-3 mm long. Flowers shortpedicellate, pedicels 0.8–1.5 mm long. Calyx 5-lobed, 6–10 mm long, lobes homomorphic, lancelinear to linear, 5–9 mm long, abaxially pubescent with glandular and eglandular trichomes. Corolla dark red, 35–38 mm long, externally pubescent with eglandular and stipitate glandular trichomes, tube 9–20 mm long, lips 16–27 mm long. Stamens inserted near base of corolla tube, 27–30 mm long, thecae of a pair conspicuously unequal in size, parallel to subperpendicular to one another, glabrous, lacking basal appendages. Capsule (based on extralimital specimens from tropical America) 9–11 mm long, externally pubescent with erect eglandular trichomes and sessile to subsessile glandular trichomes; seeds 2.5–3 × 2.7–3 mm, surface smooth, lacking trichomes.

1a. Annuals; leaf blades 1.4–2.6 × longer than wide; calyx 2.3–3 mm long, lobes heteromorphic (posterior lobe ½ or less as long as others); corolla 2.6–3 mm long........................................................................ J. tenella (Nees) T. Anders.

1b. Perennials; leaf blades 2.6–4.2 × longer than wide; calyx 3–10 mm long, lobes homomorphic or nearly so; corolla 7.5–38 mm long........................................... 2

2a. Young stems and leaves glabrous; calyx 3–5.5 mm long; corolla 7.5–9 mm long; stamens 5 mm long, distal theca dorsally pubescent, proximal theca with a basal appendage 0.8 mm long............................................................ J. thomensis Lindau

2b. Young stems and leaves (on major veins) pubescent; calyx 6–10 mm long; corolla 35–38 mm long; stamens 27–30 mm long, both thecae of a pair glabrous and lacking basal appendages.............................................................. J. secunda Vahl

Figures

FIGURE 3 Miscellaneous vascular plants. Psilotum nudum (top), fertile plants on base of coconut palm (Daniel & Shevock 12035). Sciaphila ledermannii (bottom left), fertile plant (Daniel et al. 12085, photo by M. Nadel). Sciaphila ledermannii (bottom center), fertile plant (Daniel et al. 12084, photo by M. Nadel). Justicia secunda (bottom right), inflorescence with flowers (photo and copyright: C. Feuillet, CC BY-NC, used with permission), taken in French Guiana.