Torenia leucosiphon Alston (1931: 212)

Prasad, Mangavayal Govindan & Sunojkumar, Purayidathkandy, 2015, Taxonomic identity of Torenia leucosiphon (Linderniaceae) and its resurrection from the synonymy of Torenia travancorica, Phytotaxa 219 (2), pp. 144-154 : 148

Torenia leucosiphon Alston (1931: 212) ( Figs. 1 & 2 )

Lectotype (designated here): ─ SRI LANKA. Bambara botuva, Pasdun Korale, June 1883, s.n. ( PDA!).

= Torenia asiatica var. parviflora Hooker (1884: 277)

[ Torenia asiatica sensu Thwaites (1864: 219) non Linnaeus (1753: 619) pro parte; Torenia asiatica sensu Trimen (1895: 249) non Linn.]

Annual diffuse herb, rooting from basal nodes, spreads about 50–80 cm. Stem 4-angled, profusely branched, glabrous except slightly hairy nodes, internodes up to 15 cm long, shallowly 4 grooved. Leaves simple, opposite, decussate; petiole up to 20 mm long, glabrous, with or without a purplish tinge; lamina 3.0–5.0 × 2.0–3.0 cm, broadly ovatetriangular, pinnately veined, glabrous, base truncate, apex acute-less acuminate, margins serrate- crenate. Flowers in clusters of 2–4 or solitary on leaf axils; pedicels up to 6 cm long, quadrangular, minutely hairy on angles, deflexed in fruit. Calyx oblong, 18–20 × 5.0–6.0 mm, bilipped, distinctly 5-keeled/ribbed, glabrous; upper lip 14–16 × 5.0– 6.0 mm, 3-lobed at apex, lobes lanceolate, about 2.5 mm long; lower lip 14–16 × 5.0–6.0 mm, 2-lobed at apex, lobes deeper than upper ones, about 5 mm long, lanceolate. Corolla bilipped; tube bright yellow or white, 22–24 × 8.0– 10 mm, glabrous; upper lip 10–12 × 12–14 mm, broadly ovate-orbicular, deep blue, rounded at apex; lower lip distinctly 3-lobed, lobes 6.0–8.0 × 10–12 mm, pale blue with deep violet margins, apex rounded, glabrous. Stamens 4, didynamous; posterior filaments shorter than anterior ones, 3 mm long, glabrous; anterior filaments longer, about 10 mm long, bend towards upper lip, distinctly appendaged at base; appendage about 4 mm long, straight, deep violet blue with numerous sessile glands; anthers coherent, 3.5–4.0 × 0.8–1.0 mm, pale bluish-white, bi-thecus, lobes equal, ovate-acute, longitudinally splits open. Ovary oblong, 4.0–5.0 × 1.0–2.0 mm, glabrous except slightly scabrous bend apex, placed on a hypogynous disc, disc forms a complete ring at the base of ovary, 1 × 2 mm, creamy white, glabrous; style 2–2.2 cm long, pale violet, glabrous; stigma bilamellate. Fruit oblong, 13–15 × 1.5–2 mm, minutely pubescent at apex, completely included in the hard fibrous fruiting calyx. Seeds many, minute, 0.4–0.5 × 0.4–0.5 mm, yellowish, foveolate, bothrospermous.

Phenology:— Flowering and fruiting was observed during July to December.

Distribution and habitat:— Its occurrence is restricted to Travancore region of Southern Peninsular India and Sri Lanka (former Ceylon) ( Fig.5 ). It growsell in marshy areas in evergreen forests and nearby undisturbed areas.

Additional specimens examined:— INDIA, Kerala: Villumalai, Near the huts of hill tribes, 13 February 1961, Subrahmanian 76681 ( BSI!) ; Thiruvananthapuram District, Bonaccord , near tea factory, 7 October 2014, Prasad 142331 (CALI) ; Thiruvananthapuram District, Bonaccord , 9 October 2014, Prasad 142335 (CALI) ; Thiruvananthapuram District, Kottur Researve Forest , 150 m, 8 April 1973, Joseph 44094 ( MH!) ; Travancore , 25 September 1893, s.n. 35986 ( MH!) ; Idukki District, Kattappana, 1000 Mts , 11 November 1981, Ramanujam 72448 ( MH!) ; Idukki District, Thekkadi , 3000 ft., 26 September 1925, Jacob 17780 ( MH!) ; Idukki District, Idamalayar , 25 September 1980, Nambiar 1278 ( KFRI!) ; Thrissur District, Mudalmala , ± 200 m, 5 October 1987, Sasidharan 4656 ( KFRI!) ; Idukki District, Periyar tiger Reserve , Koruthode , 350 m, 18 January 1997, Augustine 17130 ( CALI!) ; Idukki District, Periyar Tiger Reserve, Anchuruli , 12 November 1994, Augustine 14294 (CALI) ; Thiruvananthapuram District, Bonaccord , 21 December 1987, Mohanan 9010 ( CALI!) . SRI LANKA. Vellakanda forest, Panilla , December 1893, sine coll. s.n. ( PDA!) ; sine coll. C.P. 2032 (PDA!).

Figures

FIGURE 1. Torenia leucosiphon. A. Flowering twig; B. Leaf; C. Flower; D. Calyx; E. Corolla; F. Corolla split open; G. Gynoecium; H. Fruit; I. Seed. (All draws from Prasad 142331 by M.G. Prasad).

FIGURE 2. Torenia leucosiphon. A, B. Flowering twig; C, D. Flower; E. Calyx; F. Corolla; G. Corolla split open; H. Posterior stamens; I. Anterior stamens; J. Staminal appendage; K. Gynoecium; L. Ovary; M. Apical portion of ovary; N. Stigma; O. Fruit; P. Seed.

FIGURE 5. A. General map of India and Sri Lanka; B. Distribution of T. leucosiphon (▲) and T. travancorica (●).