Andrographis elongata

Andrographis elongata (Vahl) T. Anders., J. Linn. Soc., Bot. 9: 502 1867. (syn: Cryptophragmium cordifolium Nees; Cryptophragmium elongatum Nees; Justicia clandestina Russell ex Wall.; Justicia cordifolia B.Heyne ex Wall.; Justicia elongata Vahl);
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S. India as per POWO;
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Common name: Long Raceme False-Waterwillow
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Erect herbs up to 2 m long with divaricate branches; stem stout, tetragonous, pubescent. Leaves opposite, 1.5-3 x .5-1.5 cm, ovate, acute, rounded and then decurrent at base, slightly pubescent; lateral veins 3-4 pairs; petioles less than .5 cm long. Racemes axillary, branches elongated, peduncle up to 12 cm long pubescent; flowers distant; pedicels very short or 0. Calyx 5-lobed, lobes very slender, 2-4 mm long, glandular pubescent. Corolla white, apparently pink, obscurely 2-lobed, 3-8 x 3-5 mm across, glandular hairy without. Stamens 2, to 1.3 cm long, puberulous, 1.4 cm; anthers 2 mm long, glabrous. Ovary oblong, 1 cm long, puberulous; style 1.2 cm long, hairy. Capsule 1.5-2 x .1-.2 cm long, oblong, compressed, minutely hairy acute. seeds 8-12, c. 1 mm long, ovoid, pale brown.
Flowering and fruiting: March-May
Moist deciduous forests
(Attributions: Dr. N Sasidharan (Dr. B P Pal Fellow), Kerala Forest Research Institute, Peechi as per India Biodiversity Portal)
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Swamy/New series/ID/55 – Acanthaceae: 7 images.
I am forwarding herewith a set of photographs received from Chennai. Growing on a farm land. Please ID the plant. The flowers have similarity to Andrographis species.