Argyreia coonoorensis W.W.Sm. & Ramaswami, Rec. Bot. Surv.

P. R., Lawand & Shimpale, V. B., 2024, Revision of the genus Argyreia (Convolvulaceae) from India, Rheedea 34 (5), pp. 337-396 : 352-354

9. Argyreia coonoorensis W.W.Sm. & Ramaswami, Rec. Bot. Surv. India 6: 30. 1914. Type: INDIA, Tamil Nadu, Coonoor, Nilgiris , 6000 ft., November–December 1910, Meebold 12397 (holo K [ K000830696 digital image!]). Fig. 4f–h

A profuse climber or occasional prostrate shrub, almost all plant parts exude milky latex if cut. Stem older terete, glabrous, semiwoody, young purple, brown densely hispid, terete. Leaves petiolate; petiole 5–10 cm long, petiole of young leaves longer than peduncle, while that of mature leaves equaling or shorter than peduncle, brown hispid, very shallowly grooved adaxially; leaf lamina 17– 22 × 15–20 cm, widely ovate, base cordate, lobes rounded, apex acute, densely hairy on both the surfaces, brown hispid and pale green beneath, densely strigose adaxially, secondary veins 13– 14 pairs, raised to lower surface. Inflorescence axillary cyme, dichotomously branched, 5–10 flowered; peduncle 10–22 cm long, densely brown tomentose. Bracts outer, leafy, petiolate, 3–3.5 × c. 1 cm, lance-ovate, reticulately veined, hairy like leaf, inner bracts 2, unequal, 2–2.5 cm long, narrowly oblong, densely brown hispid outer, strigose inner, single veined, prominent on outer side. Sepals 5, equal, c. 1 cm long, ovate, apex acute or shortly apiculate, outer two narrow than inner, strigose outer, except on overlapped portions, glabrous inner, enlarges in fruit, persistent. Corolla infundibuliform, rose pink, throat dark purple, 5–6 cm long and 4–6 cm across, hairy on midpetaline bands, corolla limb shallowly lobed. Stamen 5, included in corolla tube, unequal 2 long, c. 3 cm, 3 short- 2.5–3 cm long; anther pink, 4–5 mm long; filaments dilated and glandular hairy at base. Ovary pale green, glabrous; style 1, c. 1 cm long, filiform; stigma biglobose, papillate, pink. Berries globose, 1–1.5 cm diameter, yellow. Seeds 2-4 per fruit, trigonal in shape, with visible hilum, white in color.

Flowering & Fruiting: Flowering from October to December and fruiting from late December to February.

Habitat: The species is locally abundant in Coonoor, Nilgiris, flourishes vigorously in cool climate, at the altitude 2100–2300 m.

Distribution: The species is endemic to India: Tamil Nadu.

Etymology: The specific epithet ‘coonoorensis’ designates to its type locality, Coonoor (Tamil Nadu).

Specimens examined: INDIA, Tamil Nadu, Nilgiris District, Coonoor , 1793 m, s.d., R. Sasi

8232 (Bharathiar University Herbarium); Nilgiris

District, Coonoor, Lovedale point, 25.11.2017,

P.R. Lawand 007 (NCK); Nilgiris District, Kil

Kotagiri, 25.11.2017, P. R . Lawand 034 (NCK);

Nilgiris District , Ooty, way to Kodanadu view point, 25.11.2017, P. R . Lawand 035 ( NCK) .

Conservation status: The species is only known from Nilgiri district of Tamil Nadu. Being endemic to this region, the species is under significant threat due to habitat destruction caused by land conversion for tea cultivation. Its populations are fragmented, with each observed population comprising fewer than 1,000 mature, reproducing individuals. Based on the IUCN (2024) guidelines, the species qualifies for Vulnerable (VU) status under criteria B1 and B2.

Notes: In the protologue, the species is noted to resemble Argyreia hirsuta Wight & Arn. and Argyreia pilosa Wight & Arn. However , morphologically, Argyreia coonoorensis closely resembles A. hirsuta in several traits, including leaf shape, the relative lengths of the petiole and peduncle, inflorescence architecture, bract shape, sepal shape, and fruit size and color. The primary distinguishing features of A. coonoorensis are its dense, long indumentum covering the entire plant and the presence of milky latex. Given these similarities, we hypothesize that A. coonoorensis could be a high-altitude variant of A. hirsuta . However, further studies, particularly molecular analyses, are necessary to resolve its taxonomic status conclusively.

Figures

Fig. 4. Argyreia CapitiFOrmiS (Poir.) Ooststr.(a-e): a. Flowering twig;b. Flower front view;c. Split open corolla hairy inside (in inset); d. Bracts, e. Sepals. Argyreia COOnOOrenSiS W.W. Sm.& Ramaswami (f-h): f. Flowering twig; g. Bracts;h. Sepals. Argyreia Cuneata Ker-Gawl.(i-l): i. Habit; j. Leaf; k. Open flower showing stamens;l. Fruiting twig.