Argyreia hookeri C.B. Clarke

P. R., Lawand & Shimpale, V. B., 2024, Revision of the genus Argyreia (Convolvulaceae) from India, Rheedea 34 (5), pp. 337-396 : 364-365

16. Argyreia hookeri C.B. Clarke in Hook.f., Fl. Brit. India 4: 185. 1883. Rivea hookeri (C.B.

Clarke) Hallier f., Bull. Herb. Boissier 7: 60. 1899.

Argyreia populifolia sensu Choisy, A.P. de Candolle ,

Prodr. 9: 329. 1845. Lectotype: (designated by

Shalini, Lakshminarasimhan & Arisdason, 2017:

174): INDIA. Sikkim Himalaya , alt. 1–4000 ft ,

s.d., J.D. Hooker s.n. (K0001801783, image!).

Sikkim, Sikkim Himalaya, 4000 m, s.d., J.D. Hooker (K [K000830585 digital image!]; Isolecto

K ([K000830586, K000830588, K001081783,

K001081784 digital images!)], P (P00584821,

P00584822 digital images!]). Fig. 6j–m

A woody climber; older stems woody, glabrous or remotely hairy, younger stems white hairy, green, terete. Leaf lamina widely ovate to orbicular, 10–18 × 8–14 cm, apex abruptly acuminate, base deeply cordate, lobes rounded; secondary veins 9–11 pairs, depressed above, conspicuously raised beneath, sparsely hairy adaxially, densely white sericeous hairy adaxially, hair density more on veins, juvenile folded leaves possess shiny silky hairs; petiole 8–12 cm long, shorter than the peduncle, terete, not grooved, green, white hairy. Inflorescence axillary cyme, dichotomously branched, loosely arranged 6-15 flowered, peduncle white hairy, green, terete, 12–22 cm long, usually longer than the petiole. Flower pedicellate, bracteate; inflorescence bract (outer bract) leafy, petioled, 3–3.5 cm long, reticulately veined, hairy like leaf, flower bracts 2, 1–1.5 cm, caducous, lance-ovate, oblong-linear, apex acute, white tomentose outer, strigulose inner. Sepals 5, green, subequal, c. 1 cm long, outer two have reclined upper half, apex narrowly acute, glabrous inner, white strigose outer. Corolla infundibuliform, rose pink colored, 5–6 cm long and same across; tube c. 1 cm wide, dark purple inside, hairy on midpetaline bands; corolla lobes twisted in bud. Stamens 5, inserted to 0.5 cm above the tube, included, raised up to half of corolla tube; filaments white, dilated and glandular hairy at base; anthers 4–5 mm long. Ovary pale green; style white, 2.5–3.5 cm long; stigma biglobose, white. Berries fleshy, yellow.

Flowering & Fruiting: Flowering from late August to October and fruiting from November to January.

Habitat: This species is found at 3000 to 6000 ft. altitude; plants climbs up to a height of 5 to 7 ft. along the forest roads.

Distribution: India (Meghalaya, Mizoram, Sikkim, West Bengal), Nepal, Indonesia, Myanmar and Thailand.

Etymology: This species is named after the eminent botanist Sir Joseph Dalton Hooker.

Specimens examined: INDIA, Meghalaya, Khasi and Jaintia Hills, Mytang Valley , 20.01.1916 ,

Upendranath Kanjilal 6567 (ASSAM). Mizoram, Dampa Tiger Reserve, Lallen , 12.12.2006, N. Odyuo

113629 (ASSAM); Nokrek Biosphere Reserve ,

Near Sisubibra village , 16.10.2007, V. K. Singh &

Bikram Singh 116739 (ASSAM); Aizawl, West

Phaileng, 8.10. 2018, P. R . Lawand 014 (NCK);

Aizawl, Aizawl City, 08.10.2018, P. R. Lawand 043

(NCK). Sikkim, 1895, G . M . Gammie s.n. ( BSI); East Sikkim, Baghey Khola , 13.11.1998, S . S. Dash 20928

(BSHC); South District , Ratey Pani, 11.09.1981, B .

Krishna 1771 (BSHC); North Sikkim, Right Flank,

Dikchu, 13.12.1997, B. K . Shukla 20315 (BSHC);

West Sikkim, Tashiding, 11.12.1994, G. P. Sinha & S. Pradhan 15279 ( BSHC); East Sikkim, Saramsa ,

23.08.1980, P. K. Hajra 593 ( BSHC); East Sikkim ,

Reshi Khola, 10.12.1980, P. Chakraborty 1099

(BSHC). West Bengal, Kalimpong , 08.08.1997, P . Sinha & S. S . Dash 17282 ( BSHC); Jalpaiguri

District, Poro Buxa Division, 22.11.1975, J. K. Sikdar

838 (CAL); Darjeeling, on the way to Bagrakote,

13.10.2018, P. R . Lawand 044 (NCK).

Vernacular names: Hooker’s Morning Glory (English), Suntiki (Darjeeling), Tille-kumau-blang (Meghalaya).

Notes: The species is similar to Argyreia boseana Santapau & Patel in having approximately similar climbing height, widely ovate-orbicular cordate leaves, and flower size and shape. However, A. hookeri is distinct in having white indumentum all over, lance-ovate, oblong, caducous bracts, apically acute and reclined sepals, and smaller sized berries.

Clarke (1883) described Argyreia hookeri as distinct from A. populifolia sensu Choisy , noting clear differences such as whitish, hairy leaves, a different number of secondary veins, lance-ovate, oblong, caducous bracts, and white, strigose sepals. Although A. hookeri has been reported in regional and state floras from Maharashtra and Karnataka, these reports are erroneous. The species is actually restricted to the high-altitude regions of NorthEast India (Lawand & Shimpale, 2020).

Figures

Fig. 6. Argyreia FulgenS Choisy (a-d): a. Habit; b. Fruiting twig; c. Leaf showing gland in enlarge view; d. Sepals. Argyreia hirSuta Wight & Arn. (e-i): e. Habit; f. Inflorescence;g & h. Bracts; i. Sepals. Argyreia hOOkeri C.B. Clarke (j-m): j. Habit; k. Inflorescence; l. Bracts; m. Sepals.