Argyreia hookeri C.B.Clarke

P. R., Lawand & Shimpale, V. B., 2020, Notes on identity and distribution of Argyreia boseana and A. hookeri (Convolvulaceae) in India, Rheedea 30 (2), pp. 282-285 : 284-285

Argyreia hookeri C.B.Clarke in Hook.f., Fl. Brit. India 4: 185. 1883. Rivea hookeri (C.B.Clarke) Hallier f., Bull. Herb. Boiss. 7: 60. 1899. Lectotype (designated by Shalini et al., 2017): INDIA, Sikkim, Sikkim Himalaya , 4000 m, s.d., J. D. Hooker s.n. (K [ K001081783 digital image!]; isolecto K [ K001081784 , K000830585 , K000830586 , K000830588 digital images!], P [ P00584821 , P00584822 digital images!]).

Argyreia populifolia Choisy, Convolv. Orient. 32. 1834, p.p.; Kanjilal et al., Fl. Assam 3: 342. 1939; Balakr., Fl. Jowai 2: 328. 1983; Ghosh & Mallick, Fl. Darjeeling Himalaya 165. 2014; Mao et al., Checkl. Fl. Meghalaya 120. 2016. Fig. 1a 2-e2

A woody climber; older stems woody, glabrous or remotely hairy, younger stems white hairy, green. Lamina widely ovate to orbicular, 10–18 × 8–14 cm, apex abruptly acuminate, base deeply cordate, lobes round, secondary veins 9–11 pairs, depressed above, sparsely hairy adaxially, densely white sericeous abaxially, denser on veins, juvenile leaves with silky hairs; petioles 8–12 cm long, terete, not grooved, green, white strigose. Inflorescence loosely arranged, 6–15-flowered; peduncles 12–22 cm long, white appressed-strigose; inflorescence bracts (outer bract) leafy, stalk 3–3.5 cm long, reticulately veined, abaxially white sericeous. Flowers pedicellate; floral bracts 2, lance-ovate to oblong-linear, 1–1.5 cm long, caducous, white tomentose outside, strigulose within. Sepals subequal, c. 1 cm long, outer two with a reclined upper half, apex narrowly acute, glabrous within, strigose outside. Corolla rose-pink, 5–6 × 5–6 cm; tube dark purple within, hairy on midpetaline bands; corolla lobes twisted in bud. Stamens inserted, c. 0.5 cm above base of tube, included, raised up to half of corolla tube; filaments white, dilated and glandular hairy at base. Fruit a fleshy berry, yellow.

Flowering & fruiting: Flowering in July to October and fruiting in October to January.

Distribution: India, Indonesia, Myanmar, Nepal and Thailand.

Specimens examined: INDIA, Meghalaya, West Jaintia Hills district, Khasi and Jaintia Hills , Mytang Valley , 20.01.1916, U . Kanjilal 6567 ( ASSAM); West Garo Hills district, Nokrek National Park , near Sisubibra village , 16.10.2007, V. K . Singh & Bikram Singh 116739 ( ASSAM) . Mizoram, Aizawl district, Aizawl City , 08.10.2018, P. R . Lawand 043 ( SUK); Mamit district, Dampa Tiger Reserve , Lallen , 12.12.2006, N . Odyuo 113629 ( ASSAM); West Phaileng , 08.10.2018, P. R . Lawand 014 ( SUK) . Sikkim, East Sikkim district, 1895, G. M . Gammie s.n. ( BSI); Baghey Khola, 13.11.1998, S. S . Dash 20928; Saramsa , 23.08.1980, P. K . Hajra 593; Reshi Khola , 10.12.1980, P . Chakraborty 1099 ( BSHC); South Sikkim district, Ratey Pani , 11.09.1981, B . Krishna 1771 ( BHSC); North Sikkim district, Right Flank, Dikchu , 13.12.1997, B. K . Shukla 20315 ( BHSC); West Sikkim district, Tashiding , 11.12.1994, G. P . Sinha & S . Pradhan 15279 ( BHSC) . West Bengal, Darjeeling district, Darjeeling, on the way to Bagrakote , 13.10.2018, P. R . Lawand 044 ( SUK); Jalpaiguri district, Poro Buxa Div. , 22.11.1975, J. K . Sikdar 838 ( CAL); Kalimpong district, Kalimpong , 08.08.1997, P . Sinha & S. S . Dash 17282 ( BSHC) .

Notes: Argyreia hookeri is closely similar to A. boseana in having widely ovate to orbicular leaves, longer peduncles, few to many flowered inflorescence, rose-pink corolla and yellow fleshy berries. However, A. hookeri can be distinguished by its sparsely hairy adaxial and white tomentose abaxial leaf surfaces, 6–15-flowered, dichotomously branched cymes, lance-ovate caducous bracts and outwardly reflexed lance-ovate sepals with acute apex. In addition, both the species shows a disjunct distribution. Some additional morphological differences between these taxa are given in Table 1 and Figure 1 .

Based on extensive field surveys along the Western Ghats and after examining the herbarium specimens of Argyreia at AHMA, BLAT, BSI, CALI, DRC, MH and TBGT, it is concluded that A. hookeri does not occur in the Western Ghats. After careful scrutiny of our own collections and specimens at above mentioned herbaria, it is revealed that whatever specimens collected and identified as A. hookeri from the Western Ghats are actually belong to A. boseana . The original taxon identified erroneously as A. hookeri by Cooke (1908) was later described as A. boseana by Santapau and Patel (1958). The Cooke’s concept of A. hookeri was, however, followed by succeeding taxonomists ( Sharma et al., 1984; Venkanna & Das Das, 2001; Ramaswamy et al., 2001; Manikandan & Lakshminarasimhan, 2013; Nayar et al., 2014). Report on the occurrence of A. hookeri in Western Ghats is thus erroneous.

Figures

Fig. 1. CompariSon of Argyreia boSeana SantapaU & V.Patel (a1–e1) and Argyreia hookeri C.B.Clarke (a2–e2): a. Flowering twigS; b. Leaf–abaXial SUrfaCeS;c. InfloreSCenCeS;d. BraCtS; e. SepalS.