Trichosanthes tricuspidata Lour.

Pradheep, K., John, K. Joseph, Singh, P. K., Rathi, R. S. & Pandey, A., 2021, A new subspecies and new records of Trichosanthes (Cucurbitaceae) for India, and notes on T. khasiana, Blumea 65 (3), pp. 233-243 : 237-240

2. Trichosanthes tricuspidata Lour. — Fig. 3f–h ; Map 2

Trichosanthes tricuspidata Lour.(1790) 723; Duyfjes & Pruesapan (2004) 98; W.J. de Wilde & Duyfjes (2008) 535; (2010) 308; Lu Q.Huang & C.Jeffrey (2011) 43. — Neotype (designated by Keraudren-Aymonin 1975): J. & M.S. Clemens 3267 (neo P; isoneo BM), Vietnam, Quang Nam, Da Nang, May–July 1927.

Dioecious perennial climber, 5–15 m long. Stems glabrescent at early stage, 2–4 mm diam; young shoots reddish or green, striate; probracts (broadly) obovate, 5–7 by 3–5 mm, margin entire, with green glands; tendrils 2- or 3-branched. Leaves: petiole 4–6 cm long; blade broadly ovate or orbicular in outline, 7–10 by 5.5–9.5 cm, usually 3-cusped, cusps divaricate/ divergent, membranous, (sub)glabrous adaxially, glabrous abaxially, the central cusp ± triangular, to 7 cm long, the apex of all cusps acuminate(-caudate), the margin (sub)entire or wavy with small dentations, glands few, very small. Staminate inflorescence 8–12(–15) cm long, peduncle 4–6 cm long, c. 2 mm thick; rachis with 5–10 flowers; bracts obovate-elliptic, 2–3.2 by 1.5–2 cm, with conspicuous glands, obscurely dentate, 3–5 mm deep. Staminate and pistillate flowers not seen. Fruits ± ovoid, 5–5.5 by c. 4 cm; pedicel 1–2 cm long; exocarp bright red, smooth; mesocarp yellow, 8–9 mm thick; pulp greenish black. Seeds dark brown, compressed, obovate-elliptic or oblong, c. 8 by 4.5–5 by c. 2 mm, often with inconspicuous longitudinal midline, edge almost rounded, entire.

Distribution — Bangladesh, China, India (Andaman & Nicobar Islands), Myanmar, Thailand, Vietnam, West Malesia.

Habitat & Ecology — Roadside thickets, along forest openings; over rocks; at 0–350 m altitude. Flowering: May to September; fruiting: October to January.

Notes — 1. Most of the Indian literature from 1980s onwards follows Jeffrey (1980), who treated T. bracteata as synonym of T. tricuspidata , therefore the name T. tricuspidata was invariably used in place of T. bracteata . On the other hand, we consider them as distinct species in accordance with King (1898: 29), Rugayah & De Wilde (1997) and Pandey et al. (2016). However, we disagree with Pandey et al. (2016), who stated that India (incl. Andaman & Nicobar islands) has only T. bracteata , while T. tricuspidata occurs in Indochina and Malesia. Our study revealed that T. tricuspidata occurs in the Andaman & Nicobar islands. Renner & Pandey (2013) mentioned a doubtful distribution status of this species for West Bengal, based on T. tricuspidata var. strigosa Sunit Mitra & S.Bandyop. While the holotype of the latter (S. Bandyopadhyay 2904) was untraceable at CAL, its reported distribution as ‘throughout India’ revealed that this taxon corresponds to T. bracteata only.

2. The distinguishing features between T. bracteata and T. tricuspidata are given in Table 2. Pandey et al. (2016) distinguished T. bracteata from T. tricuspidata by using six characters. The characters, margin of pistillate calyx lobes with side lobes, (often) ellipsoid-shaped fruits, fruits with 10-longitudinal paler streaks and marginate seeds mentioned for T. bracteata are found to be untenable in our study. Ellipsoid fruits and streaks over the fruits were never met with T. bracteata , which is always (sub)globose, while converse of other characters are also found in the highly variable T. bracteata .

3. At juvenile stage, T. tricuspidata usually possesses 5–7- deeply lobed leaves, later on, gradually 3-lobed towards mature stage of plant growth.

4. After observing parallel variation in the contemporary poly- morphic species T. bracteata , we refrain from further classifying the variability within T. tricuspidata ; as the two subsp. ( subsp. tricuspidata and subsp. rotundata W.J.de Wilde & Duyfjes ) have overlapping distribution patterns and no good characters to distinguish them. Nevertheless, our collections match more towards subsp. rotundata owing to the round-edged seeds.

3. Trichosanthes wallichiana (Ser.) Wight subsp. subrosea (C.Y.Cheng & C.H.Yueh) K.Pradheep & K.J.John , comb. nov. — Fig. 3a–e ; Map 3

Trichosanthes subrosea C.Y.Cheng & C.H.Yueh in C.H. Yueh & C.Y. Cheng (1980) 349. — Type: T.T. Yu 19429 (holo PE; iso A,E, PE), China, Yunnan, Kiukiang Valley , Chiengen , 1700 m, 26 July 1938

Trichosanthes grandibracteata Kurz (1877) 98, 99. — Type: not indicated, untraceable. See note 2.

Trichosanthes tridentata C.Y.Cheng & C.H.Yueh in C.H.Yueh & C.Y.Cheng (1980) 349, syn. nov. — Type: C.Y. Cheng 73-04 (holo Paking Med. Col. conserv.; iso: K), China, Yunnan, Luxi Xian .

Trichosanthes wallichiana auct.non (Ser.) Wight:Grierson & D.G.Long (1991) 266; S.K. Chen (1995) 357; Lu Q.Huang & C.Jeffrey (2011) 41.

Medium, perennial, dioecious climber. Stems glabrous, sulcate-striate, 4-angled; shoot pinkish or green with a ring of pink hispid hairs around the node; probract caducous, rarely absent, broad lanceolate or spathulate, 2–3 cm long, margin pinkish bordered, laxly serrate, venation reticulate; tendrils 3-fid. Leaves: petiole 6–10 cm long, striate, often with short white or pink hispid hairs; blade cordate or suborbicular in outline, 15–20 cm long, thinly papery, 5–7-lobed to 4/5th, each lobe irregularly partite or sinuate; central lobe subrhombic or elliptic, to 18 cm long, abaxially pale green, adaxially deep green, both surfaces hispidose, margin dentate; glands small, mostly in leaf base. Staminate inflorescences occasionally in pairs, one early, single flowered, and the other bearing a raceme; raceme (20–)25–35(–38) cm long, striate, 4-angled, 10–15-flowered, peduncle 15–25 cm long, flower bud pinkish, clasped by calyx lobes, flowers fra- grant; bract obovate, 2.5–3 cm long, pale green, cucullate, glabrous, apex obtuse, basal half subentire, distal half irregularly lacerate, glands few. Staminate flowers: calyx segments narrowly lanceolate, (1.2–)1.5–2 by c. 0.5 cm, entire; calyx tube 7–8 cm long, striate, widens at 2/3rd towards the throat, hairs short, pink, glandular; corolla inner core yellowish, velvety; corolla lobes c. 2 by 1.5 cm, apex truncate, deep pink outside and pale pink inside or rarely snow-white, frills up to 4 cm long, thread-like, branching; stamens short of corolla rim, connate, c. 1 cm long, filament c. 0.5 cm long. Pistillate flowers: pedicel 1.5–2 cm long, often covered with pink glandular hairs; calyx tube c. 4 by 0.2–0.3 cm, gradually widening towards the throat, calyx and corolla as in staminate flower; ovary ovate-clavate, 1–1.2 by 0.35–0.4 cm, pink glandular hairy; style c. 2.5 cm long, stigma 3-lobed. Fruits: pedicel stout, 2–3(–4.5) cm long; exocarp orange-red, subglobose, rarely base slightly rostrate, 6–8.5 by 5.5–7.5 cm; pulp greenish black. Seeds greenish brown, 4-angled, 11–15 by 7–10 by 2.4–3 mm, lateral sides angular, prominently tridentate at the distal end.

Distribution — China (Xizang, Yunnan,? Guangxi), India (Arunachal Pradesh, Assam, Meghalaya, Nagaland and Manipur), Bhutan, Myanmar.

Habitat — Common amidst grasses on roadsides, bamboo forests and thickets at 900–1700 m altitude. Flowering: July, August; fruiting: September to November.

Notes — 1. The two subspecies of T. wallichiana differ mainly in seed characters, which have been summarised in Table 3. The importance of seed characters in distinguishing taxa in Trichosanthes is also stressed by Rugayah (1999) and Duyfjes & Pruesapan (2004). Since the type locality of T. wallichiana is from Nepal, collections from Nepal and adjoining Sikkim, Darjeeling and Kalimpong areas (of India), all exhibiting a distinct seed morphology, form the typical subspecies. While other areas, engrossing vast areas of northeast India, Myanmar, Bhutan and southwest China represent subsp. subrosea . Earlier reports of T. wallichiana subsp. wallichiana occurring in areas of India other than the northeast ( Chakravarty 1959, 1982, Renner & Pandey 2013), are based on misidentification of the variable T. bracteata .

2. In the protologue of T. grandibracteata ( Kurz 1877: 98, 99), Kurz did not cite any specific specimen or gathering but only the locality: “Ava, along the Irrawadi northwards from Mandalay; also Khakyen-hills east of Bhamo”. As there are no Trichosanthes collections from these areas, either collected by Kurz or earlier botanists, available in any of the herbaria, the name is difficult to interpret. Huang & Jeffrey (2011) synonymised T. tridentata with T. rubriflos Thorel ex Cayla. However , the isotype of T. tridentata (at K) has greenish brown angular seeds with 3 dents at the distal end, and these characters are typical of subsp. subrosea .

3. In Myanmar, T. wallichiana subsp. subrosea was collected from Seinghku Valley by F. Kingdon-Ward (http://bioportal. naturalis.nl/multimedia/L.4288886_0379698312/term=trichos anthes +subrosea &from=0 last accessed 08 December 2019), which adjoins the Indian state of Arunachal Pradesh. Presence of this taxon in Bhutan is established by the herbarium specimen housed at CAL (CAL0000060567) and on the au- thority of Grierson & Long (1991), who described the seeds of T. wallichiana as ‘squarish, 15–17 mm, 7 mm thick’. In the absence of any obvious dissimilarity in mountain landscapes between Sikkim and Bhutan, occurrence of subsp. wallichiana further in the western part of Bhutan and the midway areas of Tibet ( China) is in expected lines. Charles Jeffrey annotated the specimen GH00031967 (https://s3.amazonaws.com/ huhwebimages/7DAD1626178C4C0/type/full/31967.jpg last accessed 09 September 2019) as an isotype of T. khasiana ; however, its deeply lobed leaves with sinuate margin, staminate inflorescence with very long peduncle, flowers crowding at the top, and obovate bracts with subentire basal part at once identify it as subsp. subrosea . Pistillate flower characters of this taxon have been described for the first time.

4. Some of the field characters include the medium-sized (not robust) climbing nature, presence of a ring of pink hairs surrounding the nodes, staminate flowers and bracts congested at the top of the inflorescences, green-yellow bracts that never open wide, and the plant drying up very quickly at the time of cessation of fruiting.The tridentate nature of the seeds becomes increasingly strong towards the east longitude.

5. Jeffrey (1980) mentioned the fruits as ellipsoid, however, they are actually (sub)globose, sometimes with a slightly rostrate end. In the Flora of China, Huang & Jeffrey (2011) wrongly reported the flower colour of T. wallichiana as white, whereas it is actually pink.

Figures

Map 3 Distribution of Trichosanthes wallichiana (Ser.) Wight subsp. wallichiana and T. wallichiana (Ser.) Wight subsp. subrosea (C.Y.Cheng & C.H.Yueh) K.Pradheep & K.J.John in South Asia.

Fig. 3 Trichosanthes wallichiana (Ser.) Wight subsp.subrosea (C.Y.Cheng & C.H.Yueh) K.Pradheep & K.J.John.a.Pistillate flowering twig (note long probract); b. twig with immature fruit; c. staminate flowering twig (inset: distal part of staminate inflorescence showing fully-opened staminate flower); d. ripe fruit;e. longi- tudinal section of ripe fruit and seeds. — f–h. Trichosanthes tricuspidata Lour.f. Twig with ripe fruit;g. cross section of fruit;h. seeds. — Photos by K. Pradheep.