Dioscorea hamiltonii

Climber to at least 10 m. Tubers one per growing season, often with withering tuber of previous season, c. 0.4–1 by 7.5–12 cm, cylindric to clavate, vertically oriented, subtended by a woody crown. Indumentum sometimes present on young inflorescences, axes, stems and the veins of the leaf blade lower surface, hairs simple, 0.05–0.1 mm long. Stems 2–5 mm in diam., twining to the right, annual, unarmed, terete with shallow longitudinal ridges, usually drying a coppery colour in herbarium specimens. Leaves simple, opposite, sometimes subopposite or alternate toward base, blades narrowly to broadly ovate, in stem leaves always broadest above the point of petiole insertion, chartaceous to subcoriaceous, 7–9-veined, secondary venation prominent below, margins entire, base cordate, apex acuminate; petioles 2–8.5 cm long; cataphylls 2–2.5 by 2.5–3 mm, ovate to broadly ovate; bulbils and lateral nodal organs absent. Inflorescences pendent, axes copper-coloured like stem, tepals free, inserted on a discoid torus, fleshy in texture, with inner whorl tepals usually thicker than outer; male inflorescences spicate, simple or compound, compound inflorescences 1–2 per axil, simple/partial inflorescences 1–3(–4) per axil, peduncles 1.2–2.5 mm long, axes 0.8–2.7 cm long, flexuous; female inflorescences racemose, simple, 1–2 per axil. Male flowers with outer tepals 1.2–1.5 by 0.5–1 mm, ovate, inner tepals 1–1.2 by 0.7–0.9 mm, obovate, stamens 6. Female flowers on 1.1–2.5 mm long pedicels, and tepals 2.6–4.1 mm long (at least 2 times larger than males!). Capsules 19–25 by 38–43 mm. Seeds 6.5–7.5 by 7–7.5 mm, ovoid-lenticular, wings 19–21 by 17–19 mm, extending all around seed margin.

Dioscorea species

but which one. how does one know. chemical analysis of the proteins/ or cho or what? or otherwise how?
i’ll appreciate some definite modern papers if any esp for the steroid like chemical’s presence

I agree with …

From external view i think this species is Dioscorea hamiltonii

Perhaps yes, I do not know, please check-

Nepali name : बन तरुल Ban Tarul 

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References:
The Plant List Ver.1.1  WCSP  IPNI  e-monocot  Annotated checklist of Flowering plants of Nepal  India Biodiversity Portal  Wikipedia Indian Medicinal Plants: An Illustrated Dictionary By C.P. Khare (2008- Details)