I original thought cucumber because of the leaves but if it's not that then idk, something in the squash family I'd guess. I don't believe you need multiple plants, in fact that reminds me I've read where people will plant one plant which produces enough for a small family as long as there is pollination from one flower to another on the same plant, although cross-pollinating from other plants/species of squash fam.will make the fruits better and stronger (from what I hear) but if you want 'pure seeds' hand pollination from flower to flower on the same plant will ensure this... I grow alot of veggies and such and I believe the only plant I have an issue with having to need two plants are my kiwi's a male and female. This info may be wrong I'm just talkin here ya know, goin off of memory (i think lol)