[Fleur Pavlidis]

Could the experts please confirm or otherwise that this is Hymenocallis acutifolia?

[Alisdair]

Yes, You're right, Fleur - lovely!
Growing in your garden?

[Fleur Pavlidis]

No, by Sally's front door. It produced plenty of seed which is still green. Any idea if it should be sown now or if the pods should be allowed to dry out?

[ezeiza]

When the seeds are ready they will fall to the ground. Sow half buried in a well drained mix but do not water too much: the seed has enough water to produce a complete new bulb. In some species the new bulb will produce leaves at  once in others the bulb will remain dormant in the mix and only sprout the following spring.

Can not produce an ID from seeing the flowers alone. This is a complex genus with most species misnamed in the trade.

[Alisdair]

Fleur, Sorry about that, Alberto's right really. And I'm not "expert" like he is! But to put it another way, the flower of Sally's plant looks from the photo like what people who grow it in Europe call H. acutifolia - though as Alberto says they may be incorrect.   

[ezeiza]

Not quite that, only that it is a difficult genus. Species are good but the fact that material in the trade is misnamed adds to the general chaos. The following is relevant

Origin (of course)
foliage is petioled, lorate or linear?
foliage is greyish or dark fresh green
(habit) foliage is erect or curved?
Lastly, the flowers, that all look rather similar except for dimensions

I once mixed the labels of those species we grow and it was a real problem to reassign them.

Something similar happens with galanthi