This does seem to fit Sagina and the obvious species is S.saginoides (L.) Karst. which was called S.procumbens in FBI and this is what Collet

named it in 'Flora Simlensis' - remarking it was found at Shimla and Narkunda on gravell walks and road-sides being the same as 'Pearlwort' in Britain.

However, this is where it gets more complicated.

Stewart listed the plant as S.saginoides with S.procumbens of FBI non. L as a synonym i.e. S.procumbens L. - the 'Procumbent Pearlwort' being a separate species. He recorded as common in Pakistan & Kashmir from 1500-4200m incl, Ladakh.

Both are accepted names and we have both in the UK. S.procumbens is common throughout the UK in paths, lawns, ditch-sides & short turf - it is even found just 50 metres from where I type in gaps in pavement. Whereas S.saginoides is a rare arctic-alpine plant of barish ground and rock ledges on mountains in Scotland.

Makes me wonder if the two separate species might not have been mixed up in the past?  Collet certainly thought they were the same species but thata is not the case.  Interestingly the 'Scottish Pearlwort' is recognised which is a hybrid between the two species!

In the UK (whether this applies in India I do not know) they can be separated by the usually 4-merous flowers & 4 stamens with petals minute or 0 in S.procumbens (I certainly remember struggling to detect any petals in a specimen from my road even with a hand lens) whereas the flowers of S.saginoides  are usually 5-merous, sometimes 4-merous, stamens 10, rarely 8, petals +/- obvious and generally a more upright plant.

Collet describes petals & sepals as 4 or 5!  Flowers very small, white. Stamens 4 or 5. 

As to the single image taken at Narkund (please, please take more than one shot per plant, several, as explained) - there are only capsules to be seen, though it appears there are 5 sepals.  Would the serious botanists amongst you look out for this plant on future trips to Narkanda or Simla or presumably lots of other places and with the aid of the hand lenses I am encouraging everyone to carry with them when looking at and photographing flowers, please check the number of stamens and how distinct the petals are on future occasions.

Perhaps both species occur in the hills and mountains of India with the habitat helping to distinguish between them, rather than one?

In the UK it is easy. Unless one is in the mountains of Scotland then S.saginoides is not a possibility. But this level of familiarity with our flora is a result of thousands of active field botanists exploring all over the Britain over a period of 2-3 centuries.

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Please find a few more pics of the same individual, though I believe this herb was in post-flowering stage. Place Narkanda, Himachal Pradesh, October 23, 2016. I cannot say if they will help to conclude the id.. Attachments (4)

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