Recently I ordered some seeds from Vlado and recevied a substitute as the ones I wanted were sold out. The ones I wanted were Mamm. senilis. The ones I got as subs were Mamm. senilis f. RS 801EI Salto. What do these extra parts to the name mean? What have I actually got here?

The latter part of the name refers to a location or locality where the seed was collected. As for yours I really don't have a clue, the "Ei Salto" section would normally refer to a town or place.

Hope this helps a little. For the most part it will be virtually identical

Thanks , so in terms of naming it do you need to keep quoting this extra information? I think, looking at it again, the last part should read El Salto if it's meant to be a locality name.

Ahhhhhhh... I found some extra information based on your advice that it was a locality reference... RS refers to the name of the collector which I think is Roman Stanik, 801 is a collection number and El Salto is a place in Mexico. I got this from this website: http://ralph.cs.cf.ac.uk/Cacti/acronym.html . I'm not sure but I think the 'f' is meant to be cf. which is a nomenclature standard I am familiar with.

This refers to this particular batch of seed: http://ralph.cs.cf.ac.uk/Cacti/fieldno.php?FieldNo=rs801

I think the f. in this case just means "forma" or form...But it is handy to be able to google map a town or locality and know where your plant came from...

Ralph Martin has done us all a great service getting that info all in one place...

So, until the taxonomists get to it and decide it is a different and unique species () , it should be labelled in full as shown above then (assuming I can get the seeds to germinate ) and not just Mamm. senillis?