What's in the Name?

I got some seeds and on the envelope it said:
Salvia sp.  

Salvia officinalis = Sage with herbal uses growing in my potager


What does sp. stand for? I found this very useful article by Susan Mahr about Botanical and Latin names. I learned that:

Unspecified or unknown specie in the genus of for instance Salvia would be written as Salvia sp. To signify more than one species in the genus,

To Taste Tomas Edison or Not...

...that is the question.

'Dahlia blooms are showy, but it’s their edible tubers that make them an excellent addition to kitchen gardens.'  ROB CARDILLO

 
  To those of you who have asked what colorful and somewhat showy flower I got in my hand on my Facebook avatar it's a Dahlia. Dahlia 'Thomas Edison'. I know that the native americans (Aztec) used the dahlia tubers for food, but I have not