I think these are called grapenuts LOL or perhaps more commonly, false seed pods.
Apparently parthenogenesis can be caused by a calcium spike. So maybe too much Ca, or some environmental condition causing a flux in the ratio of mobile/non-mobile elements. Too much light or heat might be able to express it, or it could be lacking some enzyme genetically. I think it has a heavy genetic influence regardless of environment.
What was the strain? A sativa? These grapenuts are something I look for when selecting cuts. Guessing this plant was from seed.
Edited to add that Ed Rosenthal says parthenogenesis does not exist in cannabis, but I think people have different definitions. One that says a fully developed, virile seed must form for it to count as parthenogenesis, and another where any amount of embryonic cell division counts.