I have been looking over Obermeyer's work and am completely satisfied
that "D. coccicaulis" is _D.natalensis_. My reasons are:
1)I harvested seed which was fusiform (spindle-shaped). This, and a
few other obvious eliminations, reduced the candidates to _D.aliciae_
and _D.natalensis_, as I think is the concensus anyway.
2)In Obermeyer's key, he writes that _D.aliciae_ is compact and *flat*,
with old leaves persisting. In contrast, _D.natalensis_ has a lax habit
with old leaves not long persistent. "D.coccicaulis" has a lax (not flat)
rosette, and old leaves can easily be pulled off the plant, while dead
leaves of _D.aliciae_ are more firmly implanted.
3)Last (and possibly least because it is not in the key but only in
the species descriptions), the stipules of _D.aliciae_ are described as
3-cleft, the middle lobe being the largest, while the stipules of
_D.natalensis_ are auriculate below, fimbriate above. Again the
plant "D. coccicaulis" matches _D.natalensis_.
So based on criteria 2, and 3, _D.natalensis_ wins out (at least for my
plants). There are not even any characteristics which argue against
_D.natalensis_, so at least to me this seems cut and dried, unless we
are dealing with a new species.
B