Allotypes in botany

[Wayt Thomas]

Whether plant or animal, the function of a type is to link the
scientific name to a specimen.  As soon as other specimens are
identified by a given name, they are, in the _opinion_ of the
identifier, being considered taxonomically equivalent to the type
specimen of that name.  This process of assigning other specimens to
that name enriches the _circumscription_ of that taxon.  This is true
whether the additional specimens are obviously identical to the type
or markedly different as in the case of different sex specimens or
different life cycle stages.

Assigning additional "types" to a name would change the type concept
from the (supposedly) simple one of linking a name to a specimen to
one that also makes permanent some aspect of the circumscription of
the taxon in question.  The circumscription of a taxon is much more
likely to be fluid and subject to change.  Even though the linking of
dimorphic sexes in animals or dioecious plants, or the linking of
wildly differing fungal and algal life cycle stages, can be important
discoveries, they do not constitute the kind of discovery that
warrants additional typification of a name -- they are, after all,
hypothesized relationships.

Besides types, many kinds of specimens in a collection can be
extremely important.  As mentioned previously, these too can be
labelled in distinctive ways so that they stand out in the collection.

Wayt Thomas
The New York Botanical Garden