Discussion
The degree of variation in morphology, the structure of the trichomes
and fruits, and the kinds of hair are important characteristics in the
taxonomy of angiosperms. Drude (1898), Heywood and Dakshni (1971), Nasir
(1972), Arora (1976) and Pimenov et al. (2019) have all investigated
these characteristics, including the stylopodium, the number of
sectretory ducts in the mericarps, and the main and secondary valleculae
vittae. Micromorphological research has revealed that Psammogetonspecies differ noticeably from one another. When Rechinger awarded the
designation of holotype to the specimens kept in the herbarium W, he
established that Wagenitz’s identification of Psammogeton
canescens (DC.) Vatke subsp. cabulicus Wagenitz was accurate
(1982). The type specimens were gathered in Bagrami, which is close to
Kabul. In 1980, Nasir changed the name of this subspecies toPsammogeton cabulicus (Wagenitz) Nasir, giving it the status of a
species. In my opinion, Psammogeton cabulicus described by Nasir
is strikingly dissimilar from the Psammogeton canescens subsp.cabulicus Wagenitz described earlier. There is either error in
keeping P. canescens subsp. cabulicus as synonym underP. cabulicus (Wagenitz) Nasir as confirmed through the
specimens undertaken to study by authors. Perhaps this is the main
reason that these taxa remained unresolved so long without knowing the
current status of these taxa and data available related to these taxa
being insufficient. The identity of the species P. cabulicus(Wagenitz) is in fact different, therefore combination as given by Nasir
misidentified, therefore unacceptable. Furthermore, the illustration of
these two taxa are so different from each other that these cannot be
treated as same. The authors urge that holotype of P. canescenssubsp. cabulicus should not be placed under synonym underP. cabulicus (Wagenitz) Nasir since P. canescens subsp.cabulicus is quite distinct supported by taxonomic characters.