Unfortunately nothing is addressed in the Code in this regard. At least reproduction of the image of holotype should be made mandatory in the protologue. Anyway, when the type is not deposited as mentioned in the protologue, the original illustration should be selected as the lectotype after sufficient wait (say one year).

Historically, types were discovered and taken back to the discoverer's home institution usually for futher study by the collector and his collaborators. Maybe that is still to be expected and most desirable. Concentrations of types have been lost in the past. Brazil's National Museum held most of the Amazonian types. About 90% of its collections were destroyed by fire in 2018 Entire genera of related insects and perhaps higher taxonomic levels too were wiped out. Then there was Vavilov's agricultural wild type seed collection that was at risk when the former Soviet Union collapsed. https://www.latimes.com/archives/la-xpm-2003-apr-27-fg-seeds27-story.html It was at risk more than once due to a lack of understanding of its importance by those in charge of providing funding, combined with the scarcity of funding. It remains the largest collection ever made of wild seeds related to modern agricultural crops. Ruiz and Pavon, who headed the first official botanical collections by Spain in the New World lost all of their types twice, once in a warehouse fire, and once on a ship that sank at sea. Both times nearly all of their types were all in one place. This is why it is important to file isotypes of holotypes at more than one herbarium and not keep all holotypes together. Unfortunately, sometimes only a single good herbarium specimen exists. Recently a young plant biology undergraduate student told me he had been taught herbaria no longer require funding. He was taught that they can be destroyed after the specimens they contain have been scanned. Truly a lack of understanding. Much cannot be seen on most scans, and complete biochemical, genetic, and epigenetic testing of all specimens is neither economically or scientifically possible. Not enough money and too many unknowns. No other organisms are as well studied as Arabadopsis or humans, and still a lot is unknown about either of them. Soybeans have been studied extensively, with thousands of individuals of hundreds of varieties sequenced. Yet when David A. Lightfoot died, he did not consider the map of soybean genetics to be complete. I have digressed a little, but I think the point is, don't put all of the eggs in one basket, not any kind of basket.

Dear Miriam Kritzer Van Zant, you made a valid point. But I think I never said of keeping all the types at one place. Its just that holotypes should be harbored by one prime institution of the country and all other supportive types (Isotype, paratype, syntype, epitype, etc.) can be placed in the institution where research is be done or as per the wish of authors. So there is no chance of complete destruction. even in worst case scenario the holotype herbarium gets destroyed by any ways there will be other types to support the plant name. But think if all the holotypes are placed at one place their accessibility will be improved and there will be a check on unwanted publications. Isn't it so?

Holotypes and isotypes are not always of equal quality. Sometimes the person who found them needs direct access to both for an extended portion of their career, or might, if forced to give one up, be tempted to make the poorer specimen the holotype because they are required to relinquish it sooner. Sometimes there is no real isotype. I was sent one type for the same Andean Mirabilis spp. (Nyctaginaceae) from both the British Museum and Madrid. Which was the real one was in dispute, because of the aforementioned losses of the first types and because Pavon rewrote his memoirs of their collection trips three times, changing the order of events pertinent to Mirabilis spp. each time, there were no collection numbers in any ofhis three memoirs, and his widow sold part of his personal collection as it stood when he died, to the British Museum. Maybe the real type was in his home at the time. One of the types was just crushed material in a packet, but it may have been the true original which would make it the right holotype. I realize this kind of problem is not always an issue, or can be decided upon, though a future taxonomist may disagree with an earlier decision. There would still be the potential for safety problems even if only the holotypes were together. I think higher quality scans are in order for many families, and micrographs of tissue samples including multidirectional cross sections, showing all vascular arrangements including both node and internode tissue, for stems, branches, leaves, bark/epidermal tissue, wood arrangement for trees, seeds, fruits, flowers and all individual flower, seed, leaf and fruit structures, hair, gland and stomate patterns, etc. Scans often can't be blown up enough to see these things, not even their surfaces. They may also be packed together too tightly for visiblility on scans, or be hidden within other tissue, something only a taxonomist working on the taxonomy of the group should be disturbing at all. Not everyone scanning material is doing that. Chemical, genetic, and epigenetic information are still mostly to be determined. However, there are certainly virtual repositories for genetic information already. The morphological images could be kept in a central virtual herbarium. I'd still at this point rather that not all physical holotypes were put in one place. To be fair, if the one place could be guaranteed to be protected and well cared for in perpetuity, that would be great. Unfortunatley this is kind of like promising that nuclear waste will always be cared for. No government or agency has ever survived indefinitely, or for that matter always had wise people in charge of sufficient funding to do what is needed, even if they did earlier. There should be guidelines in place for what to do with collections and especially types, so they are reassigned to other institutions if an herbarium or other taxonomic collection is reduced in size or closed, so it is not left to a director or board of trustees of the moment to make decisions without reputable guidelines, especially for those taxa they may not know much about. These guidelines could be part of museum studies training, and sent to all known managers of collections, museum directors, etc. Still, this will continue to put additional burdens on major institutions. They have already had to absorb smaller collections repeatedly. They may not be able or willing to absorb non-type material. It would also be best if isotypes, paratypes, etc. did not end up in the same place as their holotypes, except perhaps when taxonomic revisions are in progress.