That wrought by man in destroying forests and cultivating the land will be no less effective, and already specimens in our herbaria alone represent species no longer to be found in a living state.
There are large herbaria at the British Museum and at the Royal Gardens, Kew, and smaller collections at the botanical institutions at the principal British universities.
Herbaria are also associated with the more important botanic gardens and museums in other countries.
The Berlin herbarium is especially rich in more recent collections, and other national herbaria sufficiently extensive to subserve the requirements of the systematic botanist exist at St Petersburg, Vienna, Leiden, Stockholm, Upsala, Copenhagen and Florence.
Where, as in private herbaria, the specimens are not liable to be handled with great frequency, a stitch here and there round the stem, tied at the back of the sheet, or slips of paper passed over the stem through two slits in the sheet and attached with gum to its back, or simply strips of gummed paper laid across the stem, may be resorted to.