Among the papers left by the late Dr. Van Steenis the following manuscript was found, nearly finished. It seemed of sufficient interest to botanists on holiday who can’t leave the local flora alone. Just because one’s mind is elsewhere during holidays beaches are undercollected areas and interesting finds may be expected. It must be understood that this is a key to the common species in natural formations on sandy or rocky substrates, e.g. of the sandy beach, the beach forest, the pes-caprae- and Barringtonia-formations, but not of the seagrass- and mangrove-formations. There are many species that have only a limited distribution, or occur only sporadically, or, especially in tourist-infested areas, are actually inland weeds. These have not been included as a key to them all was beyond the idea of this note. At the end a list of some rarely, or facultatively natural occurring species is given by family. Any species seen that has not been enumerated here is not necessarily an addition on a rare one, yet, one never knows, of course, and it would be prudent to collect some of it for a second look back home, where it may serve at least as a souvenir of a good time.