Serapias cordigera. An orchid. The orchidaceae has got to be the most numerously represented family of plants on stamps, genus wise. This genus has been shown four time on stamps. 2003.
Isoplexis sceptrum of Madeira. The only time a specie of this genus is shown on a stamp. And nicely made too. 1981.
Tolpis azorica. This is the only time this genus has been on a stamp. Rare indeed. 1981.
Laurus azorica. This is actually an addition. I've already posted a stamp of Yougoslavia from 1967 showing Laurus nobilis but the first letter of the genus in in lowercase. This stamp of Açores has it in uppercase as genus names should be. BTW, this is the only showing of L. azorica on a stamp while L. nobilis has been shown numerous times. 1981.
Lactuca watsoniana. Lactuca is the genus of the lettuce. Yes, this vegie has been in everybody's mouth at one time or another (almost daily for many), yet this is the first time it's genus name has been mentioned on a stamp, and that from a rare wild rather than the widely cultivated specie. So goes the representatons of plants on stamps. 1982.