Mistletoe the host plant. "Viscum album" successfully parasitizes more than 200 tree and shrub species. All mistletoe species are hemiparasites, because they do perform at least a little photosynthesis for at least a short period of their life cycle. However, in some species its contribution is very nearly zero. For example, some species, such as "Viscum minimum", that parasitize succulents, commonly species of Cactaceae or Euphorbiaceae, grow largely within the host plant, with hardly more than the flower and fruit emerging. Once they have germinated and attached to the circulatory system of the host, their photosynthesis reduces so far that it
What Is and What Should Never Be and What Should Never Be" was performed live at Led Zeppelin concerts between 1969 and 1973. A live version taken from a performance at the Royal Albert Hall in 1970 can be seen on the "Led Zeppelin DVD". Another was included on disc two of the live triple album "How The West Was Won". Two more versions were included in BBC Sessions. What Is and What Should Never Be "What Is and What Should Never Be" is a song by English rock band Led Zeppelin. It was written by Jimmy Page and Robert Plant and was included as the second