Physical distribution of full-length A. thaliana retroelements. The five A. thaliana chromosomes are designated as Ath1-5. Triangles indicate the location of a particular retroelement on the chromosome. Non-LTR retrotransposons are in black, Pseudoviridae in gray, and Metaviridae in white. Vertical bars on the chromosome show the precise location of the retroelement. Regions of heterochromatin are represented as follows: telomeres and NORs (on Ath2 and Ath4) by rounded chromosome ends; centromeres by hourglass shapes; heterochromatic knobs (on Ath4 and Ath5) by narrowed stretches on chromosome bars. The relatively short chromosome 5 knob is barely visible to the right of the centromere. The inset more clearly depicts heterochromatic regions that are obscured by element insertions. Chromosomes are drawn to scale.