Fig. 1

Gel electrophoresis of genomic DNA (200 ng DNA/lane) providing a visualization of DNA degradation. Fresh tissue produced high molecular weight DNA with herbarium specimens producing variable range of DNA degradation, from samples that had DNA highly degraded (< 0.7 kb; 3, 5, 7, 8) to less degraded (fragments in 2–8 kb; 4, 6). Genomic DNA from fresh tissue: (1) P. aquatica (PI 476288) and (2). P. arundinacea (PI 241065), both > 10 kb; from herbarium: (3) P. canarensis (619107) and (4) P. brachystachys (ISC-V-0021035); herbarium specimens that were PCR re-amplified (5) P. paradoxa (ISC-V-0021361) and (6) P. coerulescens (ISC-V-0021204). Herbarium specimens with unsuccessful PCR amplifications (7) P. canarensis (71229) and (8) P. minor (229774). ITS region amplification (fresh and herbarium samples) and re-amplification is presented on Fig. 3. M – DNA size marker; CT – no sample loaded. Full-length blots/gels are presented in Supplementary Fig. 1