A cryptic invader of the genus Persicaria has recently increased in the damper, northern parts of La Palma and Gran Canaria in the Canary Islands (Spain) and locally behaves as an invasive species. Examination of historical herbarium specimens showed this species to be present in Gran Canaria since the 1960s and the same probably applies to La Palma. Up to now, this species had been assigned to the Old World weed P. maculosa. However, morphologically, these plants clearly correspond with P. hydropiperoides, a common and widespread weed native to the New World, and indeed morphologically similar to P. maculosa. Diagnostic features for these two species, as well as for another similar species (P. decipiens, originally described from the Canary Islands), are compared, thoroughly discussed, and copiously illustrated. The current distribution, ecology, and naturalization status of P. hydropiperoides in the Canary Islands are also assessed. The variability of P. hydropiperoides is discussed, more precisely the taxonomic position of a southern ‘race’ of it that is sometimes referred to as a distinct species, P. persicarioides, and to which the Canarian plants belong. The taxonomic value of the latter appears to be clear, although at a lower level. A new combination, at varietal rank, is proposed and validated. In addition to our morphology-based study, a molecular phylogenetic analysis has been conducted on the nuclear ITS region and the plastid DNA region trnL-F.

Otto, R., Scholz, H. & Scholz, S.: Supplements to the flora of the Canary Islands, Spain:Poaceae. - Willdenowia 38: 491-496. - ISSN 0511-9616; © 2008 BGBM Berlin-Dahlem. doi:10.3372/wi.38.38209 (available via http://dx.doi.org/) First records of taxa of Poaceae from the Canary Islands are listed: 11 species and subspecies from La Palma, 4 from Fuerteventura and 2 each from Fuerteventura + La Palma and La Palma + Tenerife. Included in the list are also first records of some species and subspecies from the individual islands of La Palma, Fuerteventura and Tenerife.Polypogonviridis subsp.pauciflorus is described as a sub- species new to science and the new combination Agrostis stolonifera subsp. filifolia is validated.

Varios meses de trabajos de campo en La Palma (Islas Canarias occidentales) han posibilitado el descubrimiento de nuevas plantas vasculares no nativas. Alstroemeria aurea, A. ligtu, Anacyclus radiatus subsp. Radiatus, Chenopodium album subsp. borbasii, Cotyledon orbiculata, Cucurbita ficifolia, Cynodon nlemfuensis, Datura stramonium subsp. tatula, Digitaria ciliaris var. rhachiseta, D. ischaemum, Diplotaxis tenuifolia, Egeria densa, Eugenia uniflora, Galinsoga quadriradiata, Glebionis segetum, Kalanchoe laetivirens, Lemna minuta, Ligustrum lucidum, Lotus broussonetii, Oenothera fallax, Paspalum notatum, Passiflora caerulea, P. manicata × tarminiana, P. tarminiana, Pelargonium capitatum, Phaseolus lunatus, Portulaca trituberculata, Pyracantha angustifolia, Sedum mexicanum, Trifolium lappaceum, Urochloa mutica, U. subquadripara y Volutaria tubuliflora son xenófitos naturalizados o (potencialmente) invasores o de especial interés florístico, que se citan por primera vez para las Islas Canarias o para la isla de La Palma. Tres táxones adicionales, probablemente casuales, se dan a conocer por primera vez de las Islas Canarias, y siete táxones de la isla de La Palma.

Varios meses de trabajos de campo en La Palma (Islas Canarias occidentales) han posibilitado el descubrimiento de nuevas plantas vasculares no nativas. Abutilon theophrasti, Agrostis ^xfouilladeana, Alternanthera brasiliana, Bupleurum salicifolium subsp. salicifolium, Callisia fragrans, Emilia coccinea, Hyparrhenia sinaica, Ipomoea purpurea, Jasminum polyanthum, Macfadyena unguis-cati, Malvastrum coromandelianum subsp. coromandelianum, Misopates calycinum, Nephrolepis cordifolia, Opuntia microdasys, Passiflora subpeltata, Plantago lanceolata, Polygonum aviculare subsp. rurivagum, Pseudogynoxys chenopodioides, Psidium littorale, Robinia pseudoacacia, Rosa micrantha, Rumex bucephalophorus subsp. gallicus, Sorghum bicolor subsp. verticilliflorum, Sphagneticola trilobata, Syzygium jambos, Thunbergia alata y Youngia japonica subsp. japonica son xenófitos naturalizados o (potencialmente) invasores, se citan por primera vez para las Islas Canarias o para La Palma. Se dan a conocer por primera vez 14 t·axones adicionales, probablemente casuales, de las Islas Canarias y 15 taxones de la isla de La Palma.

Durchflusszytometrische Ploidiebestimmungen von untersuchten Senecio-Arten lassen auf Tetraploidie schließen. S. aquaticus aus dem Alpenvorland wies geringere relative DNA-Gehalte als Pflanzen aus anderen Gebieten auf. Messungen von Scrophularia umbrosa s. l. bestätigen und ergänzen die bisher bekannte Verbreitung von S. neesii und S. umbrosa s. str. in Deutschland. Messungen von Aira ergaben keinen Hinweis auf ein Vorkommen von A. multiculmis an den untersuchten Standorten.

A cryptic invader of the genus Persicaria is recently increasing in the damper, northern parts of La Palma and Gran Canaria in the Canary Islands (Spain) and locally behaves as an invasive species. Examination of historical herbarium specimens showed this species to be present in Gran Canaria since the 1960’s and the same probably applies to La Palma. Up to now, this species had been assigned to the Old World weed P. maculosa. However, morphologically these plants clearly correspond with P. hydropiperoides, a common and widespread weed native to the New World, and morphologically similar indeed to P. maculosa. Diagnostic features for these two species, as well as for another similar species (P. decipiens, originally described from the Canary Islands), are compared, thoroughly discussed and copiously illustrated. The current distribution, ecology and naturalization status of P. hydropiperoides in the Canary Islands are also assessed. The variability of P. hydropiperoides is discussed, more precisely the taxonomic position of a southern ‘race’ of it that is sometimes referred to as a distinct species, P. persicarioides. In addition to our morphology-based study, a molecular phylogenetic analysis has been conducted on the nuclear ITS region and the plastid DNA region trnL-F.