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Reproduction of Crassula helmsii by seed in western Europe

The amphibious plant species Crassula helmsii is a widely established and still-spreading alien in various parts of Europe, where it is considered invasive as its dense swards stress the viability of local biota. The species was considered to exclusively reproduce through vegetative means, until
ex situ germination was recorded from a single locality in Belgium. We assessed whether this seed viability holds on a wider scale, by testing 16 populations from The Netherlands, Belgium, northern France, eastern England and northern Germany in a greenhouse germination experiment. Seedlings were observed from all populations but two, and from each of the five countries. Although most fruits were lacking seeds and the inferred germination percentages were overall low, germinable seed numbers are considerable given the high density of flowering stems. An in situ test revealed seeds to make it through normal winter conditions without signs of physical damage and with retention of germinability. Our results suggest that reproduction by seed is a relatively cryptic but widespread phenomenon throughout western Europe. The persistency of seed banks requires further investigation. Nonetheless, these findings already challenge the efficacy of techniques currently applied in C. helmsii control.

Details

Volume 11
Tijdschrift nummer 2
Pagina's (van-tot) 125–130
Type A1: Web of Science-artikel
Categorie Onderzoek
Tijdschrift Aquatic Invasions|Aquatic Invasions Published online:
Issns 1818-5487
Uitgeverij International Association of Theoretical and Applied Limnology (SIL)
Taal Engels
Bibtex

@misc{76e8b0b0-d461-4ae4-9874-f62cb1728fb5,
title = "Reproduction of Crassula helmsii by seed in western Europe",
abstract = "The amphibious plant species Crassula helmsii is a widely established and still-spreading alien in various parts of Europe, where it is considered invasive as its dense swards stress the viability of local biota. The species was considered to exclusively reproduce through vegetative means, until
ex situ germination was recorded from a single locality in Belgium. We assessed whether this seed viability holds on a wider scale, by testing 16 populations from The Netherlands, Belgium, northern France, eastern England and northern Germany in a greenhouse germination experiment. Seedlings were observed from all populations but two, and from each of the five countries. Although most fruits were lacking seeds and the inferred germination percentages were overall low, germinable seed numbers are considerable given the high density of flowering stems. An in situ test revealed seeds to make it through normal winter conditions without signs of physical damage and with retention of germinability. Our results suggest that reproduction by seed is a relatively cryptic but widespread phenomenon throughout western Europe. The persistency of seed banks requires further investigation. Nonetheless, these findings already challenge the efficacy of techniques currently applied in C. helmsii control. ",
author = "Bram D'hondt and Luc Denys and Wim Jambon and Roeland De Wilde and Tim Adriaens and Jo Packet and Johan van Valkenburg",
year = "2016",
month = jan,
day = "01",
doi = "https://doi.org/10.3391/ai.2016.11.2.02",
language = "Nederlands",
publisher = "International Association of Theoretical and Applied Limnology (SIL)",
address = "België,
type = "Other"
}

Auteurs

Bram D'hondt
Luc Denys
Wim Jambon
Roeland De Wilde
Tim Adriaens
Jo Packet
Johan van Valkenburg