Invasive Species Compendium

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Abstract

Spontaneous synanthropic xenophyite flora in the Canary Botanical Garden Viera and Clavijo.

Abstract

The spontaneous xenoflora annotated in the Canary Botanical Garden Viera y Clavijo in 107 inventories consists of 168 taxa (69 families, 133 genera), representing 24% of the allochthonous flora in the Canary Islands, 26.4% of the estimated xenoflora for the island of Gran Canaria, 39.3% of the spontaneous flora that grows in the Botanical Garden and 7.3% of the total living plants (cultivated or spontaneous), which grows in the Canarian Botanical Garden. The high percentage with respect to the xenoflora of the Canary Islands and Gran Canaria (around 25%), is explained by the generally ubiquitous character of the species. The value of about 40% of all spontaneous flora within the Botanical Garden, compared to 60% of the endemic or native spontaneous flora, reflects the clear dominance of the latter component, which is even higher when compared to the total living plants within the premises, where the spontaneous xenoflora component barely fares 7% of the total. Following adaptation criteria, we record 27 taxa (16%), as probable introduced species, 107 (64%), as sure introduced and 34 (20%), listed as invasives. However, the distribution of species by inventories is very disparate, with a majority of rather poorly represented species, 107 species (63.7%) appear in three inventories at most, while a single species, Oxalis pes-caprae, is in more than 40 inventories, and only 8 are in more than 20: Achyranthes sícula, Bidens pilosa, Conyza bonariensis, Conyza canadensis, Dichondra micrantha, Opuntia maxima, Oxalis pes-caprae and Pelargonium inquinans, most adventitious and ruderal weeds. The constant monitoring and control carried out on the xenoflora within the premises of the Canarian Botanical Garden makes its total numbers of it variable, its presence often ephemeral, and in general un problematic, even considering that the "rain" of propagules from the environment is permanent. In any case, it is advisable to monitor the arrival and expansion of certain invasively trended species such as Anredera cordifolia, Asparagus aethiopicus, Crassula lycopodioides, Crassula ovata, Passiflora morifolia, Passiflora suberosa, Pittosporum undulatum and Schinus terebinthifolius or even Tetraclinis articulata or Washingtonia robusta.