Senna artemisioides -- Arizona

These Australian natives have been observed to establish occasionally along roads or in desert areas adjacent to landscapes where they are cultivated. Senna artemisioides subsp. filifolia and Senna artemisioides subsp. petiolaris are widely grown as landscape plants in desert areas of southern and central Arizona (Johnson, 2004). Calflora (2021) lists occurrences in seven counties in the southwestern part of the state. The plant is listed for Cyprus as a a casual escapee (John, Hawkes & Walliker, 2019). It is also documented from Spain's Iberian Peninsula (Laguna, 2010), from the Canary Islands (Verloove, 2017), from Pakistan (Ajaib, et. al, 2011), and from Iraq (Al-Joboury, 2020).

GBIF shows the native range of Senna artemisioides (most of Australia) matches with occurances in the southwest United states and nearby Mexico, and also in southern Africa (GBIF, 2021).

There are multiple reports of naturalization, chiefly in the southwest US (Johnson, 2004), (Calflora, 2021). But these records do not indicate significant economic or environmental damage.

No reports were found showing significant economic or environmental damage caused by introduced Senna artemisioides. However, the plant is regarded as an undesirable rangeland weed in its native Australia (Chimera, 2010).

The online Global Compendium of Weeds lists: Senna alata (Environmental Weed, Noxious Weed); Senna bicapsularis (Environmental Weed, Noxious Weed); Senna didymobotrya (Environmental Weed, Noxious Weed); Senna x floribunda (Environmental Weed); Senna hirsuta (Environmental Weed); Senna multiglandulosa (Environmental Weed); Senna obtusifolia (Environmental Weed, Noxious Weed); Senna occidentalis (Environmental Weed, Noxious Weed); Senna pendula (Environmental Weed, Noxious Weed); Senna septemtrionalis (Environmental Weed); Senna siamea (Environmental Weed); Senna spectabilis (Environmental Weed); Senna sulfurea (Environmental Weed); Senna surattensis (Environmental Weed); and Senna tora (Environmental Weed, Noxious Weed) as a set of naturalizing Senna species around the world which meet the higher impact categories of Environmental Weed or Noxious Weed (GCW, 2007). Of these, Senna hirsuta showed a GBIF match between the southwest US (where it is native) and a part of Australia and southern Africa. Senna occidentalis is native to the US and has a pantropical distribution. Senna didymobotrya is an African species which has naturalized in matching climates in the US and in Australia. These Senna are not as arid-adapted as Senna artemisioides and do not show a clear pattern of being invasive in a similar climate (GBIF, 2016).

Over half the places where Senna artemisioides grows, as mapped by GBIF, match the climate of the area of concern. GBIF does not map all the regions of naturalization indicated in the literature.

Senna artemisioides is rated as not having a climbing or smothering growth habit (Chimera, 2010).

Senna artemisioides is noted as a shrub which can switch between resprouter to non-resprouter life history (following fire) as it progresses from juvenile to adult growth phase (Williams & Bradstock, 2012). Senna artemisioides is rated as creating a fire hazard in its natural habitat (Chimera, 2010).

Senna artemisioides is rated as toxic to livestock. It is considered important weed of rangelands in northern New South Wales (Chimera, 2010).

Senna artemisioides is rated as forming dense thickets. It is considered important weed of rangelands in northern New South Wales (Chimera, 2010). The plant is a large evergreen woody perennial shrub, vigorously upright and billowing to 15 feet with nearly equal spread (Martin, 2021).

Senna artemisioides is rated as not reproducing by vegetative fragmentation (Chimera, 2010). The species has a strong ability to resprout following clipping or burning (Vesk, et al. 2004) but is not reported to spread by root suckers.

Senna artemisioides is rated as not reproducing by vegetative fragmentation (Chimera, 2010).

Senna artemisioides is rated as producing viable seed (Chimera, 2010). Martin (2021) reports the plant readily reseeds in the urban landscape, but also that deliberate propagation from seed is benefited by a hot water soak or acid scarification.

Senna artemisioides is rated as not reaching prolific seed production (Chimera, 2010). However the source material cited in this PIER Assessment is no more than an inference based on the size of the pods.

Senna artemisioides is regarded as having a seed dormancy. This was studied by Pound et. al (2015) as part of a dormancy-breaking survey. It was recommended that seeds of S. artemisioides be pre-treated with wet heat, for restoration programs in its native Australia. Information is not available for the percentage of seeds which germinate in the field without the treatment, so confidence is "Medium."

Senna artemisioides is a woody species, rated as having a 3 year minimum generative time (Chimera, 2010).

Fruit pods are unsightly and should be removed by pruning in late April to early May after flowering (Martin, 2021). This indicates a single short fruiting season in early summer.

Senna artemisioides is rated as not dispersing seeds by way of animals or birds (Chimera, 2010). Noted as unassisted dispersal (no means of external attachment to animals).

Senna artemisioides is rated as not dispersing seeds over a long distance by wind or water (Chimera, 2010).

Senna artemisioides is rated as having propagules dispersed intentionally by people (presumably through the horticulture trade), but not as a seed contaminant, and not unintentionally by human activity. (Chimera, 2010).