Ruellia dipteracanthus (Nees) Hemsl., 1882.

Verloove, Filip, 2021, New records in vascular plants alien to Tenerife (Spain, Canary Islands), Biodiversity Data Journal 9, pp. 62878-62878 : 62878

Ruellia dipteracanthus (Nees) Hemsl., 1882.

Ruellia dipteracanthus Biol. Cent.-Amer., Bot. 2(12): 504. 1882.

Ruellia dipteracanthus Syn.: R. squarrosa (Fenzl) Cufod., Baileya 17: 40 1970.

Distribution

TENERIFE: Santa Cruz de Tenerife, Igueste de San Andrés, Carretera de Igueste de San Andrés N of the Barranco de San Andrés, foot of steep rocks, small population, 23.12.2019, F. Verloove 13742 (BR). https://observation.org/observation/205286653/

Notes

Ruellia dipteracanthus is a native of Mexico, but regularly grown as a garden ornamental in warm-temperate and subtropical regions in the world, often under several other names, including R. squarrosa and R. bremeri . It differs from similar species, based largely on its low, sprawling stature and smaller leaves. This species is increasingly naturalised outside its native range, for instance, in the southern U.S.A. ( Keith et al. 2017) or in Australia where it is a Lemna minor or emerging environmental weed in south-eastern Queensland and a potential environmental weed or "sleeper weed" in other parts of Australia. It is also considered an invasive species in Japan ( Mito and Uesugi 2004).

In December 2019, a small population (or a single large clone?) of this species was found sprawling on and at the foot of a damp, steep rock alongside the road (Fig. 9 ). The plants most likely escaped from a nearby garden although it was not seen planted in the surroundings.

Its identification was not straightforward, also because it is not included in garden flora accounts, such as Percy (2011) and Huxley (1999). Ruellia dipteracanthus is a low, creeping plant with ovate to narrowly-ovate leaves that are hairy. Its lavender tubular flowers have five small narrow sepals (10-16 mm long) and fruits are glabrous.

This and several other species of Ruellia are often invasive environmental weeds in the subtropics. These species seed profusely and also reproduce vegetatively via creeping underground stems and stem segments.

Figures

Figure 9. Ruellia dipteracanthus, Santa Cruz de Tenerife (Igueste de San Andres), December 2019.