About Alternanthera echinocephala (Hook.fil.) Christoph.
Alternanthera echinocephala is a heavily branched shrub that can grow up to 2 meters (7 feet) tall. Its leaves are arranged oppositely along the stems, and are narrow, pointed (lanceolate) with smooth, untoothed margins, measuring 7–9 cm (2.8–3.5 in) long. The species' flowers are clustered into somewhat rounded spike-shaped clusters called heads, which are about 10–15 mm (0.4–0.6 in) across. Each individual flower has one large and two small bracts positioned below it, and these bracts make up the most visible part of the flower head. The bracts are greenish-white, and sometimes have pinkish undertones. The small sepals are a similar color to the bracts, and are only 5–10 mm (0.2–0.4 in) long. The flowers have no petals, and have five stamens. Thirteen species in the genus Alternanthera are found in the Galápagos Islands, and six of these are endemic to the area. A. echinocephala is described as easy to distinguish from other Alternanthera species in the region due to its relatively large, spiny-appearing flower heads. As of June 2015, the Tropicos database records this species as distributed in the Galápagos Islands and along the coast of mainland Ecuador. McMullen (1999) notes that the species is also known to occur in Peru. Within the Galápagos Islands, it has been recorded from the islands of Española, Floreana, Isabela, Pinta, Pinzón, San Cristóbal, Santa Fe and Santiago, as well as from some smaller islets adjacent to these islands. It grows in the arid lowland regions of the Galápagos.
