It is everywhere around here, green amaranth, amaranthus viridis.
It is a declared environmental weed in some places and a prized food in others, see what wikipedia has to say:
Amaranthus viridis is eaten traditionally as a vegetable in South India, especially in Kerala, where it is known as “Kuppacheera”.
In Greece it is called vlita and is one of the varieties of “horta” or greens known in Greek cuisine which are boiled and served with olive oil and lemon.
It is also eaten as a vegetable in parts of Africa. A traditional food plant in Africa, this little-known vegetable has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare.
In Jamaica it is eaten as a vegetable and is known locally as callaloo (not to be confused with callaloo of most other countries).
Amaranthus viridis is used as a medicinal herb in traditional Ayurvedic medicine, under the Sanskrit name Tanduliya.
also known as:
English: Slender Amaranth, Green Amaranth, Pakai
Español: Amaranto Verde, Bledo Verde, Bleo, Moco Pavo
Fiji Hindi: Choraiya
Français: Amarante Verte
lea faka-Tonga: tupu?a, longolongo?uha
It is one of the subjects for the current project you’re involved in, Wild Stories, which looks at the traditional knowledge inhabiting our surroundings in the form of plants >>
Map from Australia Virtual Herbarium