In Brazil, "acelga" is also the popular name of the napa cabbage (Brassica rapa), also known as Chinese cabbage. The chard is not a common vegetable here, so "acelga" usually refers to the that kind of cabbage. Please add this meaning. Reference: Acelga – Wikipédia, a enciclopédia livre
Great! I've added it, complete with the Latin name.
All the dictionaries I have here refer only to "various beets" and particularly the chard (Beta vulgaris). Pretty cool to be able to add a new attested meaning.