It's holly mate
Yerba mate, or simply mate, is a gritty suspension of plant fragments sucked through a hot metal straw called a bombilla. In much of South America, and also parts of the Middle East where it was more recently introduced, you can get your daily caffeine fix from a cup of mate.
The cup was, and sometimes still is, a hollowed out gourd (something from the melon plant family) but these days it can be anything from wood, to glass to plastic.
Typically you share the brew with friends, much like you would a block of chocolate or perhaps a bong. It's not uncommon to see young people in Buenos Aires carrying their mate cup and bombilla in one hand, and a thermos of hot water in the other.
The plant is a local species of holly, Ilex paraguariensis, sometimes but not authentically mixed with other spices and herbs. Originally the plant was collected from the wild by native South Americans, but Jesuits started to culivate Ilex paraguariensis to meet demand and to produce a higher quality product.
The plant has very particular growing requirements, requiring a warm, humid climate and acidic soil. But it can be coaxed into growing outside its comfort zone. The botanic garden in Buenos Aires recently planted a small crop for display and to get healthy and productive trees they excavated a metre or so of soil, replacing it with loam from the plant's natural habitat.
You start with a lot of plant material stuffed into the small cup, adding boiling water. Then suck, swallow and share. After a few slurps you need to add more water and that's when you pass the cup to your mate...
Although confusing in Australia where 'drinking mate' refers to the blokes and sheilas in your shout, it's mate rather than maté according to Encyclopædia Britannica. Maté is Spanish for 'I killed' and the accent is only added by English-speakers to help with pronunciation, and perhaps avoid confusion in the pub.
Plenty of benefits are ascribed to the drink, but also warnings about prolonged use. The Natural History Museum in London describes it as a 'nutritious beverage' and some of the alkaloids stimulate our nervous systems in the same way as coffee and chocolate. The links with cancer are associated with the piping hot bombilla, with which I certainly managed to burn my lips and mouth.
The specially dried leaves (and little twigs) are rehydrated only briefly with hot water for the first dose. It's non-alcoholic but packed full of caffeine and tannins. To me it tastes much like black or green tea, Camellia sinensis (from Asia) but more so.
I enjoyed it about as much as tea and will stick with my Ethiopian plant of choice, Coffea arabica.
Note: All images in my posts from this date (2 June 2015) are enlarged to fit with the new format of the blog (which I switched to 6 July 2015...)