Not everyone's cup of tea!
In the south or Brazil, and Argentina and neighbouring countries, it is common to see people walking with large "thermos"* vacuum flasks. It seems an odd sight but it's a frequent one even in the shopping areas of large cities like Buenos Aires or small towns such as Gramado or Canela.
What was behind this strange behaviour?
This is gaucho country and gauchos have a habit of drinking erva-mate, or chimarrão, a type of tea traditionally drunk from a calabash gourd though a silver straw. Erva denotes a herbal tea, while mate, or mati, denotes the pot i.e. the gourd in which it is served, though also infers the tea itself.
This drink was adopted by the Spanish and Portuguese colonists who found the indigenous guarani drinking it on a regular basis. Gauchos, the cowboys that roamed the grasslands, would (and still do) ride and sip from their gourds while rounding up cattle. The caffeine in this infusion helps keep the gauchos awake in the saddle.
The tea is made from the leaves of a tree, Ilex paraguariensis, a species of holly endemic to the region. Dried leaves are ground into fine particles and packed into the gourd which has a straw-like tube protruding from it. The end of the tube, traditionally made from silver (a once-plentiful commodity in Argentina), has a sieve at the bottom end that filters out broken stems and larger pieces of the leaf.
The tea, as well as being high in caffeine, is a source of vitamins B and C and is rich in antioxidants.
There seems to be a bit of a science to the preparation of the chimarrão, as most Brazilians refer to it. The erva must be placed in the gourd in a certain way and water added at the right temperature both in the preparation stage and when ready for drinking. The straw can be placed in the gourd either at the time inserting the tea or after. Either way there is a method to ensure tea can be drunk without blocking the filter.
The chimarrão is usually shared, like a pipe of peace, so family groups will carry just one gourd and one flask of hot water. When meeting others it is common to offer a sip of tea from the communal pot.
While generally regarded as a gaucho tradition it is also common to see this in Syria and Lebabon (Brazil has large immigrant populations of Sirio-Lebanese which may have caused the export of the guarani/gaucho habit).
It's an acquired taste, a bit like green tea but with a grassy flavour. Not everyone's cup of tea!!
* Thermos (upper case T) is a registered trade mark of Thermos LLC, a Chicago-based manufacturer of vacuum flasks. thermos (lower case t) is a generic term for vacuum flasks.
Guarani - indigenous group of South America
Calabash - a type of gourd
Erva - Herb
Gaucho - horsemen of South America