Truco is popular in Uruguay, where is is played by different rules from those used in Argentina, though the principles of the game - the Flor, Envido and Truco - are the same. Some time I may expand this page to give a complete description of the Uruguayan game. At present this page only explains the differences from Argentinean Truco.
The main difference is that there is a special suit - "la muestra" (the shown suit) - some of whose cards have enhanced values and powers. After three cards have been dealt to each player, the next card is placed face up on the table, and the remainder of the pack is stacked face down on top of it, crosswise, so that the identity face up card can be seen by all players. The suit of the face up card is the muestra.
The 2, 4, 5, 11 (caballo), 10 (sota) of the muestra suit are special cards - muestras.
followed by the 3's, 2's other than cups, and so on.The 3 and 6 of the muestra suit are ordinary cards like any other 3 or 6, with no special value. The ace and 7 are also ordinary cards - as usual one or both of them are matas if the muestra suit is swords, clubs or coins. The 12 (rey) of the muestra suit has no special value unless the face up card is a 2, 4, 5, 11 or 10. If it is, the 12 takes on the value of the face up card. For example if the 4 of coins is face up, then the 12 (rey) of coins becomes the second highest card in its place, and is a wild card worth 9 in a flor or envido.
Note that if you have a muestra you will always have at least an envido of two cards, using the muestra to match the suit of one of your other cards. You can therefore add 20 to the values of the cards. For example holding the 4 of muestra with a 3 and a 6 of different suits, you have an envido worth 35 (20+9+6), using the muestra with your 6. If you have two cards of the same suit plus a muestra you have a flor. Any hand with two muestras is also automatically a flor.
Note: Uruguayan Truco rules often give the values of the cards of the muestra suit as 30, 29, 28, 27: since a muestra always gives you at least a two-card envido, the 20 points for this are already added into the card value. However, this makes things confusing when you have a hand with two muestras or need to compare a hand with a muestra against one without, so it seems clearer to keep the 20 points separate.
The señas ("signs") in Uruguay are as follows:
Uruguayan Truco can be played by three players. As usual the deal passes to the right after every hand, but the mano (first person to right of dealer) plays alone against the other two players, who play as a team. To even things out a bit, at the beginning of the hand, the mano gets a fourth card dealt to him. Then, after the upcard is revealed, the mano selects one of his cards to discard face down back into the deck. Play then begins with the mano calling either flor, envido or truco or simply playing one of his cards. The play then proceeds as it does normally in the 2 or 4 player versions. Any points scored by either of the two players who are playing together (i.e. the two players other than the mano) are given to both of the players on the team. So, for example, if one of the team members has a flor, the team members get 3 points each. Just as in the 4 player version, the two players who are playing together may give señas ("signs") to each other, but they cannot simply show each other their cards.
At Retruco.com you can play Argentinean or Uruguayan Truco on line.