The frontiers on the long strip of land marked out in light green along the Mediterranean Sea on the map behind the midday weatherman on Catalonia's TV3 public broadcaster have little to with the borders of the region that votes for its parliament on Sunday.

Modern Catalonia stops at the coast and the borders of Aragón, Valencia and France – as a separate map also used on the Temps Migdia programme shows.

But this second map describes a far bigger area known as the Catalan Lands, a sort of Greater Catalonia that stretches 200 miles south to Alicante, north beyond the French city of Perpignan and across the seas to Mallorca and the other Balearic Islands. Daily maximum and minimum temperatures are given for places such as Ibiza or Fraga in Aragón.

"These are areas where Catalan is spoken," explained Muriel Casals, president of Òmnium Cultural, a foundation whose mission is to teach and protect the Catalan language – but which is now also threatening to help lead a tax rebellion against the Spanish exchequer. "We see any attempts to attack the language in those places as a threat, because it shrinks the language's boundaries."

Some, such as Isabel-Clara Simó, a Valencia-born writer and candidate for Barcelona with the Catalan Solidarity separatist party, are hoping separatist spirit spreads "by contagion" to the outlying region.

"That looks a bit premature," said Alfred Bosch, a parliamentary deputy for the separatist Catalan Republican Left party. "If they want to join then, of course, they would have all the assistance they want from our party. But it depends on them."

And Artur Mas, president of Catalonia, told the Guardian: "We are not going to make territorial demands. With the rest [of Spain] we can have good neighbourly relations. We can do things together like defend a common cultural and linguistic space or a common economic area. But it is one thing to do that and another to have territorial ambitions. We don't have them at all."

Simó's wait for contagion may prove eternal. "There are some cultural affinities, but there is little support for the idea here," said Ximo Puig, leader of Valencia's socialists. "In fact there are even anti-Catalanists in Valencia and the right uses that to win votes."

Indeed, conservative politicians in the region that lies south of Catalonia have sometimes tried to argue that Valencian and Catalan are not even the same language. "That is ridiculous," said Simó.

In the Balearic Islands, where some view Barcelona with the same degree of suspicion that Madrid provokes in many Catalans, a regional government led by Spanish prime minister Mariano Rajoy's People's party has just stopped funding to the Ramon Llull foundation, which promotes Catalan culture abroad – and is named after a 13th-century Mallorcan writer.

"The Balearic Islands will never form part of the so-called Catalan Lands as long as I am president," said the regional leader, José Ramón Bauzá, in a newspaper interview. "Baleares is part of Spain and we are delighted with that."