Portland-based Umpqua Holdings Corp., parent company of Umpqua Bank, announced Wednesday it is purchasing Western Sierra Bancorp in California in a deal valued at $355 million.

The purchase, expected to be completed in the second quarter of this year, will add Western Sierra’s 31 bank branches in Northern California to Umpqua’s 95 branches in three states.

All Western Sierra subsidiaries, including Western Sierra Bank and Central California Bank branches, will switch to the Umpqua Bank brand.

Under the purchase agreement, Western Sierra shareholders will receive 1.61 shares of Umpqua’s stock for every Western Sierra share they hold. Umpqua officials say the company expects to issue 12.5 million shares of its stock.

The combined company will have $6.9 billion in assets.

”Western Sierra’s significant presence in the greater Sacramento area and San Joaquin Valley makes it a strong fit,” Umpqua President and CEO Ray Davis said in a written statement.

Umpqua Bank, based in Roseburg, has branches in Oregon, Washington and California. It operates two branches in Bend.

Umpqua’s shares closed at $26.59 Wednesday, down 67 cents, or about 2.5 percent, after the announcement.