The Green-Rainbow, the state affiliate of the Green Party, Party’s 2006 nominee for governor of Massachusetts has announced that she will be running in the Democratic primary. Grace Ross is challenging incumbent governor Deval Patrick, and will need “15 percent of the delegates at the party’s convention in June to qualify for the primary ballot,” and thousands of additional signatures. If she does qualify for the ballot, she could be the only Democratic opponent of the governor. From the Boston Globe:
As the Green Party candidate in 2006, Ross at times challenged Patrick from the left, particularly in debates. She ended up garnering less than 2 percent of the vote in an election in which Patrick won in a landslide, with 55 percent of the ballots casts in the four-way race.
Ross, 48, of Worcester, said she was running as a Democrat this year to see if the party truly represents everyday people. “Let’s see if the Democratic Party can live up that image, because we need it,’’ Ross said in a telephone interview. “Look at the job loss rates. Look at the homelessness. Look at the increasing hunger. The list is long”…
Ross becomes one of six candidates seeking the corner office this year, joining Republicans Christy Mihos and Charles D. Baker; state Treasurer Timothy P. Cahill, who is running as an independent; and Jill Stein, a Green-Rainbow Party candidate.

You are both correct.
She does need the valid signatures.
However, in order to qualify for the ballot, she needs 15% of the delegates to the Democratic State Convention, and that is not necessarily trivial.
I have no idea. If I’m wrong you can go ahead and correct the article or just let me know what I should change it to.
Doesn’t she also need 10,000 town and state certified signatures from Mass voters who registered as either Democrats or Unenrolled?