Seven things to know about the 78th Masters:

1. A Masters without Tiger

Tiger Woods, a four-time Masters champion, had back surgery to relieve a pinched nerve 10 days before the opening round. He will not play the Masters for the first time since 1994, when he was a senior in high school.

2. Ode to Eisenhower Tree

    Most Read Stories

The most famous tree at Augusta National is no more. The Eisenhower Tree, a 65-foot loblolly pine that was about 210 yards off the tee on No. 17, could not be saved from extensive damage caused by an ice storm in February. It was named after former President Dwight D. Eisenhower, an Augusta member who hit into it so often he proposed chopping it down during a club meeting in 1956. Eisenhower, running for re-election, was overruled.

3. The rookies

At 23, the number of first-timers at the Masters is the most since 1935, and this is believed to be the strongest rookie class ever. Ten of 17 professionals are in the top 50 in the world ranking, led by 20-year-old Jordan Spieth at No. 13.

4. Unpredictable Phil

Phil Mickelson had a runner-up finish in Abu Dhabi to start his season, and he hasn’t cracked the top 15 in any tournament since. He has withdrawn twice because of soreness in his back. A victory would tie him with Woods and Arnold Palmer with four green jackets.

5. House rules

The Masters will be under greater scrutiny than usual over the rules after what happened with Woods last year, when he was penalized two shots for taking an improper drop. Even though he had already signed his card, he was allowed to play because of what Augusta National called a committee error.

6. Father and son

Kevin Stadler won the Phoenix Open, so he will join his father, Craig Stadler, the 1982 champ, as the only father and son to play in the same Masters.

7. Irish eyes are smiling?

This could be good news for Northern Ireland’s Graeme McDowell, Rory McIlroy and Darren Clarke. The other four majors Woods didn’t play because of injury were won by Padraig Harrington of Ireland (2008 British Open and ’08 PGA), McIlroy (2011 U.S. Open) and Clarke (2011 British Open).