Ponderosas and Jeffrey Pines are tricky to tell apart, since they share similar puzzle-piece-style bark. Here's one no-fail indicator, though: if you take a big whiff of said bark and it smells like butterscotch, you're inhaling Jeffrey Pine.
Before you reach this particular tree, you'll pass three or four other big ones beside the trail that fail the smell test, either because they're not Jeffrey Pines or because they're dead. You can safely pass them by, although it wouldn't hurt to smell them too for control purposes, and it's a useful test of native panache to see how much of your dignity you can maintain while you're shoving your nose into a tree trunk.
Whatever your level of scientific rigor on the early trees, though, don't skip this one; it's got a strong, unmistakable aroma, and if you're currently doubting the veracity of this web page or possibly the sobriety of its author, you'll want to write a heartfelt apology after you've sampled the bouquet of a Jeffrey Pine at its peak.
The tree is about two-thirds of a mile from the trailhead; it might help to watch for the fallen log in the foreground. Remember: if you don't snuff up these wonderful smell molecules, someone else will get them instead.
The big lump of granite in the back left of the photo is, as you've probably already figured out, Sentinel Dome. The trail ascends it on the far side.