R. arborescens and R. prunifolium are some of the latest blooming ones. Rebloomers like the Encore Azaleas could also be reblooming around now.

Most likely species in MA with large evergreen leaves is r. maximum or one of the maximum hybrids such as Maxecat.A good way to tell is that the blossoms are usually partly obscured by the current year's leaves. This is a species native to all the northeastern states - a small native stand even in southwestern ME. R. maximum is a July bloomer, probably even later than usual this year because of the unusually cool, wet conditions.

Agree with mainegrower in that the most likely candidate for a elip (large leafed rhody) IS probably r. maximum. I have the species currently blooming (via seed from Mt. Mitchell in NC) which I picked up a couple of years ago from RareFinds' Dog Sale (and which is currently flowering for the first time this year).

There are more than a few leps now blooming in the garden as I have r.prunifolium, r. arborescens, r. 'Lady Barbara', r. Weston's Lemon Drop and r. millenium currently aflower.

That's nice. Have you taken a picture of the Rarefinds Purchase in bloom that you can share? Or the other ones?

R. maximum blooms late (late June to early July) with small flowers that are more star shaped than most rhododendron flowers.

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Rarefind's Rhododendron maximum (species)

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Rarefind's Maximum Roseum (hybrid)

Here is a link that might be useful: Rarefind Nursery in Jackson, NJ.

I do have Luis. I'll post something in the next couple of days as I've always been 'challenged' relative to getting photos 'up' on this site.