In this thread: Appreciation: - Two Rhododendrons with a coloured calyx, I posted a rhododendron with red flowers with a red calyx, and called it 'May Day', because the photo in the Park Board's https://vancouver.ca/files/cov/ted-and-mary-greig-garden-50-rhododendrons-of-interest.pdf document was too small to see the calyx but it otherwise fit the description: ‘May Day’ is another heavy bloomer. For most of the month of May, true to its name, ‘May Day’ will be a curtain of red, its tubular-campanulate flowers drooping in dense fan-like trusses. This plant also features attractive matte green leaves that have thick, fuzzy, cinnamon brown indumentum on their undersides. ‘May Day’ has a rather dishevelled habit, and will grow wider than it will tall. Also, I saw photos of 'May Day' with a colour calyx, like this photo from Savill Garden, Windsor Great Park, England: File:Rhododendron 'May Day Good Form' - Savill Garden - Windsor Great Park, England - DSC06418.jpg - Wikimedia Commons But then I see in the National Gardening Association Rhododendrons Database this photo with no coloured calyx: Plant database entry for Rhododendron 'May Day' with one image and 12 data details. Wouldn't 'May Day' either have coloured calyces or not? Can that really be variable to a cultivar? And what about this plant in Stanley Park?