Hoya pubicalyx „Red Buttons“

Beschreibung

Nachfolgenden finden Sie eine Beschreibung der Unterschiede zwischen den sehr ähnlichen Hoya pubicalyx „Red Buttons“ und Hoya pubicalyx „Royal Hawaian Purple“ (Quelle: https://www.houzz.com/discussions/1952993/royal-hawaiian-purple-or-red-buttons; 22.07.2020).

1). Royal Hawaiian Purple is the correct name for the one you have seen labeled Hoya chimera and Hoya pubicalyx cv. Chimera. Back in the early 1980s, Dexter Heuschkel sent cuttings of this to both Dale Kloppenburg and to me. Dale who was anxious to get his name attached to as many new species as possible, wrote it up as a new variety of Hoya pubicalyx, which he called Hoya pubicalyx chimera (I think he spelled that a bit differently). Dexter included collection data with those cuttings and I checked it out. The collection data was the address of a flower shop in Manila. He did not get it from the jungle. The owner of the flower shop was a customer of mine. I sold that hoya to her around 1977. It was Royal Hawaiian Purple.
2). Red Buttons is the name of a cultivar of the late Genevieve McDonald of Merritt’s Island, FL. I have a letter in my files from Mrs. McDonald saying that she selected it from seedlings found on a hoya growing in her garden. It differs from Royal Hawaiian Purple in having smaller leaves with less speckling on them Contrary to what you may have read elsewhere, there is some speckling on some of the leaves but not all. Contrary to what you may have read elsewhere, the flower of Red Buttons DO sometimes appear variegated as do those of Royal Hawaiian Purple.
The dark red (almost black) coronas are an illusion. I have done countless experiments with these flowers and I learned that the corona is transparent and the corollas more or less white. The corona is filled with a sponge-like material as is an area surrounding the carpels. There are nectaries at the base of the carpels which exude dark red, almost black nectar. This blachish red nectar is absorbe by the „sponge“ and drawn up into the corona, making the lobes appear dark. In cool weather this absorption is very gradual so that the sap fills the corona lobes and leaks out from between the anther wings and colours the corolla evenly, before the buts open.
In very hot weather this dark sap „boils“ over and starts spilling out before the flowers open and the result it that much of it spills without touching all parts of the corolla petals and you have a variegated flower. My observation is that this is less likely to occur when plants are growing outdoors. Plants receiving direct sun through glass are more likely to have this happen as glass multiplies the the amount of heat generated by the sun.
My conclusion is that the flower colour comes from that sap and variegation from overheating of that sap.