Aeschynanthus lobbianus (radicans)
This form of the species A. radicans is usually referred to as A. lobbianus in North America. It is the species to which the common name of "Lipstick Plant" is appropriately applied. The name derives from the appearance of the bright red buds emerging from the dark maroon tubular calyx -- just like a lipstick emerging from its tube. There are other Aeschynanthus (e.g. A. curtisii, A. siphonanthus, A. pulcher) with a similar effect, but the name has come to be commonly applied to all Aeschynanthus, even those that bear little resemblance to this species.
The leaves of A. lobbianus are quite heavy and succulent, and for this species and others with similar foliage, it is important to allow the soil to get fairly dry before watering. Like many Aeschynanthus, A. lobbianus delights in being outside in the summer, in dappled shade or even full sun for part of the morning. The specimen pictured here had been grown by Bill and Sam Richardson, outside under a tree on Cape Cod for most of the summer.
A close-up of the flowers gives a good perspective on the maroon calyces.