Hoya kerrii has perfectly heart-shaped bright green leaves that emerge on vining stems. Aptly nicknamed the Sweetheart Hoya or Heart-leaf Hoya, this slow grower is most commonly sold only as a single rooted leaf around Valentine's Day. Like all Hoyas (aka wax plants), clusters of star-shaped flowers will eventually emerge along the stems. Happy to climb up a trellis or cascade over the sides of its pot, Hoya kerrii is one of those must-have plants for any collector.