Question: Which is a genus of vine, Epithelantha or Hardenbergia?
Context: Tutin is a poisonous plant derivative found in the New Zealand tutu plant (Coriaria arborea, "Coriaria" genus, several different species).  It acts as a potent antagonist of the glycine receptor, and has powerful convulsant effects.  It is used in scientific research into the glycine receptor, and is also sometimes associated with outbreaks of toxic honey poisoning when bees feed honeydew exudate from the sap-sucking insect commonly known as the passion vine hopper, when these vine hoppers (Scolypopa australis) have been feeding on the sap of tutu bushes.  Toxic honey is a rare event and is more likely to occur when comb honey is eaten directly from a hive that has been harvesting honeydew from passion vine hoppers feeding on tutu plants. Cissus hypoglauca is a common Australian vine.  It is one of the better known climbing plants of the genus "Cissus" in the grape family.  A very common climber in moist areas of eastern Australia, it often colonises large areas after forest damage due to storms, fire or logging.  Common names include jungle grape, water vine, giant water vine, five-leaf water vine, jungle vine, native grapes and billangai . Hardenbergia violacea syn.  "H. monophylla" is a species of flowering plant in the pea family Fabaceae, native to Australia from Queensland to Tasmania.  It is known in Australia by the common names false sarsaparilla, purple coral pea, happy wanderer, native lilac and waraburra (which comes from the Kattang language).  Elsewhere it is also called vine lilac or lilac vine. Epithelantha micromeris is a button cactus in the genus "Epithelantha".  It is characterized by its white-grey spines growing on a globular shaped stem.  The density of its white spines give it the illusion of being completely grey, making it very difficult to see the green color beneath.  It grows to be 1-5 cm tall, and roughly 2-4 cm in diameter.  "E. micromeris" produces small, pink-white flowers, often considered to be some of the smallest of the cacti.  These flowers give way to a bright red, cylindrical fruit which contains several black seeds and also is edible. Cynanchum utahense is a species of flowering plant in the "Cynanchum" genus of the dogbane family, known by the common names Utah swallow-wort and Utah vine milkweed.  This relatively uncommon perennial vine is native to the Mojave Desert from California, Nevada, Utah and Arizona in the United States.  This is a small vine with a highly branched, twining stem rarely exceeding a meter in length with which it physically supports itself on other shrubs and trees.  It has small narrow leaves a few centimeters long.  Its flowers are bright yellow to orange and grow in umbels.  The fruit is a grooved follicle several centimeters long. Ceropegia is a genus of plants within the family Apocynaceae, native to Africa, southern Asia, and Australia.  It was named by Carl Linnaeus, who first described this genus in volume 1 of his "Species plantarum", which appeared in 1753.  Linnaeus thought that the flowers looked like a fountain of wax.  From this the scientific name was derived: ‘"keros"’ meaning wax and ‘"pege"’ meaning fountain (Pooley, 1998).  They have many common names including lantern flower, parasol flower, parachute flower, bushman’s pipe, string of hearts, snake creeper, wine-glass vine, rosary vine, and necklace vine. Hardenbergia is a small genus of leguminous vines from Australia. Epithelantha (button cactus) is a genus of cactus that is native to northeastern Mexico, and in an area from western Texas to Arizona.  "Epithelantha" has two species, "Epithelantha micromeris" and "Epithelantha bokei".  The name "Epithelantha" refers to the flower position near the apex of the tubercles. Cochliasanthus caracalla is a leguminous vine from the family Fabaceae, originating in tropical South America and Central America.  The species is named "caracalla", a corruption of the Portuguese caracol, meaning snail.  This perennial vine (when grown in a climate without frost) has fragrant flowers said to be reminiscent of hyacinths - with a distinctive curled shape, giving rise to the common names corkscrew vine, snail vine, snail creeper, snailflower or snail bean.  It is the only member of the genus Cochliasanthus and was formerly considered to belong to the genus "Vigna". Ipomoea quamoclit (cypress vine, cypressvine morning glory, cardinal creeper, cardinal vine, star glory or hummingbird vine) is a species of vine in the genus "Ipomoea" native to tropical regions of the New World and naturalized elsewhere in the tropics.
Answer: Hardenbergia