Question: If Serissa is a genus of a flowering plant, what is Westringia a genus of?
Context: Chrysanthemum japonense (also known as "ashizuri noji-giku Ashizuri" (Japanese) meaning ""Point wild roadside daisy"" or gold / silver chrysanthemum in English) is a flowering plant within the Asteraceae family and "Chrysanthemum" genus and has a 27 pairs of chromosomes.  It is a perennial flowering plant with leaves between 3–5 cm in length and flower heads that are 3-4.5 cm with white petals.  Typically, flowering occurs in October to December annually.  It the floral emblem of Hyōgo Prefecture. Chrysanthemum boreale (or "Dendranthema boreale") is a flowering plant within the Asteraceae family and "Chrysanthemum" genus.  It used to be in the compositae family and many books still contain as such.  It is a perennial flowering plant that is often noted because of its yellow flowers.  It has 18 chromosomes at the diploid stage. Arenaria bryophylla is a flowering plant in the sandwort ("Arenaria") genus.  It occurs in the Himalaya of China, Tibet, Nepal, Sikkim, and India.  It is the highest known flowering plant, occurring as high as 6180 m . Nolina nelsonii (Blue Nolina or Nelson's Bear Grass), often misspelled "Nolina nelsoni", is a flowering plant in the genus Nolina.  The species was first described in 1906; in its genus, it is morphologically most similar to Nolina parryi.  This extremely drought-tolerant plant is native to the deserts and montane regions in the State of Tamaulipas in northern/northeastern Mexico.  It is known to be cold-hardy to at least -12 °C.  It develops a trunk mesuring from one to several meters high, making it an arborescent member of its genus.  The bluish-green leaves, with finely toothed margins, are borne in dense rosettes, each with up to several hundred stiff linear (narrow) leaves up to 70 centimeters long.  It is dioecious; upon reaching sexual maturity, its white-flowered inflorescence appears in Spring.  The fruit capsules are around 80 mm in length, containing light-brown, spherical to oblong seeds 2–3 mm in diameter.  After blooming, the plant's main trunk dies and multiple lateral trunks emerge to take its place. Sarcodes is a monotypic genus of a north-west American, springtime, flowering plant in the heath family (Ericaceae), containing the single species Sarcodes sanguinea, commonly called the snow plant or snow flower.  It is a parasitic plant that derives sustenance and nutrients from mycorrhizal fungi that attach to roots of trees.  Lacking chlorophyll, it is unable to photosynthesize.  Ectomycorrhizal (EM) symbioses involve a mutualism between a plant root and a fungus; the plant provides fixed carbon to the fungus and in return, the fungus provides mineral nutrients, water and protection from pathogens to the plant.  The snow plant takes advantage of this mutualism by tapping into the network and stealing sugars from the photosynthetic partner by way of the fungus.  This form of parasitism is known as mycoheterotrophy. Ravenala is a genus of flowering plants with a single species, Ravenala madagascariensis, commonly known as traveller's tree or traveller's palm, from Madagascar.  It is not a true palm (family Arecaceae) but a member of a monocotyledonous flowering plant family, Strelitziaceae.  The genus is closely related to the southern African genus "Strelitzia" and the South American genus "Phenakospermum".  Some older classifications include these genera in the banana family (Musaceae).  Although it is usually considered to be a single species, four different forms have been distinguished. Serissa is a genus of flowering plants in the family Rubiaceae, containing only one species, Serissa japonica.  It is native to open sub-tropical woodlands and wet meadows in southeast Asia, from India, and China to Japan.  It is commonly called the snowrose, tree of a thousand stars, or Japanese boxthorn; and was formerly called Serissa foetida.  'Foetida' referres to the unpleasant, vomit-like, odour that the trees give off if their leaves are pruned or bruised. Westringia is a genus of Australian shrubs.  As with other members of the mint family their upper petal (or lip) is divided into two lobes.  There are four stamens - the upper two are fertile while the lower two are reduced to staminodes.  The leaves are in whorls of 3 or 4. Disporum viridescens is a species of flowering plant in the genus "Disporum".  Like other species in the genus, it grows from a rhizome.  The plant is 30 to 80 cm tall, with a stem that may branch.  The leaves are more-or-less ovate in shape with a very short petiole (stalk).  One or two open flowers are borne at the ends of stems; they have greenish white tepals which are 1.5 to 2 cm long.  Flowering is in late spring to early summer (May to June in the northern hemisphere).  Black berries around 1 cm in diameter appear a few months later. Westringia eremicola, commonly known as slender westringia or slender western rosemary, is a flowering plant species that is endemic to south-eastern Australia
Answer: Westringia is a genus of Australian shrubs.