Question: Which genus has the most species of trees, Mesquite or Ceanothus
Context: Ceanothus L. is a genus of about 50–60 species of nitrogen-fixing shrubs or small trees in the family Rhamnaceae.  Common names for members of this genus are California lilac, wild lilac, and soap bush. " "Ceonothus"" comes from a Greek word meaning "spiny plant", Ancient Greek: κεάνωθος ("keanōthos"), which was applied by Theophrastus (371–287 BC) to an Old World plant believed to be "Cirsium arvense". Tilia is a genus of about 30 species of trees native throughout most of the temperate Northern Hemisphere.  Commonly called lime trees in the British Isles, they are not related to the lime fruit.  Other names include linden, and basswood for the North American species.  The genus occurs in Europe and eastern North America, but the greatest species diversity is found in Asia.  Under the Cronquist classification system, this genus was placed in the family Tiliaceae, but genetic research summarised by the Angiosperm Phylogeny Group has resulted in the incorporation of this genus, and of most of the previous family, into the Malvaceae. Eidothea zoexylocarya is a species of tall rainforest trees endemic to north-eastern Queensland, Australia and constituting part of the plant family Proteaceae.  In European–Australian science, these trees were only recognised in recent decades, first from the slopes of Mount Bartle Frere, the Queensland mountain which reaches the highest altitude.  In 1995, scientific descriptions of the trees, as this genus and type species, were published for the first time by Andrew W. Douglas and Bernie Hyland.  The species name refers to the almost identical fossil fruit "Xylocaryon lockii" (picture below), from Ballarat, southern Australia, still extant ("zoe" means life) in this north-eastern Australian species. Tibouchina Aubl.  is a Neotropical flowering plant genus in Melastomataceae Juss.  that contains approximately 240 species.  Species of this genus are herbs, shrubs or trees and typically have purple flowers.  They are native to Mexico, the Caribbean, and South America where they are found as far south as northern Argentina.  Members of this genus are known as glory bushes, glory trees or princess flowers.  The name "Tibouchina" is adapted from a Guianan indigenous name for a member of this genus .  A recent systematic study has shown that this genus is paraphyletic. Mesquite is a common name for several small trees in the genus "Prosopis" native to North American deserts. Ceanothus papillosus (wartleaf ceanothus) is a species of plant in the genus "Ceanothus".  It is endemic to California, where it grows in open habitat on the slopes of the coastal mountain ranges, such as woodland and chaparral. The Mezquital Valley (Otomi: B’ot’ähi) is a series of small valleys and flat areas located in Central Mexico, about 60 km north of Mexico City, located in the western part of the state of Hidalgo.  It is part of the central Mexican highlands, with altitudes between 1,700 m and 2,100 m above sea level.  It is one of Mexico's main semi-arid/area regions, whose native vegetation is dominated by cactus species, mesquite trees, and maguey with pine and oak trees in the highest elevations.  It is considered to be part of the northern extension of Mesoamerica, with one major archeological site, Tula, which was the main city of the Toltecs, an important influence for the later Aztecs, this area was on two important Aztec tribute regions, Teotlalpan and Jilotepec Province.  However, from the Aztec period to the 20th century, it was sparsely populated and very poor, with one main indigenous ethnicity, the Otomis.  In the 20th century, irrigation works were created to take advantage of the water in the Tula River, along with wastewater drained from the Valley of Mexico for agriculture.  Today the valley produces various grains and produce, including one-quarter of all green chili peppers grown in Mexico. Cola is a genus of trees native to the tropical rainforests of Africa, classified in the family Malvaceae, subfamily Sterculioideae (or treated in the separate family Sterculiaceae).  Species in this genus are sometimes referred to as Kola tree or Kola nut for the caffeine-containing fruit produced by the trees that is often used as a flavoring ingredient in beverages.  The genus is related to the South American genus "Theobroma", or cocoa.  They are evergreen trees, growing up to 20 m tall (about 60 feet), with glossy ovoid leaves up to 30 cm long and star shaped fruit. Megacyllene antennata is a species of beetle in the family Cerambycidae occurring in the southwestern United States, where its larvae feed on mesquite trees.  It was described by White in 1855. Mesquite is the common name for the genus "Prosopis", containing over 40 species of small leguminous trees.  They are native to the southwestern United States and Mexico (even the creeping mesquite, which is invasive in southern California).
Answer: Ceanothus