Senegalia greggii, formerly known as Acacia greggii, is a species of tree in the genus Senegalia native to the southwestern United States and northern Mexico, from the extreme south of Utah south through southern Nevada, southeast California, Arizona, New Mexico and western Texas to Baja California, Sinaloa and Nuevo León in Mexico. The population in Utah at 37°10' N is the northernmost naturally occurring Senegalia species anywhere in the world. Common names include acacia bush, catclaw acacia, catclaw mesquite, Gregg's catclaw, paradise flower, wait-a-minute bush, and wait-a-bit tree; these names mostly come from the fact that the tree has numerous hooked prickles with the shape and size of a cat's claw which tend to hook onto passers-by; the hooked person must stop ("wait a minute") to remove the prickles carefully to avoid injury or shredded clothing. (The common name "cat's claw" is also used to refer to several other plant species, including Uncaria tomentosa, a woody vine found in the tropical jungles of South and Central America.) The specific epithet greggii refers to Josiah Gregg, a 19th-century author, explorer, and amateur naturalist of the American Southwest and northern Mexico. Description It is a large shrub or small tree growing to tall with a trunk up to diameter. The grey-green leaves are deciduous, and bipinnate, divided into 1-3 pairs of pinnae, each pinna long with 10-18 leaflets that are . Pinnae are most frequently in two pairs, with the proximal pair perpendicular to the petiolule and the distal pair forming a V at the tip. The blooms are produced in dense cylindrical spikes of numerous flowers, each individual flower with five cream colored petals and numerous creamy yellow stamens. The fruit is a flat, twisted legume (pod) long, containing generally 3 to 5 hard, flattened, medium brown seeds. The seed pod is constricted between seeds (a loment), and seed dispersal occurs both through dehiscence and breaks at these constrictions. Ecology Senegalia greggii is most common in arroyos where its roots have access to deep water. Its seeds require physical scarification in order to germinate. This effectively prevents germination unless a flash flood disturbs the area and deposits enough water to increase the likelihood that seedlings will be able to establish deep enough roots to survive the dry season. Catclaw is fully drought deciduous and will usually lack leaves for most of the year. S. greggii has extrafloral nectaries, a trait shared