Senegalia greggii

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 with other senegalias. A tentative connection has been made between these glands and insects that would suggest a mutualistic relationship (as found in other Senegalia species). Ants are known to use the glands as a source of food and water, and may provide some defense for the plant against herbivorous insects. Like other arroyo trees in family Fabaceae, S. greggii is frequently afflicted with Desert Mistletoe, Phoradendron californicum. Unlike other legumes, S. greggii is not known to form root nodule associations with nitrogen-fixing bacteria. It is argued that this species may be an example of an evolutionary anachronism, in which the range and renewal of the species is limited due to the extinction of the mammalian megafauna responsible for seed dispersal. Within this model, the scarification required to germinate the seeds would have occurred during the chewing and digestion of the fruit by a large mammal, who later passes the seed intact some distance from the original tree. Gambel quail eat the seeds. Antelope browse the foliage, but more delicate species may do so cautiously on account of the thorns. ==Ethnobotany==

Senegalia greggii, even though it is used as forage for livestock, contains a potentially poisonous cyanogenic glycoside called prunasin. Mature seeds are to be avoided, as the native people did. The young, unripe beans of S. greggii were gathered and eaten by desert tribes of North America, including the Chemehuevi of the Southern Paiute, the Pima, and the Cahuilla. The Cahuilla also ground the dried beans for mush and cakes, while the Havasupai ground it to make flour for bread. The Seri ground the beans to meal then mixed it with water and sea lion oil for porridge. The Diegueno used S. greggii as food for domesticated animals. The Pimas and Tohono O'odham ate the seeds as pinole. ==Some chemical compounds found in Senegalia greggii==

• Beta-methylphenethylamine • Catechin • Fisetin • Hordenine • Phenethylamine • Quercetin • Tyramine ==Gallery==

Image:Acacia greggii branch.jpg| Image:Acacia greggii seeds.jpg| Image:Acacia greggii2.jpg| Image:Acacia-greggii-bark.jpg| ==References==