(A.Gray) Britton & Rose
|Global occurrence of S. greggii|
|S. greggii var. greggii natural range|
|S. greggii var. wrightii natural range|
Senegalia greggii is a species of Senegalia native to the southwestern United States and northern Mexico, from the extreme south of Utah (where, at 37°10' N it is the northernmost naturally occurring Senegalia species anywhere in the world) south through southern Nevada, southeast California, Arizona, New Mexico and western Texas to Baja California, Sinaloa and Nuevo León in Mexico.
Common names include Catclaw Acacia, Catclaw Mesquite, Gregg's Catclaw, Devil's Claw, Paradise Flower, Wait-a-minute Tree, 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, that 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. (Note: "Cat's Claw" is also used to refer to Uncaria tomentosa, a woody vine found in the tropical jungles of South and Central America)
S. 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.
Devil's Claw 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 mammallian 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.
It is a large shrub or small tree growing to 10 m (33 ft) tall with a trunk up to 20–30 cm (7.9–11.8 in) diameter. The grey-green leaves are deciduous, and bipinnate, divided into 1-3 pairs of pinnae, each pinna 2–3 cm (0.79–1.18 in) long with 10-18 leaflets that are 3–6 mm (0.12–0.24 in). 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 flowers are produced in dense cylindrical spikes, each flower with five yellow 3 mm (0.12 in) petals and numerous yellow 6 mm (0.24 in) stamens. The fruit is a flat, twisted legume (pod) 6–15 cm (2.4–5.9 in) long, containing several hard, dark brown seeds. The seed pod is constricted between seeds (a loment), and seed dispersal occurs both through dehiscence and breaks at these constrictions.
S. 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. S. greggii young, unripe beans were gathered and eaten by desert tribes of North America, including the Chemehuevi of the Southern Paiute. Stems were used in construction and tool making.
Some chemical compounds found in Senegalia greggii
- Barlow, C. (2000). The Ghosts of Evolution: Nonsensical fruit, missing partners and other ecological anachronisms. Basic Books:NY.
- Jepson Manual Treatment: Senegalia greggii (as Acacia greggii)
- U.S. Forest Service FEIS Database: Senegalia greggii (as Acacia greggii)
- Lawor, Elizabeth Jane (1995). Archaeological Site-formation Processes Affecting Plant Remains in the Mojave Desert.. University of California, Riverside.
- Range Shrubs
- Interactive Distribution Map of Senegalia greggii (as Acacia greggii)
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