Senegalia greggii

Senegalia greggii

Conservation status
Secure (NatureServe)
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fabales
Family:	Fabaceae
Genus:	Senegalia
Species:	S. greggii
Binomial name
*Senegalia greggii* (A.Gray) Britton & Rose
varieties
Senegalia greggii var. arizonica Isely Senegalia greggii var. greggii (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)

The specific epithet greggii refers to Josiah Gregg, author, explorer, and amateur naturalist of the American Southwest and northern Mexico.

Ecology

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.

Description

Senegalia greggii

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.

Ethnobotany

S. greggii, even though it is used as forage for livestock, contains a potentially poisonous cyanogenic glycoside called prunasin.^[1] 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, 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 Cahuilla and Pima used the fibers for sturdy construction material and firewood. The Havasupai split the twigs and used them for basketry, but also used the twigs as a broom to brush off metates. The Papago also used the broken twigs for baskets, and were curved to make intricate weaves in the baskets. The Pima used the dried bushes to pile them to make a brush fence. The branches were used to make cradle frames as well.

The Papago fitted the branches around the deer hunters' heads to make a disguise as a deer, and the buds and blossoms were dried to make perfume sachets by the women. The sticks were also used to dislodge saguaro fruits from the cactus body, and rods were curved to flesh animal skins. The Pima made bows out of the wood.^[2]