Acacia Greggii - Ecology

Ecology

A. 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. A. greggii has extrafloral nectaries, a trait shared with other acacias. A tentative connection has been made between these glands and insects that would suggest a mutualistic relationship (as found in other Acacia 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, A. greggii is frequently afflicted with Desert Mistletoe, Phoradendron californicum. Unlike other legumes, A. 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.