About Mimosa aculeaticarpa Ortega
Catclaw mimosa, scientifically named Mimosa aculeaticarpa Ortega, is a straggling, thicket-forming shrub. It usually reaches around one metre in height, and occasionally grows twice as tall. Its twigs are hairy and equipped with backward-pointing spines that easily catch on clothing. Its alternate leaves are bi-pinnate, with a variable number of small oblong leaflets. The flowers are white or pale pink, clustered together in globular heads. The fruits are flat pods up to four centimetres long, flattened between the seeds, and split open when ripe. Recurved prickles grow along the edges of these pods.
This species grows in upland regions of central and southern Arizona, southern New Mexico, western and central Texas, and northern Mexico. It occurs as scattered individual plants in oak woodlands, oak-pine woodlands, evergreen woodlands, and pinyon-juniper woodland. It also grows mixed with other shrubs in grassland and shrub-steppe communities, and can be found on mesas, rocky slopes and gravel deposits. It is commonly found in chaparral, and is spreading into desert and semi-arid areas. This spread may occur because cattle eat the seed pods and deposit the seeds in dung, which provides a rich environment for seed germination. The plant is fire tolerant, and sprouts readily after bushfires. In upland areas of west Texas, redberry juniper (Juniperus pinchotii) acts as a nurse plant for catclaw mimosa seedlings. The seedlings benefit from the shade and leaf litter provided by the juniper, which creates a favourable microclimate for seedling establishment.
