Calliandra eriophylla Benth. var. eriophylla

 By Amala Posey, Native Plants of Arizona , 2005
Common names: Fairyduster (1,3,4,7,8,9), Calliandra (1,5,8), False mesquite (1,7,8), Stickpea (1), Hairy-leaved calliandra (5), Pink mimosa (8), Pink-flowered acacia (8), Mesquitilla (5,9), Plumita (8), Gavia (8), Huajillo (3,4,7,8), Cabeza angel (3), Cabelleto de angel (3), Cabeze de angel (4), Cosahui (4).
Family: Fabaceae (1) (alt. Leguminosae) (3)
Synonymy: none
Etymology: The genus name, Calliandra , means “beautiful-stamens” with reference to their showy appearance. The species name, eriophylla is Greek for “wooly leaf” (2,8). In Spanish, Cabeza de angel refers to an angel's head or angel's hair (4).

 Identification:
Growth form: C. eriophylla is an low (7) intricately branched (6) spreading shrub that grows up to 1 meter high (3) and twice as wide with sparse semi-evergreen foliage (4) with unarmed light gray or whitish stems (3). Typically, it is low, almost creeping (3) or prostrate (8), toward its upper elevational limits, and erect and bushy at lower elevations (3). Spreading by means of underground stems (8).
Roots:
Stem: Slender (3), rigid and often divaricate (8), densely appressed-pubescent twigs and pubescent herbage (5) with unarmed light gray or whitish stems (3). Stipules subulate, 3-4 mm. long; petioles short, 1 cm long or less (6). Soft hairs appressed downward (7).
Leaves: The dark green leaves (5) are widely spaced and twice pinnately compound, with 2-4 pairs if pinnae, each with 7-9 (occasionally 10) pairs of leaflets 2-3 mm long (3). Leaves are generally cold deciduous, falling in winter and reappearing with or shortly before the flowers (3). Leaflets spread hispidulous with hairs 0.6-1 mm. long, glabrous above when young (6). Primary leaflets in usually three pairs (7).
Inflorescence/flowers: Showy flowers in dense, spherical heads 1 ¼ to 2 inches in diameter. Corollas are 5-6 mm long and inconspicuous. It is the pink, rose, or reddish purple filaments of the stamens, 5/8 to 1 inches long (7), that make the showy display (3). The filaments can also be white at the base and tipped with pink (5).
Fruit: Fruits are linear, velvety pods 5-7 mm wide and 3-7 cm long with thickened, cordlike margins (3,7) and a slender apical point 5-6 mm. long (7). Seeds lead gray, smooth, oblanceolate-obovate, 6-7 mm. long, 3 mm. broad (7). The pod splits and its halves stand widely apart for a long period (5).
Similar species: In Arizona and California , no other shrub has long, pink stamens. In the absence of flowers, the low stature and unarmed whitish or light gray stems help distinguish it from acacias and mimosas (3).

 Ecology
Life history: Woody shrub spreading by underground stems (3,6,7,8).
Native/introduced: Native (1).
Photosynthetic pathway:
Phenology: Flowers in February, March and April. Plants occasionally bloom again in September and October after good rains (3,9).
Distribution: C. eriophylla grows from southern Arizona and southeastern California south to central Mexico and northern Baja California (4) in the Lower Sonoran Zone (6) and desert grassland at 2,000 to 5,000 feet elevation (7). It is found in Arizona in the Mohave Desert and western Yavapai counties, in the Sonoran Desert and the desert grassland (8). It is found growing on limestone hills and dry gravelly soils (8) along washes in the drier parts of its range and on slopes and mesas elsewhere. In semi-desert grassland it is often a dominant woody plant on open slopes (3).

 Uses:
Calliandra eriopylla is grown as an ornamental and will survive temperatures as low as -12°C (3). It is now planted in xeriscaped median of city streets in the American Southwest (9). The plants are valuable browse for livestock and deer and, because of their rhizomatous habit, are important in erosion control (3). The shrubs may be closely cropped by livestock without injury because of the capacity of the plant to spread by means of underground sprouts (rhizomes) (7).

Notes:
Calliandra eriophylla has several pollinators, including bees, flies, butterflies (4) and hummingbirds (5). It is among the first perennials to bloom in Arizona Upland (4). The infrequent flower visitors include Apis mellifera, Xylocopa , dipterans, and lepidopterans. Plentiful nectar (2.17 mg total sugars/flower/24 hours) is produced, so it seems odd that the flowers are not more heavily used than they appear to be (3). Pollen is produced in packets that adhere to the wings of butterflies, which presumably transfer them from plant to plant. C. eriophylla also restores nitrogen to the soil through symbiotic actions of bacteria harbored in the root tissue (9). The seed is eaten by Bobwhite, Scaled, Gamble's, and Mearn's quail (8). During dry spells the leaves will wilt, but soon revive after rain(5).

References:

1. USDA, NRCS. 2005. The PLANTS Database, Version 3.5 ( http://plants.usda.gov ). Data compiled from various sources by Mark W. Skinner. National Plant Data Center , Baton Rouge , LA 70874-4490 USA .

2. Gledhill, D. 2002. The Names of Plants (3 rd ed). Cambridge University Press, Cambridge , United Kingdom .

3. Bowers, J.E., Burgess T.L., and Turner R.M. 1995. Sonoran Desert Plants, An Ecological Atlas. University of Arizona Press, Tucson , Arizona .

4. Phillips, S.J., and Comus, P, W. 2000. A Natural History of the Sonoran Desert . Arizona-Sonora Desert Museum Press, Tucson , Arizona .

5. Epple, A.O. 1995. A Field Guide to the Plants of Arizona . Globe Pequot Press, Guilford , Connecticut .

6. Shreve, F. and Wiggens, I.L. 1964. Vegetation and Flora of the Sonoran Desert , Volume 1. Stanford University Press, Stanford , California .

7. Benson, L. and Darrow, R.A. 1954. The Trees and Shrubs of the Southwestern Deserts. University of Arizona Press, Tucson , Arizona .

8. Vines, R. A. 1976. Trees, Shrubs and Woody Vines of the Southwest. University of Texas Press, Austin , Texas .