Physiognomy and Structure: No Data Available

Floristics: This alliance consists of intermittent to continuous cover of herbs <1 m in height. Amsinckia menziesii and/or Amsinckia tessellata is seasonally codominant in the herbaceous layer with Astragalus didymocarpus, Atriplex californica, Avena spp., Bromus diandrus, Bromus hordeaceus, Bromus rubens, Castilleja exserta, Dichelostemma capitatum, Erodium spp., Hemizonia fasciculata (= Deinandra fasciculata), Centromadia pungens, Hordeum murinum, Lasthenia californica, Lupinus bicolor, Phacelia spp., Plagiobothrys canescens, Plagiobothrys collinus, and Vulpia bromoides. Emergent shrubs may be present at low cover, including Adenostoma fasciculatum, Artemisia californica, Eastwoodia elegans, Encelia farinosa, Ericameria palmeri, Eriogonum fasciculatum, Isocoma menziesii, or Lupinus albifrons. In the Mojave, other herbs include Asclepias subulata, Chamaesyce polycarpa, Chorizanthe brevicornu, Erodium cicutarium, Eschscholzia minutiflora, Leptosiphon aureus, Lupinus sparsiflorus, Mirabilis laevis, Pectocarya recurvata, Phacelia distans, Physalis hederifolia, Plagiobothrys spp., Porophyllum gracile, Schismus spp., and Stillingia linearifolia. Associated emergent shrubs at open cover include Hymenoclea salsola, Acamptopappus sphaerocephalus, Ambrosia dumosa, Encelia farinosa, Eriogonum plumatella, Larrea tridentata, Salazaria mexicana, Stephanomeria pauciflora, Tetradymia stenolepis, Viguiera parishii, and Yucca schidigera.

Dynamics:  Some ecologists (Keeley 2006b, Wills 2006, Minnich 2008) have contended that upland areas in central and southern California had lower overall cover and lower grass than forb cover prior to European plant invasion, and fire was probably not important in such areas. Keeley also asserted that annual herbs tolerated a wide variety of fire regimes and that herbaceous landscapes burned at high frequencies close to Native American habitation, but they probably burned once or twice a century away from habitation sites because of infrequent lightning strikes. However, many native annual forbs, including Amsinckia spp., tend to respond favorably to fire, especially with the removal of thatch created by non-native annual grasses (Parsons and Stohlgren 1989, York 1997).

Researchers are unclear as to the proper management balance in emphasizing Amsinckia in stands while de-emphasizing non-natives. Schiffman (2007) suggested that Erodium spp. have very similar ecologies to the native annuals, and they regularly compete with Amsinckia and other native annuals, even under grazing. The non-native grasses, such as Bromus spp., attain stronger dominance during years with high precipitation (Bartolome et al. 2007). In central California, ecologists (Pavlik et al. 1993, Pavlik 1995, Carlsen et al. 1999, 2000) found that the presence of non-native annual grasses contributed to the decline of the rare Amsinckia grandiflora. They recommended long-term management by reducing non-native grass cover and by restoring and maintaining the native perennial bunchgrass stands of Poa secunda at intermediate densities to ensure the persistence of this rare species. Carlsen et al. (1999) also noted an inverse correlation between the native shrub Lupinus albifrons cover and the density of Amsinckia grandiflora over a 4-year period. Techniques used to enhance Amsinckia establishment include lowering the biomass of non-native species through burning, grazing, and fossorial mammal disturbance, along with planting Amsinckia and other native plants. As for grazing, seeds and herbage of all Amsinckia are toxic to livestock (especially cattle) because of high alkaloid and nitrate concentrations. This may be a reason why this native continues to persist throughout the California landscape.