• Floral Biology of Jojoba (Simmondsia chinensis), an Anemophilous Plant

      Buchmann, Stephen L.; USDA Agricultural Research Service; Department of Ecology and Evolutionary Biology, University of Arizona (University of Arizona (Tucson, AZ), 1987)
      Simmondsia chinensis is a widespread perennial plant native to the Sonoran Desert of the United States and northern Mexico. Individuals are dioecious with small unisexual flowers borne on separate plants. The plants are strictly wind-pollinated (anemophilous). Honey bees (Apis mellifera) and native bees often collect large amounts of pollen from male plants but are never found visiting female plants, as there are no floral attractants or rewards in the form of volatiles or nectar, in the green apetalous female flowers. Male plants produce copious amounts of pollen, up to an estimated 523 g/plant, [0.5-2.4 mg/flower, or 8.3-48.9 mg/inflorescence]. Per anther there are from 11,000 to 18,000 pollen grains. The pollen is small, smooth with little exine sculpturing and averages 34μ in equatorial diameter. There is almost no surface oily pollenkitt on the grains. Anthers dehisce and pollen is shed during the entire day, but with an early afternoon peak from 1300 to 1500 MST. This corresponds to peak atmospheric concentrations of 60-63 grains/cubic meter during this period. Seasonal data for Jojoba aerial pollen concentrations and selected hourly values for certain days are also presented for 1982 and 1983 in a native stand. Data on floral number, floral ontogeny, stigmatic receptivity, and seeds per fruit, are also presented for Jojoba.