Hollyleaf Cherry

Prunus illicifolia

Prunus ilicifolia (with wide leaves) in October 2015 on 60% of ET0; overall form is mounding. Photo: SK Reid..

Summary

Uneven mortality before irrigation treatments began (50% mortality for the 40% ETo treatment; 33% for the 20% ETo treatment) confounded significant statistical analysis of the growth parameters for this California native species. Only the highest irrigation treatment had additional mortality during the treatment period. Additionally, although all plants came from one nursery, there were several plants with seemingly significant morphological differences (leaf size and shape; overall plant shape) leading us to believe they may have been a subspecies. For the purposes of this report, all plants were evaluated together, since we were unsure if that level of leaf variance was possible within the species if, for instance, they were grown from collected seed. From this data set, there did not appear to be any significant differences in relative growth between treatments, while the best overall appearance was found on 60% of ETo (Table 7). This may initially be surprising until one considers that the natural distribution of the plant is along the coastal chaparral and woodland areas. The CalFlora website (www.CalFlora.org) lists its suitable growing areas as those with July highs of 96ºF, while Central Valley high temperatures in July and August usually will reach 100ºF or more for several to many days. However, if one considers that the plants on the 60% treatment also happened to be the largest (and probably most robust) plants going into the treatment period, it is hard to draw any conclusions about size with respect to irrigation. The average foliage ratings were very good on all treatments, showing a strong resistance to disease and pest pressure, but the non-uniformity of the plants within treatments led to downgraded overall appearance on most irrigation levels. This level of irregularity would make it suitable only to very informal garden settings.

Growth and Quality Data

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Prunus ilicifolia (with smaller leaves) in September 2015 on 60% ET0; strikingly different overall form than wide-leaved specimens. Photo: SK Reid.