NEPHROLEPIS CORDIEOLIA (NEPHROLEPIDACEAE) NATURALIZED IN SOUTHERN CALIFORNIA (U.S.A.): WITH NOTES ON UNINTENDED CONSEQUENCES OF ESCAPED GARDEN PLANTS

摘要

Nephrolepis cordifolia occurs in many tropical, subtropical, mild-temperate, and Mediterranean regions of the world. Because it is widely cultivated, and there are many cultivars, populations have escaped from gardens and naturalized; these escapes have likely obscured its ancestral native distribution. Nephrolepis cordifolia is also frequently cultivated in southern California, especially for groundcover since it adapts well to a variety of soil types, tolerates full sun, and is drought-tolerant. Wereport here that Nephrolepis cordifolia grows outside of cultivation on concrete walls, trunks of palm trees, calcareous cliffs, and an ocean bluff in Los Angeles and Orange counties, coastal southern California. A naturalized population documented previously in 2006 from a streamside habitat in San Diego County was not relocated in 2014. Documentation of ornamental plants that have escaped cultivation, especially in urban habitats, is an important but often overlooked component of establishing time lag phases and early pathways of dispersal for potentially invasive plant species introduced to new regions. We provide notes on identification of N. cordifolia, its native and introduced ranges, garden plants and invasive weed introductions, and discussion of naturalized habitats in southern California. We also cite voucher specimens and photographic documentation of the occurrence of this species in southern California.