Updated: Nov 22, 2021
Need a lawn alternative that is drought tolerant? Myoporum parvifolium might be the plant for your design, but it includes some caveats. Unlike lawn, turf or sod (call it what you like), M. parvifolium is not intended to be walked upon. This is a visual alternative, a means of covering a lot of area in lush green using less water. If you have seen landscapes with ground cover junipers, they are a more appropriate comparison. Myoproum, which technically has no common name (regional common names exist, such as creeping boobialla), will produce these beautiful but small flowers, lending itself to a more pleasing, seasonal aesthetic. Their growth habit is to send out long limbs along the ground, continuously branching, and if conditions are right, send down roots along the way.
Other than being intolerant of being trodden upon, another concern is thrips, an insect so small that by the time damage is seen the infestation might be too late to successfully address. Thrips are smart; they distort the leaves and wrap themselves within making contact with topical insecticides nearly impossible. The link above to University of California's Integrated Pest Management Program (UC-IPM) discusses more effective remedies with systemic pesticides that the plants will absorb. How effective this program is will rely on multiple variables, but it may be worth it if there is a sea of Myoporum at risk.
Here's the thing, Myoporum, both as this ground cover shrub and its sibling tree form, Myoporum laetum, have been overly relied upon in California's ornamental landscapes. So much so that the latter has been designated as an invasive species, despite coastal cities still using them as street trees. This overabundance may have contributed to thrips being able to take over. Interestingly, while thrips love the tree form, for our subject ground cover, UC-IPM mentions thrips as unobserved to attack this species, meaning there is no official evidence that M. parvifolium would be attacked by thrips. Unfortunately for San Jose, we have had loss to thrips situations where M. parvifolium has been used in large masses, so we do not recommend its use any longer. This does not mean, however, that smaller quantities should not be specified...just adding here a reminder that monocultures can have high susceptibilities. Sunset notes that drought stress could also contribute to vulnerability from infestations (p. 448).
Each plant can spread up to 15' while maintaining a height no more than 18". Combined with its drought tolerance, it is easy to understand the appeal as a cover for bare soil. Given its potential vulnerability to thrips, however, plantings may be most useful for smaller infill situations over large mass plantings.
To diversify, here are some interesting cultivars, as examples:
'Pink': green leaves and pink blooms
'Fine Leaf Form' and/or 'Tucson': smaller leaves and plant size, more compact
'Davis': lighter green foliage with fragrant white flowers
'Red Leaf Form' and/or 'Burgundy Carpet': Tinged red foliage and stems
'Putah Creek': slightly larger leaves and overall height
Bay Area landscape architect Jeff Wortham provides unique observations for designers that should be considered if specifying on projects.
Botanical Name: Myoporum parvifolium
Myoporum: Greek, myein for to close; poros for pores (as is the case for many drought tolerant species, leaf pores, or stomata, close to minimize water loss
Parvifolium: Having small leaves
Common Name: No common name
Family Name: Scrophulariaceae
Positioning: Foreground, ground plane, hillsides, retaining walls/raised planters
Garden Themes: Coastal, Mediterranean/Australian/dry
Uses: Restoration, slope/erosion stabilization/streambed embankments, shade, reforestation, mass
Type: Evergreen shrub
Size: 18" tall by up to 15' wide
Outstanding Feature(s): Form, flower
Color: Dark green, may turn red-purple in winter
Surface: Glabrous and tuberculate
Flower: Spring to summer. Small, slightly tomentose, 5-petaled flowers with prominent white stamens. Axillary flowers may be white, pink, or white spotted pink. Can be showy.
Fruit: Summer to fall. Globular, yellow-green turning purple.
cultural requirements, tolerances & problems
Sunset Zones: 8-24
USDA Zones: 9-11
Light: Sun to partial shade
WUCOLS SF Bay Area Hydro Zone: Low
Texture: Sand, loam, clay
Moisture Retention: Well-drained
Tolerances: Coastal conditions
Branch Strength: Weak
Insects: Spider mites, thrips
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
CAL-IPC. "Myoporum laetum." California Invasive Plant Council, Berkeley. Accessed on September 3, 2021 from https://www.cal-ipc.org/plants/profile/myoporum-laetum-profile/.
eFlora of SA. "Myoporum parvifolium." Government of South Australia, Department of Environment and Water, Adelaide. Accessed on September 3, 2021, from http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&name=Myoporum_parvifolium.
Martin, C.A. "Virtual Library of Phoenix Landscape Plants." University of Arizona, Phoenix. Accessed on September 3, 2021, from http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/myoporumparvifolium.html.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
UC-IPM. "Myoporum Thrips." University of California Agriculture and Natural Resources, Davis. Accessed on September 3, 2021, from http://ipm.ucanr.edu/IPMPROJECT/contact.html.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on July 27, 2021.
Flower cluster: "Myoporum parvifolium (Creeping Boobialla; Creeping Myoporum)" by Arthur Chapman is licensed under flickr.
Ground cover mass: "210205 050 San Diego Botanic Gdn - Australian Gdn, Myoporum parvifolium Creeping Myoporum, Westringia fruticosa Coast Rosemary" by cultivar 413 is licensed under flickr.