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Tuesday, December 9, 2014

Plant of the Month (December) : Lemonadeberry (Lemonade sumac) – Rhus integrifolia

Three year old Lemonadeberry (Rhus integrifolia)
Mother Nature's Backyard garden

December is a quiet time in many Southern California gardens. This is just as well, given the flurry of other activities this time of year.  Plants are only beginning to respond to winter rains and the glory of fall is but a distant memory; it’s truly a quiet time.   However some plants do bloom in the cooler months from December through February.  For example, the native Lemonadeberry brightens a cloudy day with its masses of cheery pink flowers.

Lemonadeberry (Rhus integrifolia) is a member of the Anacardiaceae, the Sumac or Cashew family.  Other S. California natives in this family are the Poison oak (Toxicodendron diversilobum), the Laurel sumac (Malosma laurina) and the closely related Sugar bush (Rhus ovata) and Sourberry/Basket bush (Rhus trilobata).  The family includes a number of well-known members including the Cashew, Mango and Smoke Tree.  The non-native Brazilian and Peruvian Pepper trees, which have so naturalized that many think them S. California natives, are also members of this family.  

Trees and shrubs in the Anacardiaceae produce a milky sap which is poisonous – sometimes dangerously so. Fortunately, shrubs in the genus Rhus, the true Sumacs, are more of an irritant than a danger to most people.   This makes them good candidates for the home garden, where they can replace truly toxic non-native shrubs like the Oleander.   

The red-fruited true Sumacs (Rhus species) are now separated from their white-fruited cousins in the genus Toxicodendron (poison oak; poison ivy; poison sumac). Rhus species do not produce urushiol, the chemical responsible for the severe allergic reactions caused by poison oak and poison ivy.  While gardeners are advised to wear gloves and long sleeves when handling Lemonadeberry, the itchy rash associated with sap exposure is usually mild and short-lived.  Rhus fruits are used as spice or flavoring agent in both the Middle East and North America, where they grow native.

Rhus integrifolia, Palos Verdes peninsula, California (foreground)
Lemonadeberry is a true Southern California shrub, growing from south of Santa Barbara to Baja California, Mexico.   While primarily a coastal species, it ranges east to Riverside County, appearing in the Coastal Strand, Coastal Sage Scrub and Chaparral plant communities.   Typically it grows in drier canyons, either on north-facing slopes or slopes/bluffs facing the ocean.  A lowland species, Lemonadeberry is rarely found above about 2500 ft. (900 m.) elevation, its distribution likely limited by freezing temperatures.

Lemonadeberry is a large evergreen shrub, reaching a maximal height of 6-10 ft. in protected areas and 2-3 ft. along the immediate coast.  It is usually somewhat wider than tall, spreading to as much as 10-12 ft. in diameter in favored spots.  Interestingly, it can be kept to a much smaller size with regular pruning (more below).

Lemonadeberry (Rhus integrifolia): new foliage
Lemonadeberry (Rhus integrifolia): new foliage

The leaves of Rhus integrifolia are simple, usually light- to gray-green (although they may be darker) and rather thick, fleshy and waxy.  The leaves may have pinkish margins or midribs (the main vein of the leaf) and new leaves/branches are a shockingly bright pink or orange.   The bright color is due to the production of Anthocyanins – chemicals that provide a ‘natural sunscreen’ and herbivory deterrent to protect the delicate new growth.  The bright foliage adds a spot of color this time of year.  The older bark is gray and not particularly showy.
Students from CSU Dominguez Hills measure Lemonadeberry (Rhus integrifolia)
Palos Verdes peninsula, CA

Lemonadeberry shrubs are dense.  Their thick trunks are many-branched, starting quite low to the ground.  The new wood is soft – almost rubbery – but mature wood is dense and can be used for fuel.  The wood is pretty and distinctive in cross section, but we’re not aware its use in craft or furniture-making. In the wilds, young stems and branch tips are regularly nibbled by browsing animals, increasing the foliage density.  Mature plants in the wild are virtually impenetrable.

Flowering can occur at any time from December to February or March in S. California.  The timing reflects yearly climatic variability, primarily in temperature and precipitation (plants flower early in warm, dry years).  While small (1/4 inch), the flowers are showy, even in bud (see below).

Flowers & buds: Lemonadeberry (Rhus integrifolia)

Lemonadeberry flowers are simple affairs with five pink or sometimes white petals.  The flowers are clustered at the ends of branches, with literally thousands of flowers on a mature shrub.   The flowers, indeed the shrub itself, remind some of the non-native Indian Hawthorn (Rhaphiolepis indica), a common garden shrub in S. California.  In fact, Lemonadeberry is a good native substitute for Indian Hawthorn.

Close-up of Lemonadeberry flowers.  Left inset is male flower.

The flowers have a lightly sweet fragrance and are an importance source of nectar and pollen for winter-flying bees, their principal pollinators.  Individual plants may contain only male or only female flowers (dioecious), or a combination of bisexual (complete) and unisexual flowers (see above). This arrangement likely allows the species to maximize fertility in different environments.   The male and bisexual flowers have conspicuous anthers with yellow pollen (above).  Plants are not self-fertile, so you’ll need at least two for good fruit production. 

Fruits of Lemonadeberry (Rhus integrifolia).  Inset shows fully ripe fruits.
The fruits of Rhus integrifolia are drupes – small, flattened, fleshy fruits with a large seed or two.  The fruits start out a pink-white color and ripen to red-orange in late spring or summer.  Fruits are covered by a crystalline coating (see above) which has a distinctive tart flavor.  While native Californians sometimes eat the fruits fresh, many of us prefer to soak the pink fruits in warm or cool water to extract the lemony flavor.  The ‘flavored water’ that results (after the fruits are strained out) can be sweetened to produce a lemonade-like beverage. 

We assume that Lemonadeberry-flavored water can also be used to make a  distinctive jelly, dessert gelatin or syrup.  We’ll try these potential uses and report back; if all goes well, we’ll even feature the recipes in a future blog posting! (http://mother-natures-backyard.blogspot.com/2015/05/california-gourmet-cooking-with.html).   In the Middle East, red Rhus fruits are dried and ground into a spice that’s used on salads, meats or kebabs for a spicy lemon flavor.  We’ll also try this idea out when our fruits are ready.   

In our experience, the fruits don’t create any problems or mess.  If not used by humans, they will be gobbled up by Northern Mockingbirds, Jays, Flickers, Crows and other fruit-eating birds.  We rarely see fruits on the ground in our gardens.  However, we do see lots of birds eating, perching – even nesting – in our mature Lemonadeberry shrubs.

Lemonadeberry is very easy to grow in our area.  We’ve had good luck with it in compacted clay soils and sandy soils.  Needing little in the way of added soil nutrients or amendments, it can take alkali soils (pH 7.8 to at least 8.0 and likely higher).   It does fine in full sun, though it prefers a little afternoon shade in very hot inland gardens.  Its foliage is susceptible to frost damage; however plants will usually re-sprout unless low temperatures are severe or prolonged.

Lemonadeberry (Rhus integrifolia) in a garden.
Garden of Dreams, CSU Dominguez Hills.

Lemonadeberry is quite drought tolerant once established (2-3 years).  During the past two dry years we’ve summer-watered some plants every month, while others have received no supplemental water. Both groups have done just fine.   In Mother Nature’s Backyard, our Lemonadeberry was mulched with chipped wood at planting time.  We let mature plants self-mulch, supplemented with chopped up trimmings from the plants.

Lemonadeberry is a usefully substitute for non-native evergreen shrubs commonly used in local gardens.   Its size and density make it a useful background plant.  It  can also be trimmed for a water-wise foundation plant.   One of our favorite uses is as a hedge, screen or hedgerow shrub.  The dense foliage makes it an ideal ‘backbone plant’ for a mixed hedgerow; we like it combined with Toyon, Catalina and Hollyleaf cherries, and local Ceanothus species.   It is a great choice for slopes, where its deep fibrous roots bind the soil, limiting erosion.
Native plant hedgerow at CSU Dominguez Hills (Heritage Creek Preserve)
Lemonadeberry (Rhus integrifolia) is main shrub.

If growing Rhus integrifolia as a hedge or large shrub, realize that some plants are slow to get started and many experience a gangly adolescent phase.   As seen above, shrubs planted as one-gallon shoots grow to substantial size in six years, even in drought conditions.  But plants take time to grow and develop their mature shape.   We suggest letting Lemonadeberry grow naturally (without much pruning) for the first 2-3 years.     Once a plant begins to develop long side branches then it’s time to begin pruning. 

Even if you want a more natural shape, you’ll want to do some yearly pruning, at least in the beginning.  In the wilds, young plants are regularly ‘pruned’ by rabbits, deer and other animals.  That’s why wild plants often have a nice rounded shape!   In your garden, you’ll have to ‘be the deer’, cutting back unruly branches in late spring/summer.   In fact, you can prune anytime the plant is actively growing.  But you’ll sacrifice some flowers and fruits if you prune in fall.
How much pruning is needed?   That’s entirely up to you.  Some gardeners prefer a natural look – they prune only for safety or plant health.  At the other extreme, we’ve seen plants formally hedged to four feet tall.  A formal hedge will need regular (even monthly) hedge pruning to keep it neat and tidy.  The formally hedged plant will have fewer flowers and fruits; but no one will guess it’s a native plant and it will be very water-efficient!

Mixed hedgerow with Lemonadeberry, Toyon and native cherries.
Heritage Creek Preserve, CSU Dominguez Hills.

You can actually have the best of both worlds.  If a formally clipped hedge is needed (to face the neighbors), prune one side formally and the other (facing your garden) semi-formally.  This will often please all parties.  You needn’t be too worried about how to prune a Lemonadeberry – it’s a very forgiving plant.

We hope you’ll want to consider Lemonadeberry for your garden.  In addition to being pretty and evergreen, its adaptive ways and useful attributes make it a garden winner.  We already pointed out its culinary and habitat values.  In addition,  Rhus integrifolia leaves and smaller branches (e.g., prunings) can be used to dye natural cloth or yarn a nice tan color; they can also be used as a mordant to help bind other natural dyes.

Native Californians have several additional uses for Lemonadeberry.  Tea from the leaves is used in treating coughs and a drink made from ground seeds for fever.  The ground seed is also used with the fruits for tea; tea from the bark was used after childbirth.  The wood has been used as fuel.   And the seeds produce an oil which can be extracted and used for making candles. 

For plant information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html

Large lemonadeberry (Rhus integrifolia).
Rancho Santa Ana Botanic Garden, Claremont CA

Lemonadeberry in MNBY - 2016 (four years old)


We welcome your comments (below).  You can also send your questions to: mothernaturesbackyard10@gmail.com


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