Plant of the Month (December) : Sourberry – Rhus trilobata/ Rhus aromatica

Sourberry (Rhus trilobata/Rhus aromatica) - Mother Nature's Backyard

 

Seeds are germinating, bulbs are emerging, but very few flowers can be found in early December.   So we were pleasantly surprised to see our Sourberry (Rhus trilobata/Rhus aromatica) coming into bloom, just in time to be our Plant of the Month.   The scientific name is pronounced roos  try-lo-BAY-tuh (roos  air-oh-MAT-ih-cuh).

Sourberry is known by a number of common names including Three-lobe sumac, Three-leaved sumac, Basket bush sumac, Oak-leaf sumac, Skunk bush and Lemita. It belongs to the same genus as our common Lemonadeberry (Rhus integrifolia) and Sugar bush (Rhus ovata).  It’s a ‘cousin’ to the local Laurel sumac (Malosma laurina) and Poison oak (Toxicodendron diversilobum).  All are members of the Sumac family (for more on the Anacardiaceae see: http://mother-natures-backyard.blogspot.com/2014/12/plant-of-month-december-lemonadeberry.html. 

 

Sourberry (Rhus trilobata/Rhus aromatica)

 

Like many other plants, the taxonomy of this species is currently being revised.  Previously, Rhus trilobata was considered a western N. American species; Rhus aromatica was viewed as a related eastern species.  It now appears that both may be the same species (Rhus aromatica), though much of the western literature – and the nursery trade – still refers to R. trilobata.  For clarity we’ll use both names, but focus on the natural history of this plant in the West (which is most relevant to California gardeners).

Rhus trilobata (aromatica) is native to western North America, from Alberta and Saskatchewan south to Texas and California – even into Mexico.  It grows in prairies and shrub lands, on a variety of sites including sandhills, seasonal stream beds, canyons and dry, rocky slopes.  In S. California, it can be found in the canyons and washes of interior valleys, in coastal sage scrub, chaparral and southern oak woodland, mostly below 3500 ft. elevation.   It grows in the Santa Monica Mountains and in the foothills of the San Gabriel Range.

Sourberry (Rhus trilobata/Rhus aromatica) - low-growing form

 

Sourberry is a winter-deciduous shrub that varies in growth habit across its Western range.  In some situations it’s a low (2-3 ft. tall) mounding groundcover (above).  In other places, it grows as a rounded, upright shrub which may reach heights of 6-8 ft. and similar spread (see photo below).  In moist conditions, plants spread by rhizomes, sometimes forming a thicket.  In drier S. California, plants will often remain as solitary shrubs for many years.   Plants have a lifespan of perhaps 30-40 years; they grow most rapidly during their first five years.

Sourberry (Rhus trilobata/Rhus aromatica) - taller form
 

Sourberry (Rhus trilobata/Rhus aromatica) - foliage

 

The foliage of Rhus trilobata (aromatica) is medium-green to blue-green most of the year, turning yellow to orange in fall - if temperatures are cold enough.  In the western L.A. Basin, fall leaf color is variable from year to year. Plants lose their leaves in fall (usually November in our area) and leaf out again in spring (often as early as February in milder climates).  The plants leaf out quickly, from pre-formed leaf buds.   Plants often don’t leaf out until after flowering.

Sourberry (Rhus trilobata/Rhus aromatica) - leaves, young bark

 

Sourberry leaves are three-lobed, glossy, leathery, 1 to 1 ½ inches across.  They look somewhat like those of Western poison oak (Toxicodendron diversilobum), though not as shiny and a smaller size. For good pictures comparing the two species see reference 1 (below).  

The young bark of Rhus trilobata (aromatica) is often a medium red-brown, but may be as light as a pale gray-brown, with pale hairs.  Older bark is gray-brown, mostly smooth and fissuring with age.  When branches are broken (or leaves are crushed), they release an aroma that is skunky-smelling to some (hence the common names ‘Skunk brush’ and ‘Stink-bush’).

The roots of Rhus trilobata (aromatica) are well-adapted for climates of the  American Southwest, including California.  Plants have both a deep taproot and a network of fibrous, shallower roots.  This combination allows them to make optimal use of intermittent rains, as well as tap into deep groundwater reserves during dry periods. Because of the deep taproot, plants resent being moved once established in the ground.

Sourberry (Rhus trilobata/Rhus aromatica) - flower
 buds, flowers

 

 

Sourberry (Rhus trilobata/Rhus aromatica) - close-up
 of flowers

 

Sourberry blooms in early spring (February-April) in much of S. California, though flowers may appear in winter at lower elevations.  Plants may be dioecious (separate male and female plants).  More commonly, plants contain both unisexual and bisexual flowers on the same plant.   Male and female flowers are both small (~ ¼ inch across), with yellow petals. Male flowers cluster along yellow catkins (like a willow) and are slightly paler in color, while female flowers occur in dense, brighter clusters at the ends of short branches. Flowers are primarily bee-pollinated.  We’ll try to update our close-up pictures of flowers – hopefully with pollinators - soon.

 

Sourberry (Rhus trilobata/Rhus aromatica) - green fruits

 

Sourberry (Rhus trilobata/Rhus aromatica) - ripe fruits

 

Those familiar with the fruits of Lemonadeberry and Sugar bush will immediately recognize similarities between the three species.  The fruits are small (about ¼ inch; 5-7 mm), sticky drupes that contain a single seed with a hard seed coat (a nutlet).  Fruits are initially green, becoming a dark red when ripe (see above).  Fruits ripen in late spring/early summer (June/July) at lower elevations in S. California; they may ripen as late as early fall in colder climates.  The fruits are loved by birds and animals – including humans!

Like Lemonadeberry, the fruits are covered with a sticky, sweet-sour secretion that tastes like lemon or lime.  In fact, the most common edible use for the fruits is to make ‘Rhus-ade’, a lemonade-like drink. Some Native Americans still grind dried Sourberry fruits and use them as flavoring for puddings, mush or bread.  In fact, the fruits can be used as a flavoring or seasoning in more ways than you might think.  For additional ideas for using the fruits see: http://mother-natures-backyard.blogspot.com/2015/05/california-gourmet-cooking-with.html  

 

Sourberry (Rhus trilobata/Rhus aromatica) - in garden.
 Mother Nature's Backyard

Sourberry is an undemanding plant.  It tolerates pH from 6.0 to at least 8.0, and grows fine in soils ranging from very sandy to clay.  If your soils drain very slowly, consider planting Rhus trilobata (aromatica) on a slope or atop a small berm (it’s intolerant of standing water).  While it can be found growing in full sun, it seems to do better in our area in part-shade.  If you have a hot, inland garden, plant it where it gets some afternoon shade.

Rhus trilobata (aromatica) is very drought tolerant.  However, it looks (and produces) best with occasional summer water.  Let the soils dry out between watering, then give the shrub a deep, slow soaking.  In many areas of the West, this plant experiences occasional summer rains. 

Sourberry (Rhus trilobata/Rhus aromatica) - young plant

 

Sourberry (Rhus trilobata/Rhus aromatica) - mature plant

While Rhus trilobata (aromatica) develops a nice natural shape over time, the best-shaped shrubs are given a yearly pruning to stimulate fullness.  Branches should be pruned back by ¼ to 1/3 of their length in fall (after leaves fall) or early winter.  This pruning simulates the animal browsing that shrubs experience in the wild.  Some individuals are mildly sensitive to chemicals produced by the foliage of plants in this genus.   We suggest wearing long sleeves and gloves when pruning (at least until you know you’re not affected).  Wash hands/arms after handling the foliage.

If you desire straight stems for basket-making or other crafts, you’ll need to cut some or all of the stems back to the ground in early winter (coppice).   While native traditions involve cutting or burning an entire stand every few years, we wonder if just cutting back 1/3 of the oldest stems might not work as well.  We’ll try this and report back.

Sourberry (Rhus trilobata/Rhus aromatica) - rest stop
 planting, Utah

 

Sourberry is often used as a large shrub, either shaped or natural, in garden plantings. It contributes to the woodsy, natural look that some gardeners prize.  It can also be used as a hedge plant, remembering that it is winter-deciduous.  It does well on slopes, often getting by with little supplemental summer water once established. It is widely used for erosion control on slopes and in riparian areas. And Rhus trilobata (aromatica) is becoming more common in commercial plantings, due to its drought tolerance and low maintenance.

Sourberry can be grown in a large container – even used as a bonsai plant.  The lower-growing forms are useful as a woody groundcover under trees.  The cultivars ‘Autumn Amber’ and ‘Gro-low’, which are available commercially, grows less than 2 ft. tall, and are popular as groundcovers.

Sourberry (Rhus trilobata/Rhus aromatica) - used as ground
cover. Rancho Santa Ana Botanic Garden, Claremont, CA.

 

Of the many shrubs planted in S. California gardens, Rhus trilobata (aromatica) has some distinct advantages.  First, it is a great habitat plant.  Its size, many small flowers, dense foliage and edible fruits make this a good choice for bird and insect habitat.  If you don’t use the fruits yourself, don’t worry; plenty of fruit-eating birds will be glad to remedy the situation.

If you are a basket-maker, planting Rhus trilobata (aromatica) insures a ready source of the straight stems needed for your craft. [2]  This has always been an important basketry plant, wherever it grows.  If you need it for your craft, grow it.

Sourberry, along with the other local Rhus species, is also a useful plant for the natural dyer.  Leaves, prunings, ashes and fruits can all be used to mordant yarn or fabric prior to dyeing.  The plants are high in tannins, and tan-brown dyes can be obtained from leaves, bark and roots; pink-tan dyes are possible from the fruits. 

 

Sourberry (Rhus trilobata/Rhus aromatica) - green foliage
provides nice contrast in the summer/fall garden

 

Another good reason to grow this plant is its medicinal properties.  As always, medicinal plants should be used with caution – particularly those from families with known toxicities, like the Sumacs. For more on precautions see: http://mother-natures-backyard.blogspot.com/2015/10/garden-of-health-making-tincture-for.html

Fruits of Rhus trilobata (aromatica) were traditionally sucked or chewed as a treatment for toothache, mouth sores or as a mouthwash.  Fruits ease the pain, in part due to their astringent chemicals.  A decoction of the fruits is also traditionally used for stomach problems, as well as a hair tonic.   

The leaves are astringent, diuretic, emetic and hemostatic; infusions made from leaves have several traditional uses, including to treat head colds and soothe skin itches. Dried, powdered leaves have been used to create soothing salves for mouth sores.  For more traditional uses of this plant see reference 3, below.

Sourberry (Rhus trilobata/Rhus aromatica)

 

In summary, Rhus trilobata (aromatica) is a shrub with much to recommend it.  We’re surprised is isn’t used more often in the garden setting.  So if you’ve got the space – even room for a large pot – you might want to consider this pretty and useful native.

 

For a gardening information sheet see: http://www.slideshare.net/cvadheim/gardening-sheet-rhus-trilobata 

 

For more pictures of this plant see: http://www.slideshare.net/cvadheim/rhus-trilobata-web-show

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

 

_____________________

1. http://nathistoc.bio.uci.edu/plants/Anacardiaceae/Rhus%20aromatica.htm
2. https://deborahsmall.wordpress.com/2009/01/31/joe-moreno-and-minnie-tafoya-gather-rhus-trilobata/
3. Native American Ethnobotany Database: http://naeb.brit.org/uses/search/     

 

 

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

 

 

 

Plant of the Month (November) : Clustered (California) Field Sedge – Carex praegracilis

Clustered field sedge (Carex praegracilis) - Mother Nature's Backyard

Few plants are blooming now in Mother Nature’s Backyard.  And those that are have already been featured as Plants of the Month.  But one of our favorite ground covers is perking up with the recent rains and cooler days.  So we’ve chosen Clustered field sedge (Carex praegracilis) as our Plant of the Month.  The species name is pronounced CARE-ex  pre-GRASS-ill-iss.

The sedges (genus Carex) are perennial, grass-like plants that grow in climates ranging from the tropics to the tundra; sub-Saharan Africa is the only continent with few species.    Most of the several thousand species grow in boggy, marshy places or near ponds and streams, but some are more drought tolerant. 

There are over one hundred and thirty Carex species native to California, the  vast majority growing solely or mostly in the Sierra Nevada Mountains or the mountains of N. California.  However, about 20-25 species are native to Los Angeles County or the S. Channel Islands. [2]   While most of them grow only in the San Gabriel Mountains, a few can be found in the lowlands as well.  Carex praegracilis is one of them.

 

Clustered field sedge (Carex praegracilis) - good example
 of California native sedge

 

The leaves of sedges are long, narrow and grass-like. In fact, many people mistake sedges for grasses. But sedges are actually close cousins, belonging to a different family entirely (the Cyperaceae) and having flowers quite different from those of the grasses. In fact, the flower stalks of the sedges are triangular in cross section.

The old saying 'sedges have edges, rushes are round, grasses have knees that bend to the ground' helps one remember a key difference between the grass-like plants.   Most sedges spread by rhizomes (underground stems), stolons (‘runners’) or roots, forming a lawn-like sod.  Sedges are used in some areas as a substitute for lawn grasses.

Clustered field sedge has a wide geographic range – from mid-western U.S. to the west coast.  In California, it grows in the California Floristic Province and desert mountain ranges, from sea level to about 7000 ft. (2500 m).  It once grew along the LA River, Ballona Creek and marshes, on Santa Catalina Island and in the Liebre, Tehachapi and San Gabriel Mountains. [3]  It likely was common, but unrecorded, in many other moist places in the lowlands of western Los Angeles County.  In S. California, it occurs in/near both freshwater and alkali wetlands, including those that are only seasonally wet.



Clustered field sedge (Carex praegracilis)

 

In the horticultural trade, Carex praegracilis is sometimes confused with (and sold as) Carex pansa, a shorter species native to several areas along California’s central and northern coast.  Both are similar in appearance and use in the garden.  But there are important differences between the two, including size: Carex pansa is only about 6-8 inches tall, while Carex praegracilis is slightly taller.  For a great discussion of the two species (and how to tell them apart) see reference 4, below.

 

Clustered field sedge (Carex praegracilis): fine-textured
 foliage

 

Clustered field sedge is a perennial with narrow, bright to medium green leaves typical of sedges. The leaves are slightly more narrow and longer than Carex pansa.   It grows about 1-2 ft. tall and looks superficially like a fine-bladed grass.  In fact, the species is commonly used as a grass substitute.  It spreads via stout, dark rhizomes (underground stems) to form a sod-like mat. 

 

 

Clustered field sedge (Carex praegracilis): spreads by
 rhizomes to create a sod-like mat

 

This species is a very useful addition to local gardens.  It tolerates full sun to part-shade.  We’ve found it looks best in part shade, and even have a nice stand growing north of a 10 ft. wall in Mother Nature’s Backyard (see below).  Carex praegracilis does fine in most local soils, from sandy to clay (we’ve grown it in both extremes).  It doesn’t mind the alkali soils found in some parts of our region.  

Clustered field sedge (Carex praegracilis): in shady
 position with Feltleaf everlasting

 

Clustered field sedge really needs no added fertilizer, though it probably wouldn’t harm it.  While young plants need regular water, established plants are quite drought tolerant. Carex praegracilis can get by with infrequent irrigation (deep watering several times a summer), though plants will go dormant.  To keep established plants green, water every 2-4 weeks, depending on soil type.  Taper off water in the fall, to give plants a bit of a rest.

Clustered field sedge (Carex praegracilis): naturally
 dormant under dry conditions

 

Like most Carex species, Carex praegracilis is best started as a purchased plant or as plugs.  In our experience, Clustered field sedge spreads more slowly than Carex pansa, taking several years to really establish in western Los Angeles County.  It may fill in more quickly in wetter regions (or with more irrigation than we give it).  If used as a lawn substitute, we suggest planting plugs 8-10 inches apart. 

Carex praegracilis is a cool season, sod-forming sedge, so it does most of its growth in winter and spring in lowland S. California.   It blooms in late spring or early summer.  The blooms, on stalks that are somewhat taller than the leaves, are pale green, fading to tan fruits with white tips. The flowers and fruits are not particularly noticeable, although characteristic of the species; we’ll get some photos next year.  For good photos see reference 5, below.

Clustered field sedge (Carex praegracilis): nice
natural groundcover

 

Clustered field sedge is worth considering when you want the appearance of ‘grass’ in an easy care, water-wise native.  It’s very low maintenance; all that’s needed is to cut back to remove the brown foliage (if any) in late fall.  If it spreads into areas where it’s not wanted, just pull out the young plantlets.

Clustered field sedge makes a good natural lawn substitute, and established plots can even be mowed (4-6 inches) several times during the growing season. Sedge lawns can be walked on, though probably not the best choice for heavy use.  The sod grasses are still the best option for playing fields and other heavy traffic areas.   But if you just need a water-wise, decorative green ‘lawn’, Carex praegracilis could be a good choice.

Clustered field sedge (Carex praegracilis): low maintenance

 

We like Clustered field sedge left un-mowed, allowing it to form a natural groundcover under and around trees/shrubs. It is a great natural groundcover for vegetated (infiltration) swales, and can be mixed with other groundcovers liking seasonal water.   It does well on slopes and can be very useful there.  If watered, it can be used as a fire-resistant buffer plant in fire-prone areas.   You can even grow it in a pot for spot of greenery on a shady porch.

Incredibly adaptable and drought-resistant, Carex praegracilis may be just the plant you need to create a ‘green oasis’ in your water-wise garden. It’s locally native, delicate of appearance, yet tough as nails.  It fills in between plants, providing needed contrast for other native plants.  We couldn’t garden without it!

Clustered field sedge (Carex praegracilis):  nice addition
 to many gardens

 

 

For a gardening information sheet see: http://www.slideshare.net/cvadheim/gardening-sheet-carex-praegracilis

For more pictures of this plant see: http://www.slideshare.net/cvadheim/carex-praegracilis-web-show

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

 

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1.            http://www.greenleeandassociates.com/carex-pansa.html

2.            http://www.calflora.org/cgi-bin/specieslist.cgi?row_to_start=150&num_matches=172&tmpfile=cf158936&format=photos&next=next+22 

3.            http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=17745           

4.            http://www.pacifichorticulture.org/articles/a-sedge-by-another-name/

5.            http://calphotos.berkeley.edu/cgi/img_query?where-genre=Plant&where-taxon=Carex+praegracilis

 

 

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

 

 

 

Winter Drought? You’ve Just Gotta Water

 

 Strong El Niño conditions in the Pacific.  Plenty of rain and snow in Northern California and the Sierras.   But here in Southern California – and particularly in western Los Angeles County – gardeners are wondering ‘where’s our El Niño?’  Instead of record rains, we seem to be entering our 5^th year of drought very early this year.  And a dry winter means you’ve just got to water your native plants.

Many Southern California native plants are really drought tolerant. You can read about why at: http://mother-natures-backyard.blogspot.com/2015/10/how-things-work-plant-drought-tolerance.html  But plants from western Los Angeles and Orange Counties need at least 10 inches of winter rain (or irrigation) to survive.  Winter rains are what make our local plants both water-wise and lovely.   The rains  allow them to cope with our long, hot, dry summer and fall.

Southern California homeowners are struggling to meet their targeted 25% reduction in water use this winter.  Local water companies recently bemoaned our 17% reduction compared to 2013.  Which leads us to wonder: ‘Have they looked out the window?’  It’s dry this winter; and most of us don’t want to lose the mature trees and shrubs that shade and cool our neighborhoods.  And so we water.

Plants from Mediterranean climates are the best-suited water-wise plants for our region. They should dominate our home and commercial landscapes.  Many are very water-wise in the summer/fall, when we most need to conserve water.  They can result in significant yearly water savings when used to replace summer-thirsty tropical plants and wet-climate grasses.   In fact, they are more water-wise than the semi-tropical succulents many people are now planting to conserve water.  So water agencies, state officials and teachers should be encouraging gardeners to plant water-wise Mediterranean climate plants, and most importantly, California natives.  

But local water companies don’t yet seem to understand that Mediterranean climate plants, including Mediterranean herbs and citrus trees, must be watered in dry winters.  And some dry winters are to be expected in in Southern California.  Ideally, water budgets should take year-to-year variability into account; computerized data allow water agencies to do so.  

A ‘one size fits all’ approach to water conservation doesn’t make sense in times of rapid climate change.  Our current water targets are based on 2013 monthly water use levels.   And the 2012/2013 season, while dry over-all, started with a fairly normal winter (in which little supplemental water was needed).   We were gardening along with the rest of you in 2013.  So we know: our soils were moist well into spring that year without supplemental water.

Some of us have been given ‘water budgets’ that specify the number of CCFs we can use each month (based on a 25% reduction from 2013 levels).  A CCF is hundred cubic feet of water (the first ‘C’ is the Roman numeral for 100); one CCF is equivalent to 748 gallons.  Five CCFs per month is about the lowest feasible level if you have any sort of a garden at all.  A small family can get down to 3-4 CCFs per month with vigilant indoor water saving and almost no outside water use.  But it’s not easy to keep a garden going on 5 CCFs per month during a significant winter drought.

Fortunately, some water companies allow customers to ‘bank’ CCFs not used.  If your garden features native/mediterranean plants, and if you follow our suggestions for surviving the drought (see http://mother-natures-backyard.blogspot.com/2015/07/surviving-drought.html), you can actually save excess CCFs for winter drought watering.  But even if you don’t have saved credits, you can keep your winter water use reasonable, while still maintaining healthy plants.  Here are a few suggestions:

1. Save as much water indoors as possible.  Many of us still take sponge baths most days, wear our outer clothes longer between washings and use rinse water to fill our toilet tanks and water our plants.  Water saved indoors can be used to water your garden plants.
2. Prioritize your watering. Don’t waste water on plants that need replacing.  Be sure that trees, large shrubs and other plants that provide shade, food or other important services get first priority.
3. Check the long-range weather forecast.  If no rain is predicted for the next 10 days – and if your soil is dry – you need to consider watering.
4. Check your soil moisture. Dig down to a depth of 3-4 inches.  If the soil is dry –and there’s no rain in sight - it’s time to water.  Don’t rely on plants to tell you when to water; you need to check the soil.  At this time of year, the soil should be moist; if not, you need to water.  There is no substitute for checking your soil moisture.
5. Check soil moisture in several places; water accordingly.  Shadier, sheltered parts of the garden remain moist longer than sunny areas.  Be sure to water only parts of the garden that really need it.
6. Water on days that are cool (or at least relatively so). We’ve had a spate of summery, hot weather this winter.  Check the weather forecast for days with on-shore breezes and a chance of fog; those are the days to water.  Watering on cooler days benefits the garden in at least two ways:
1. Water is more likely to percolate into the soil, rather than evaporate;
2. Water and warm temperatures encourage fungal and other plant pathogens.   By watering during a cool period you stand the best chance of avoiding disease problems associated with warm, moist conditions.
7. Water at cool times of the day.   We’ve done well with winter watering late in the day.  The water has time to percolate into the ground overnight.
8. Use watering methods that decrease evaporation.  Trickle-water with a hose, use soaker hoses or old-fashioned ‘whirligig’ sprinklers that produce larger drops.  Sprinklers that produce a lot of mist waste water.
9. Remember that large, water-wise plants have extensive root systems. Be sure to water out to the drip-line and beyond.  If you’re using drip irrigation to establish plants, move the emitters out as the plants grow.
10. Install permeable paving for patios, walkways, etc. These allow all the water that falls on your garden to percolate in.  For more on permeable paving options see: http://mother-natures-backyard.blogspot.com/2013/06/harvesting-rain-permeable-paths-patios.html

 

Have faith – we’ll get through the drought, although our gardens will likely evolve to accommodate our changing climate.   Look at the drought as a challenge and an opportunity; a chance to make your garden even more alive and interesting than it is today.  Consider ways to incorporate more native plants in your garden.   And for now, if your Mediterranean climate plants need water, you’ll just have to water. 

 

 

 

 

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