The Four Best Trees to Plant in or near Your Rain Garden

Rain gardens are attractive landscaping features that can not only improve the aesthetics of most properties, but they provide important environmental benefits too.

When properly designed, rain gardens capture and contain a relatively large quantity of rainwater, which will then percolate into the soil over the next few days. This helps to prevent some of the problems that excessive amounts of runoff water often cause. The water collected can also be used to support plants and trees – including species which may normally require more water than is typically available in the area.

Rain gardens can be designed in a variety of different ways, but most are essentially created by digging a small to medium depression and then installing a channel that supplies the garden with rainwater collected from a downspout or gutter. Plants are then installed in the depression, and various gravels and soil amendments are added to ensure a good percolation rate. Note that rain gardens are not ponds – there should be no standing water left in the depression a few days after the rain ends.

Most of the vegetation planted in rain gardens consists of shrubs and herbaceous plants, but you can also install trees in a rain garden if you wish. However, you must pick species that can adapt to the conditions present in or near the rain garden if you want to give the trees the best chance of thriving.

Note that rain gardens usually contain several different microhabitats, which will support different types of trees. The soil in the lowest part of the depression will stay relatively damp, making it perfect for trees that have high water requirements, while the elevated areas around the perimeter of the rain garden will feature drier soil, which is better suited for trees with modest water requirements.

There are a variety of different trees that can be used in rain gardens, but the following four are good candidates.

1. Bald Cypress (Taxodium distichum)

An iconic tree of southern swamps, the bald cypress is a natural choice for rain gardens. When provided with sufficient water, bald cypresses grow well in Southern California, and they’ll work well in the lowest portions of your rain garden. The biggest challenge bald cypresses present is their mature size, as these are large trees, which reach 60 to 80 feet in height.

2. Goodding’s Willow (Salix gooddingii)

Many different willow species are great choices for rain gardens, but Goodding’s willow is among the best species to use in Southern California. The Goodding’s willow is native to the state, and it provides food and shelter for a variety of bird species too. Although it isn’t a gigantic tree, the Goodding’s willow can reach about 25 to 30 feet in height, so it isn’t ideal for tiny rain gardens. Goodding’s willow will adapt to most parts of the rain garden, including the lowest levels of the depression.

3. Red Maple (Acer rubrum)

Like the bald cypress, the red maple is another denizen of damp eastern forests that also grows well in California. Red maples thrive in soils of varying moisture levels, so they can be installed in just about any portion of your rain garden. They will adapt to the relatively dry soils found at the upper levels or the damp low-lying sections in the middle of the depression. Red maples provide incredible color in the fall and – to a lesser extent – the spring. They do produce relatively invasive roots, so be sure to avoid planting them near sidewalks or other hardscapes.

4. Chinese Fringe Tree (Chionanthus retusus)

The Chinese fringe tree is a moisture-loving species that will work well in the middle portions of your rain garden. Famous for its showy, white flowers, the Chinese fringe tree is a small- to medium-sized tree, which typically reaches heights of 10 to 20 feet. The tree often attracts plenty of birds, bees and butterflies, which feed on the fruit and nectar produced by the tree. Note that this tree can cause allergy problems for some people, so it may not be a good choice for rain gardens that are located close to bedroom windows, backyard porches or front doors.

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If you are considering installing a rain garden on your property, or you would like to add a few trees near an existing rain garden, give your friends at Evergreen Arborist Consultants a call. One of our arborists will examine the area and recommend a few of the best species for the site. We can even help you with the installation process if you like.

Five Great Fruit Trees for Southern California Yards

Fruit trees are great additions to almost any yard, as they not only offer the same benefits most other trees do, they also provide you with a bounty of fruit each year. Several fruit trees also exhibit a very attractive growth habit, and a few produce beautiful, showy flowers in the spring or summer.

But to ensure your fruit tree installation is a success, you’ll need to select good species for your property. Fortunately, residents of Southern California have a number of viable options from which they can choose.

1. Persimmon

Persimmon trees (Diospyros spp.) are 20- to 40-foot-tall trees that are native to various portions of North America and Asia. They are handsome trees, with attractive bark that produce huge quantities of fleshy fruits. However, not all persimmons are created equally: Many, such as the American persimmon (Diospyros virginiana) contain bitter-tasting tannins. Accordingly, you’ll want to go with the Fuyu persimmon (Diospyros kaki‘Fuyu’), which produces very tasty fruits without many tannins at all.

2. Avocado

Avocados (Persea americana) have become very popular trees in southern California over the last decade or two, and it is easy to see why: They are very attractive, hardy trees with thick canopies, which means they not only provide delicious fruit, but privacy and shade too. You can grow avocados from seed, but you may have to wait a decade or more to get a good crop, so it is usually preferable to start with container-grown saplings. Note that different avocado varieties exhibit two different flowering patterns (termed A and B), and you’ll want some of each to achieve the best possible fruit set.

3.Meyer Lemon

The Meyer lemon tree (Citrus x meyeri) is a wonderful fruit tree for Southern California yards. Part lemon tree and part mandarin orange, Meyer lemons taste like low-acid lemons (which makes them great for deserts), and they can actually be eaten with the peel. Meyer lemons tend to exhibit a pretty bushy growth habit, and they produce sprawling root systems, so be sure that you have enough space to accommodate them before choosing them for your yard.

4. Fig Tree

Many fig trees will grow well in Southern California, but the Brown Turkey variety (Ficus carica ‘Brown Turkey’) is probably the one most ideally suited for our region. These 15- to 30-foot-tall trees grow best when planted somewhere with full sun exposure and deep, well-drained soil. Figs are deciduous trees, so they won’t provide shade in the summer. However, their growth form is quite attractive, and they still provide visual interest, even in the winter. Just be sure you like figs before planting a few of these trees, as they tend to produce two crops a year – one in late spring, and another in late summer.

5. Grapefruit

Another citrus tree that grows well in Southern California, grapefruit trees are especially well-suited for coastal areas, such as Malibu, Santa Monica and Long Beach. Several different varieties are suitable for our region, but the Marsh seedless (Citrus × paradisi ‘Marsh’) variety is one of the best choices. Grapefruit trees can be a bit tricky to grow, so you’ll need to plant them in an ideal spot to be successful – just be sure the trunk won’t be scorched in the sun, and that the soil is deep and loamy.

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If you’d like to add a few fruit trees to your yard, give your friends at Evergreen Arborist Consultants a call. We’ll assess your property, provide you with a few species recommendations and even install them for you, if you like. Proper species selection and installation is crucial for fruit tree health, so it always makes sense to solicit the help of professionals when you are starting out.

Bringing Fall Color to California: Enjoy the Changing of the Seasons

Most of the tree species that exhibit bold fall colors are native to the eastern portions of the US, with the best examples occurring in the northeast. In fact, people travel from miles around each year to check out the fall color in places like Vermont and New Hampshire.

Relatively few of the trees native to Southern California have jaw-dropping fall color, but that doesn’t mean you can’t enjoy watching the leaves change in the fall; you just need to plant a few of the right trees.

1. Maidenhair

If you like gold-colored leaves in the fall, there are few trees that can match the beauty of the maidenhair tree (Ginkgobiloba). One of the oldest tree species in the world, maidenhair trees are relicts from a time when dinosaurs walked the earth. Maidenhairs are big trees (some exceed 100 feet in height), so they aren’t appropriate for tiny lots. Be sure to select male cultivars when picking out your maidenhair trees, as the females produce copious quantities of foul-smelling seeds, which will stink up your entire yard.

2. Chinese pistache

The Chinese pistache (Pistacia chinensis) produces some of the best fall color of any tree that will grow well in Southern California. It is a moderately drought-tolerant, hardy species that is resistant to most local insects and diseases. Chinese pistaches reach about 50 feet in height, and they have a similar spread, thanks to their beautiful round canopies. Female pistache trees will produce small, purple to pink berries, which often attract birds and other wildlife. These trees will grow throughout most of our region, but because they tolerate pollution fairly well, they are one of the best choices for those living in the congested portions of Los Angeles and the surrounding area.

3. Sweetgums

If you just want eye-popping color, it is hard to go wrong with sweetgum trees (Liquidambar styraciflua). Sweetgums can produce gold, red and purple colors – sometimes in a single leaf. Sweetgums are big trees with incredibly invasive root systems, so you must be sure to select a planting location large enough to accommodate them. Naturally occurring sweetgum trees produce copious quantities of woody fruit, called gum balls, which can be quite a nuisance. Fortunately, many cultivars, such as the (Liquidambar styraciflua ‘Rotundiloba’), have been developed that do not produce fruit. However, the ‘Palo Alto’ cultivar produces better fall color and is ideally suited for the Southern California climate.

4.Japanese Maple

Maples are rightly celebrated for their impressive fall color, and the tiny Japanese maple (Acer palmatum) is no exception. Suitable for even the smallest properties, Japanese maples are famous for their slow growth rate and attractive branching structure. In our region, Japanese maples should usually be planted in partially shaded areas, so they won’t overheat in the California sunshine. Japanese maples aren’t very salt tolerant, so they are better choices for inland locations, such as Glendale and Pasadena.

5. Japanese Persimmon

The Japanese persimmon (Diospyros kaki) is a medium-sized tree that offers several different types of visual interest in the fall and winter. First, the green leaves will begin to turn yellow or orange. Shortly after this, they will begin to fall off, revealing the glorious orange fruit and the handsome, plate-like bark. Persimmons require well-drained, loamy soil, and they are moderately drought tolerant once established. In addition to the delicious fruit and attractive fall color they provide, persimmons also have very dense canopies that provide great shade.

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If you’d like some help adding a little fall color to your property, contact your friends at Evergreen Arborist Consultants. We’ll visit your property and help you figure out the best species to plant, and provide some tips for maximizing their color each year.

Picking Trees for Your Property: Going Beyond Hardiness Zones

It is always exciting to pick out new trees for your property, but there’s more to proper species selection than many people commonly suppose. For example, many homeowners and property managers rely solely on the USDA Hardiness Zone of their area to filter their possible choices. But while your local hardiness zone is an important factor to consider when deciding on the best trees for your property, there are plenty of other things you’ll want to factor into your selection algebra.

What Are USDA Hardiness Zones?

Hardiness zones are mapped out regions of the United States, which are created based on a single criterion: the annual low temperature. The zones are each designated by a number and a letter, with each number representing a 10-degree range, and each letter representing a 5-degree subdivision.

For example, places in USDA Hardiness Zone 9a experience winter lows of between 20 and 25 degrees Fahrenheit, while those in USDA Hardiness Zone 9b experience winter lows between 25 and 30 degrees Fahrenheit. Most portions of southern California are classified in USDA Hardiness Zones 8a through 10b (see full map of California’s hardiness zones here).

Yet while low winter temperatures are clearly an important consideration, they leave plenty of important information out. Sunset Zones are another useful classification scheme, whichare formed with more information than USDA Hardiness Zones are. Created by Sunset Magazine, Sunset Zones also consider things like humidity, length of the growing season and large-scale wind patterns to provide a clearer picture of your local growing conditions. Most regions of southern Californiaare classified in Sunset Zones 18 through 24.

However, they still fail to take into consideration plenty of other important criteria that will influence your new tree’s chances of survival.

Additional Considerations for Tree Selection

Don’t misunderstand: USDA Hardiness Zones and Sunset Zones are fantastic tools, which can help you rule out inappropriate species at the outset of your selection process. However, you’ll also want to consider the following criteria when selecting trees for your property.

Sun Exposure

California may be known as the Sunshine State, but that doesn’t necessarily mean your property enjoys full sun exposure. Your home, your neighbor’s trees and a number of other things can all created vast shaded areas. Some trees will thrive in these partially shaded areas, but you must be sure to choose those that can tolerate low light levels.

Space

Even native species, which are obviously well-suited for the southern California climate, may not thrive in your yard if you lack the space to properly host them. Accordingly, you’ll want to carefully assess the amount of space available, and choose a tree suitably sized for it. While you should definitely consider the height of any potential tree you select, it is more important to consider the tree’s spread.

Water Availability

Even if your geographic area receives ample rainfall, the local drainage patterns and hardscapes can alter the way water flows across the surface. This can leave some small areas within your property bereft of enough rain, while other areas may remain relatively damp all year long.

Potential Pests

A variety of native and invasive pests plague southern California, and you’ll need to avoid picking trees that are vulnerable to the local threats. Some invasive pests also exhibit very localized distributions, meaning that someone at one end of a zip code may plant vulnerable trees with impunity, while others must avoid doing so entirely.

Soil Characteristics

Even though the basic soil characteristics of a region change over the course of miles, small changes in chemistry, structure and composition often manifest over much smaller scales. This is because the large-scale soil characteristics are determined by the long-term geology and climate of the region, while the small-scale characteristics are chiefly the result of the ways humans have interacted with the land over the past few decades or centuries.

Wind

Sunset Zones consider large-scale wind patterns when devising their classifications, but they can’t possibly account for the fact that your yard is right next to a cliff, busy highway or open field – all of which can alter the local wind patterns. Most trees can adapt to relatively strong winds (particularly if these winds tend to blow in a single direction), but different trees withstand wind to different degrees, and you’ll need to consider the winds of your area before making your choice.

Environmental Health

Most trees will grow in pristine, virgin wilderness areas, but only a select few will thrive in polluted, urban areas. This isn’t as big of a consideration for those living in rural areas (although local farms can have a damaging effect on these areas), but those living in the city must consider the ability of any tree considered to withstand polluted air and water.

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Again, Sunset and Hardiness Zones can provide valuable information, and they should factor into your selection process. But it is important to look beyond these classifications, and weigh the tree’s needs against the specific characteristics of your yard.

If you’d like some help selecting the best trees for your property, contact your friends at Evergreen Arborist Consultants. Whether you live in Malibu, Beverly Hills, Pasadena or anywhere else in the greater Los Angeles Area, we’ll send out one of our certified arborists to analyze the local conditions and make recommendations for your new installation project.

 

 

The Magic of Mycorrhizae

Trees are amazing organisms that provide food, shelter and other resources for a variety of living things, including everything from mistletoe to humans. But while it is important to recognize the contributions trees provide to the rest of the planet, it is equally important to recognize the ways other species actually help trees to survive.

Many times, these relationships are symbiotic, or mutually beneficial. Some such relationships are obvious and visible — squirrels and jays, for example, help spread acorns throughout the landscape as part of their feeding and caching behaviors, which helps the trees colonize new areas and perpetuate the species. However, other symbiotic relationships occur out of plain sight.

Microorganisms in the Soil

Although soil appears to be little more than a mixture of dirt, rocks and bits of dead leaves, it is actually a thriving ecosystem, containing an unthinkable population of microorganisms. Some of these microorganisms are beneficial to trees, while others are harmful. Still others fail to interact with trees in any meaningful way.

One of the most important groups of microorganisms that interact with trees are beneficial fungi that live on and inside their roots. These fungi – called mycorrhizal fungi – play important roles in the biology of the trees. Mycorrhizae are fairly ubiquitous in healthy, undisturbed soils and they naturally colonize the roots growing in the area. However, urban soils, which often suffer from compaction are often deficient in these beneficial fungi, which can cause local trees to struggle.

The Mycorrhizal Connection

Mycorrhizal fungi and tree roots form a very tight-knit partnership. In fact, they are often referred to as a single entity: mycorrhizal roots, thanks to their strong bond and blurry boundaries. There are two basic ways in which the fungi interact with the roots: Many mycorrhizae coat the find absorbing roots of plants and trees, forming a type of living shield around the roots. However, some are actually able to penetrate the roots of trees, colonizing the spaces between the individual cells.

The Effects of Mycorrhizae

Mycorrhizal fungi help support tree health in a number of important ways. Some of the most important include:

  • Mycorrhizae help tree roots to absorb more water from the surrounding soil, via the increased surface area they provide to the roots. This not only makes the trees more efficient, it makes them better prepared to survive droughts and reduces their supplemental irrigation needs.
  • Mycorrhizae also helps to absorb more of the life-sustaining nutrients necessary from the soil. This means that trees with mycorrhizal roots require fewer fertilizers and soil amendments to remain healthy.
  • Mycorrhizae help protect tree roots from pathogens and harmful fungi. This is accomplished by helping to support the tree’s health (which naturally increases its ability to fight off pathogens), partially shielding the roots from contact with the pathogens, and by out-competing many of these harmful microorganisms for the resources they need.
  • Mycorrhizae help plants survive transplanting efforts, as they improve the tree’s ability to absorb water and nutrients from the new soil, which helps them to acclimate to their new location more quickly.

 

If you believe that your trees may be struggling in the often-sterile soils that characterize urban areas, give your favorite local arborists a call! We’d love to help analyze the soil situation of your property and make suggestions to improve it, so that your trees can reach their full potential.

Riparian Trees for California Properties

Riparian areas – the land adjacent to a river, creek or stream – are unique and important habitats. Because of their low elevation and proximity to waterways, they’re subject to frequent (and often extended) floods. Additionally, this proximity to water increases the number of insects and fungi living in these areas.

The species that dominate riparian areas – including everything from muskrats and water snakes to mosses and ironwoods – often exhibit adaptations that help them survive in these habitats. For example, the animals living in this zone are often skilled at collecting food from the nearby water in order to exploit the resource, while many of the plants have developed the ability to live in poorly drained soils.

Below, we’ll examine four of the best California natives for riparian areas. But, understand that these tree species will often work in other wet areas too. Try them in your raingarden or along the border of a farm pond. They will often thrive in these habitats as well.

California Sycamore

California sycamores (Platanus racemosa) are the titans of the riparian area – they not only reach large sizes (sometimes exceeding 80 feet in height), but they do so quickly, thanks to their growth rate, which can approach 3 feet per season. Sycamores frequently play the role of pioneer, given their rapid growth rate and appreciation of full sun exposure.

Sycamores have some of the most attractive trunks of California’s native trees. They are often light-tan to white in color, with multi-colored patches of brown, red or gray bark over the light-colored trunk wood.

Western Redbud

One of the best trees for California properties, western redbuds (Cercis occidentalis) are gorgeous trees that offer visual interest throughout most of the year. Their purple to pink flowers are some of the first to blossom in the early spring, and they are followed by charming, heart-shaped leaves in the summer, before shedding their leaves to show off their hanging seed pods, which will last well into the cool months.

Redbuds are often capable of surviving extended, even periodic, flooding. However, they often go semi-dormant and cease root production during inundated periods.

California Buckeye

Also known as the horse chestnut, the California buckeye (Aesculus californica) is an attractive, hardy tree that can survive in a number of different Californian ecosystems. Somewhat famous for their deadly fruit, horse chestnuts are actually toxic to a number of animals, including non-native bees and many other would-be pollinators.

California buckeyes have evolved an unusual timing to help thrive in California’s Mediterranean climate. For example, rather than leafing out in April or May, these 5-foot-tall trees often begin producing leaves in early February. Similarly, they may shed their leaves earlier in the summer than many others do – particularly if they are not provided with sufficient water.

California Bay Laurel

The California bay laurel (Umbellularia californica) is perhaps best known for its aromatic leaves, which smell like fresh pepper when crushed and have been used for centuries as a spice to flavor food. But that’s not the only thing these leaves are good for: People have long used them as a treatment for lice, fleas and other biting insects.

While bay laurels often grow in dense, shrub-like hedges, they also grow as proper trees, and occasionally reach 80 feet in height. This is most common in riparian areas or other places with adequate soil moisture, so be sure you understand the potential of these hardy trees before installing them on your property.

White Alders

Found throughout much of California and extending into Oregon, Washington and Idaho, the white alder (Alnus rhombifolia) is a common sight near low-lying, wet areas. A nitrogen-fixing species, white alders help to support the other plants living near them, by increasing the amount of nitrogen in the soil.

Alders are somewhat unique-looking in that their female catkins (flowers) often resemble miniature pine cones. The resulting seeds are spread via wind, seed-eating birds and water. This often results in the total colonization of riparian areas, creating a continuous canopy of these attractive trees.

 

If you’d like help selecting or installing trees for your streamside property or raingarden, give your friends at Evergreen Arborist Consultants a call. We can help you select and install the best trees for your property.

Poison Sumac

Poison Sumacs

Along with its relatives poison ivy (Toxicodendron radicans) and Pacific poison oak (Toxicodendron diversilobum), Poison sumac (Toxicodendronvernix) is one of the most notorious plants on Earth. Growing as a shrub or small tree, poison sumac can reach 20 feet in height, although they are usually somewhat smaller.

Poison sumac leaves are pinnately compound (feather-like) and arranged alternately on the branch. The leaflets have smooth margins and typically number 7 or 9, but occasional specimens may produce leaves with 11, 13 or 15 leaflets. The central stem of the leaflet – called the rachis – is red on young leaves and gray to brown on older leaves.

Toxicity

Like the other members of the genus Toxicodendron, poison sumac contains the potent allergen urushiol. Found throughout all of the plant’s tissues, the oil can cause a severe, itchy rash in humans who contact the plant. Rashes can result from contact with minute quantities of the oil, which can also be carried on clothing that has brushed against the plant. Even leaves that have been thoroughly dried remain potent.

Perhaps the greatest danger occurs when the plant is burned. This produces a thick, urushiol-laden smoke, which can wreak horrific damage on the lungs of any who breathe it. Many authorities claim that, by virtue of small differences in its chemical composition, urushiol from poison sumacs is more allergenic than that from poison ivy and poison oak.

Identifying Poison Sumac

Unlike poison ivy and poison oak, which are easy to identify by noting their “leaves of three,” poison sumac is a bit more difficult to identify in the landscape. You can look for the alternating, compound leaves bearing 7 to 9 leaflets. However, trouble ensues when people mistakenly observe the leaflets, which are arranged on opposite sides of the rachis, when they think they are observing the leaves – which are arranged alternately around the stem.

Accordingly, it is wise to consider other factors as well. For example, poison sumac tends to grow in very damp, acidic habitats (sometimes the roots actually grow into standing water). However, this is not a foolproof criterion – many ash trees (Fraxinus spp.) and true sumacs (Rhus spp.) grow in similar habitats and have compound leaves.

However, poison sumac produces round, waxy, white to yellow berries. By observing the combination of alternately arranged leaves and white berries, you can rule out most other species. Just remember the phrase: Berries of white make for a dangerous sight.

Wildlife Value

The berries of poison sumac trees typically persist well into the winter, hanging around long after the deciduous leaves have turned red and fallen to the forest floor. Accordingly, poison sumac is often an important food source for winter wildlife. Strangely, few animals (if any) appear to be allergic to urushiol.

Rabbits, squirrels, chipmunks, rats, mice and other small mammals are some of the most important consumers of the berries, and it is possible that many other mammals feed on them from time to time. Despite being most common in low-lying habitats, poison sumac berries appear to be relished by several upland game bird species, including bobwhites, pheasants and grouse.

Mombins

Mombins

Approximately 17 species comprise the genus Spondias.

Although they are most commonly called mombins, names like hog plum, gully plum, Spanish plum and golden apple are also applied to these trees. However, mombins are only distantly related to true apples and plums, so many of these alternative names are misleading.

These trees are primarily celebrated for the edible fruit that adorns most species in the genus, but some species are also used in ornamental plantings.

Growth Rate and Habit

Many mombins grow quite large, and, thanks to their rapid growth rates, they reach these impressive heights quickly. Some, such as the ambarella (Spondias dulcis) and the yellow mombins (Spondias mombins), grow up to 60 feet tall, while others, such as the jocote (Spondias purpurea) rarely exceed 20 feet in height. Other members of the genus, such as the imbu (Spondias tuberosa) remain relatively short, but produce 30-foot-wide canopies. Nevertheless, even the tallest members of the group typically remain somewhat small when planted outside of their natural range.

The wood of many mombins – particularly the fast growing species – is very light and buoyant. Several primitive cultures that live alongside mombins use the wood in the construction of canoes and rafts. Most species grow readily from seed, but some horticulturists grow them from cuttings.

Favored Fruit

Unsurprisingly given their close relationship, the fruit of mombins superficially resembles that of mango trees. Most species produce green-skinned, fleshy fruit containing a large, single seed, but the taste, texture and size of the fruit varies from one species to the next. Most mombins drop from the tree before ripening; over the following days and weeks, they become soft and more palatable.

While mombins are not yet a particularly popular food crop, officials are taking strides to increase mombin production in several rural, tropical locations. For example, Brazilian officials are hopeful that increased imbu production will provide both a food staple for locals and additional income through overseas sales.

While normally smaller than mangos, some mombins fruits reach very large sizes. Some mombins fruits reportedly grow to more than 1 pound in weight when grown in their native lands.

Ornamental Use

Several mombins make wonderful ornamental trees. The imbu, for example, is a very hardy, slow-growing tree that can thrive in most soil types and conditions. In addition to the species attractive, densely branched growth habit, they are also highly drought resistant, making them ideal for Californian yards and properties.

Ambarellas are more popular among those seeking quick-growing trees. Though a deciduous species, ambarellas remain handsome through the winter, courtesy of their impressive growth form. Ambarellas will grow almost anywhere mangos do, although they are not quite as cold hardy. Like the imbu, ambarellas require well-drained soils to thrive.

Most mombins produce small, inconspicuous, white to off-white flowers, which add little to the aesthetic value of the tree.

Toxins and Sap

Mombins are members of the family Anacardiaceae, making them close relatives of poison ivy (Toxicodendron radicans) and its notorious kin. Accordingly, some species, including yellow mombins, contain the toxic chemical urushiol in their sap. This can cause some who contact the plant to develop a severe rash.

Sumacs

Sumacs

Sumacs are a varied group of shrubs and small trees. Yet despite this diversity, most sumacs share a set of similar traits, including pinnately compound leaves, fruit comprised of clustered drupes and small adult size – the largest members of the group reach about 30 feet in height. Many sumacs play important roles in natural ecosystems, while others are popular ornamentals.

Several species have been used as a part of traditional folk medicine for hundreds of years. In fact, modern laboratory techniques have revealed that some sumacs boast antimicrobial properties.

A Fractured Family Tree

Sumacs are part of the cashew family (Anacardiaceae).

The cashew family is an enormous assemblage of plants, comprised of more than 700 different species, including the common mango (Mangiferaindica.), cashew trees (Anacardiumoccidentale), pistachios (Pistacia vera) and poison oak (Toxicodendrondiversilobum), to name a few. The size and complexity of the family have led to frequent changes in the classification of its constituent genera and species. Sumacs provide a great example.

The genus Rhus has contained more than 200 species for much of its history. However, modern botanists have begun reshaping the taxonomy of the group, and most of these species have been moved into other genera. As currently construed, Rhus contains a mere three dozen species.

You can learn more about the systematics of the entire Cashew family here.

Range

At its largest, the genus Rhus contained representatives from most corners of the globe. However, most of the species that remain in the genus are of North American, European or Asian origin. A few species are native to Australia. Africa was home to a number of Rhus species under the historic taxonomic arrangement; but most of these species have been moved, and are now part of the genus Searsia.

Sumacs grow in a wide variety of habitats and ecosystems. Most are early successional species, who quickly move into abandoned fields, vacant lots and fallow farmlands. This tendency – along with their propensity for sprouting additional stems from within existing root systems – often leads sumacs to become troublesome invasive species in some areas. However, in other areas, they are deliberately used in land reclamation projects, to revegetate stripped lands.

Notable Species

Skunkbush Sumac (Rhus trilobata) – Skunkbush, as it is most commonly called, lives throughout the western United States and Canada, including parts of California. Drawing its name from the objectionable odor released from crushed leaves, skunkbush often grows in dense thickets, as other sumacs do.

Fragrant Sumac (Rhus aromatica) – Fragrant sumac is a dense shrub, whose thrice-clustered leaflets superficially resemble those of poison ivy. Most individuals eventually grow to heights of 8 feet or more, but dwarf cultivars are available for smaller spaces. Fragrant sumacs are hardy, drought-resistant plants, capable of thriving on sun-bathed southern exposures.

Smooth Sumac (Rhus glabra) – Smooth sumacs are historically native to the eastern United States, but they have spread into a number of exotic locations, where their root suckering habits have caused them to spread invasively. While this leads many landowners to take steps to eradicate the plant, smooth sumac fruits are important foods for birds and other wildlife.

Staghorn Sumac (Rhus typhina) – Native to the northeastern United States and adjacent portions of Canada, staghorn sumac is widely planted as an ornamental. Several cultivars have been developed, such as the cut leaf form (Rhus typhina ‘Laciniata’). Staghorn sumacs reach about 15 feet in height, but their canopies may spread more than 20 feet. The berries of staghorn sumacs are used in making flavored drinks.

Prairie Flame Leaf Sumac (Rhus lanceolata) – Hailing from the south central United States and parts of Mexico, prairie flame leaf sumacs are also called Texas Sumacs. Like most other sumacs, they produce a short trunk with widely spreading branches. Texas sumacs are among the largest members of the genus, and occasionally reach 30 feet in height.

Poisonwood Trees

Poisonwood Trees

Poisonwood trees (Metopium spp.) are small to medium sized trees, native to Florida, Mexico, Central America and several Caribbean islands. As their common name indicates, they contain harmful chemicals, which limits their commercial value.

Basic Information

Poisonwood trees commonly reach about 20 to 40 feet in height, but some remain smaller and shrub-like. Most poisonwood tree trunks are short and bear several stout branches. The trunks vary from reddish-brown to gray, with numerous dark spots, produced by the tree’s copious amounts of thick sap.

The alternately arranged, evergreen leaves are pinnately compound (feather-like), and each bears three to seven leaflets. The trees’ evergreen nature contrasts sharply with that of its more temperate relatives, who lose their leaves each winter.

Itch-Inducing Trees

Members of the sumac family (Anacardiaceae), poisonwoods are close relatives of eastern poison ivy (Toxicodendron radicans), Pacific poison oak (Toxicodendron diversilobum) and poison sumac (Toxicodendronvernix). Like these notorious cousins, poisonwoods produce urushiol, the toxic component that causes an allergic reaction in many people. Accordingly, caution is warranted whenever working near these plants, and those living with the natural range of the plant are wise to learn to identify the species visually.

Urushiol is a highly potent irritant that can cause serious injuries. The substance is found in most parts of poisonwood trees, including the leaves, bark and inner wood. Despite containing this potent toxin, several native Central American cultures use the sap of poisonwood trees medicinally.

Classification and Species

As currently constructed, the genus Metopium contains three different species.

  • Black poisonwood (Metopium brownei)

  • Florida poisonwood (Metopium toxiferum)

  • Cuban poisonwood (Metopium venosum)

Given its wide distribution (including parts of the United States), Florida poisonwood is the best known member of the genus. Black and Cuban poisonwoods are relatively poorly known species, with restricted geographic distributions. Cuban poisonwoods, for example, are only found on the island of Cuba.

Commercial Use

While the black poisonwood is an important lumber species in many parts of Central America, neither of the other two species in the genus are commercially important. Black poisonwood is regarded as easy to work, hard, heavy and durable. It often features rich dark red colors and handsome figuring. It is primarily used to make interior goods, such as cabinets, furniture, and flooring; but it is also used in a variety of external applications, such as vehicle parts and bridge construction.

Ecology

Most species in the genus Metopium inhabit areas with very well-drained soil, such as pinelands, hardwood hammocks and sandy coastal dunes. Because they are typically tolerant of wildfires, which are common to many of the habitats in which they grow, poisonwoods often form pure stands, devoid of other species. Additionally, studies have found that these plants produce a variety of allelopathic chemicals, which inhibit the growth of nearby competitors.

Like their relatives, poisonwood trees rely on animals to disperse their seeds, which are tucked inside yellow drupes (berries). Many birds relish poisonwood tree fruits, including the endangered white-crowned pigeon, for whom it represents a vital resource. These birds spend their nights roosting in coastal mangrove forests, while their days are spent searching for poisonwood trees that grow farther inland.